EARTH SCIENCES LIBRARY MAI\UA: OF GEOLOGY: DESIGNED FOR THE USE OF S, COLLEGES AND ACADEMIES BY EBENEZER EMMONS, > STATE GEOLOGIST OF NOKTH CAROLINA, LATE STATE GEOLOGIST OF NEW YORK, PROFESSOR OF NATURAL HISTORY AND GEOLOGY IN WILLIAMS COLLEGE, ETC., ETC. |llsfrateb fcrifjj numerous SECOND EDITION NEW YOEK: PUBLISHED BY A. S. BARNES & BURR, 51 & 53 JOHN-STREET, AND SOLD BY BOOKSELLERS GENERALLY. 1860. VI PREFACE. ment of rocks on this side of the Atlantic agree with those upon the other. But inasmuch as we now have an American geology, let it be taught. It is for our interest to make foreign geology subservient to American. But we need not dwell on this subject. One of the most important studies for the young is classi- fication. Its advantages are not confined to natural history. In every sphere of knowledge it aids the mind to define and limit the boundaries of subjects, and perceive the true and constant relations they hold to each other. Our opinion of its utility led us to furnish an introduction to the subject, which, though imperfect, may still, as we believe, serve as a basis upon which classification may be taught. The plan we have followed in the preparation of the work differs somewhat from others. We have given in each chapter treating upon the systems of rocks, a general history of the period to which they belong. To this we have added a brief description of the rocks and their order of sequence. Each system is illustrated by the organisms or fossils which it is known to contain, and which have been generally selected from those which are the most common. The geo- graphical distribution of American formations completes the history of the several systems. Our illustrations of characteristic fossils may be regarded by some persons as out of proportion to the statement of facts and principles ; but it should be recollected that Palce- ontology has become the leading branch ; and from which we derive the most important information respecting the natural history of the earth. This feature of the work gives the general reader, as well as the student, an opportunity to form a correct idea of the progress of life upon the globe ; and will enable him to con- trast the palaeozoic with the cainozoic age, from which he will perceive the high standing of the organisms of the latter, when compared with the former. Geology is comparatively a modern science, and it cannot PREFACE. Vll be supposed that its doctrines will not require modification from time to time. Of this we are able to recall many in- stances. But with this admission we feel that it has already established a body of well settled principles, deduced from well determined facts and observations. These principles constitute a sure foundation, upon which is being reared a noble superstructure. Its progress has been in no respect different from other sciences. Chemistry had its alchemistic age, and geology its cosmogonists, but this fact does not diminish its importance, nor should it cast doubts upon its conclusions. < We are confident we are safe in the foregoing opinions, notwithstanding there remains a slight leaven of the old cos- mogonists. The fact is, some geologists belong naturally to this order of men, and geology proper would be too tame and spiritless, if it were not that some of the crust move- ments permit them to be converted in imagination into over- whelming convulsions. In treating those subjects which required a place in this work we did not deem it necessary to discuss them to ex- haustion. Much may have been said, which has been omitted. It is frequently enough to bring the subject up, and leave the discussion of it to the teacher. It is probable that our own views upon certain geological points may differ from those entertained by distinguished men. Where the discrepancies of views are worthy of note, they have been stated and maintained in this work ; because we have reason to believe that our opportunities for forming a correct one have been better than those from whom we differ, or because we have taken special pains to be rightly informed upon the subject, and hence have a legitimate right to an opinion. The present advanced state of geology demands a certain amount of information in the collateral sciences, chemistry, botany, and mineralogy. In the order of study the col- laterals stand first. To become an accomplished geologist Vlll PREFACE. requires a considerable amount of field information derived directly from observation. Collections should always be made and notes taken upon the spot, detailing all the im- portant phenomena a locality may furnish. It is the only mode by which remunerating results can be obtained. KALBIQH, May 1, 1859. TABLE OF CONTENTS. CHAPTER I. PAGE Knowledge and its departments Characteristics of man and the progress of kingdoms 13 CHAPTER II. Classification 17 CHAPTER III. Classification continued Vegetable and mineral kingdoms ... 37 CHAPTER IV. Geology defined Its objects, advantages Means by which it is acquired, and the rules by which its phenomena are interpreted Sources of information pointed out Importance of the testimony of organic re- mains Geology based on authentic records The three periods Origin of water, and continental rivers and seas 42 CHAPTER V. Of geologic forces Fire and water considered as agents of change Dynamics and statics of geology 46 CHAPTER VI. Classification and nomenclature of rocks ...... 51 CHAPTER VII. Classification of the Pyro-crystalline Rocks Age of Granite and its asso- ciates Successive formation of Granite and its distribution Individual rocks described, Ac 57 CHAPTER VIII. Second System, the Laminated Pyro-crystalline Rocks, Gneiss, and allied . compounds Third System, the Pyro-plastic Rocks, Basalt, Greenstone, Traps, Porphyries, &c. . . . 64 CHAPTER IX. The Pyro-plastio Rocks 68 (9) X CONTENTS. CHAPTER X. PAGE Of the Sediments or Hydro-plastic Rocks Agents concerned in their pro- duction Recognisable base Progress of life during the sedimentary periods Amount of sediments Geologic time ..... 71 CHAPTER XL Taconic System Divided into Upper and Lower Fossils of both divi- sions . ........... 81 CHAPTER XII. Silurian System General statement of facts relative to its epoch De- scription and division of the members composing the system, its fossils, Ac ^. 90 CHAPTER XIII. Devonian System 125 CHAPTER XIV. Carboniferous System An important epoch A stand-point for reckoning geologic time, vegetation, coal, and prospective material designed for the use of man Formation illustrated Vegetable fossils Division of the system into Lower Carboniferous, and the Coal Measures, &c. Reca- pitulation 153 CHAPTER XV. Permian System Phenomena marking the close of the Palaeozoic Divi- sion Author of the system, and derivation of its name Changes in the organic remains Permian of the Atlantic slope Development in North Carolina System described under the name Chatham Series, fossils, Ac 172 CHAPTER XVI. Triassic System Divided into three members Base of the Mesozoic Divi- sion Mineral contents Its fauna and flora Imprints of the feet of birds and batrachians 185 CHAPTER XVII. Jurassic System Imperfectly represented in this country Its position on the continent of Europe Its Saurian remains Character of the sedi- ments Divided into five stages The Lias has three groups The Wealden closes the epoch 198 CHAPTER XVIII. Cretaceous System Characteristics of the Mesozoic Division Derivation of the name Cretaceous Lower Division The Green-sand lithological characters Fossils of the Green-sand 203 CHAPTER XIX. Cainozoic Division General characteristics of this division Sir Charles LyelPs subdivisions of the Tertiary Eocene, Miocene, and Pliocene, &c. ....... 209 CONTENTS. XI CHAPTER XX. PAGE Glacial or drift period 246 CHAPTER XXL Post-glacial beds Alluvium Eolian Sands Bottom Prairie Bluff and River Terraces Coast Sediments Cavern Deposits Travertin Coral reefs Volcanic productions 254 CHAPTER XXII. Volcanoes, volcanic action, and earthquakes 259 CHAPTER XXIII. Mineral veins Veins of rock or earthy matter 264 CHAPTER XXIV. Mean elevation of land Ocean level Disturbances, or dislocations of the earth's crust Epoch of some of the most important dislocations Gradual and paroxysmal elevations Relations of land and water Changes of temperature induced by a change of relations, and effect on the distribu- tion of plants The relations of igneous rocks to disturbances of the earth's crust * 267 CHAPTER XXV. Soils * 271 MANUAL OF GEOLOGY. CHAPTER I. KNOWLEDGE AND ITS DEPARTMENTS. CHARACTERISTICS OF MAN AND THE PROGRESS OF KINGDOMS. 1. The sum and substance of all knowledge is derived from the observation of Phenomena, and whatever we know of matter or mind, becomes our property through phenonema; or, what may be regarded as expressing the same thing, is ours, through and by associated facts of which we become conscious by our mental operations. Knowledge becomes Science, when the phenomena of existence are so far known, that they may be classified; or when they are so far known to us, as to enable us to express ultimate results or fixed relations. Mind, is that which thinks and wills and is also emotional; Matter, is that which is known to us through the medium of the senses; and hence, knowledge is divided into two great depart- ments : one relates to Material bodies, and the other to Immaterial existences. These constitute the two great fields of human research ; the first is usually called Physical, and the last Metaphysical science. Both however, are prosecuted through and by the intervention of phenomena, and belong equally alike to existences in nature. They include together the facts of all existences, but are properly sepa- rated as their fields are dissimilar in kind, though both are con- cerned with phenomena and cannot be investigated without them. 2 . Physical Science, usually called Natural Philosophy, takes in its domain all the phenomena of external nature, or all substance which 2 (13) 14 MANUAL OF GEOLOGY. is recognisable by our senses. But its domain is so wide, that it becomes necessary to subdivide the field into minor areas, each of which comprehends distinct and separate branches of science. These have received appropriate names, which have been applied according to the nature of the subject-matter they include. The first and most comprehensive division is based upon the presence or absence of the principle we call Life. This leads us to form two great divisions of matter, one of which is called Organic and the other Inorganic matter. 3. The phenomena of organic bodies are comprehended under the terms Zoology and Botany. They are also called Kingdoms. The former includes in its domain, the associated facts which relate to Animals, and the latter, those which relate to Plants. 4. Inorganic matter includes in its field all that belongs to the earth and heavens, not included in the former divisions ; it there- fore comprehends Astronomy, Geology, Mineralogy, Chemistry, &c., together with the consideration of those forces which belong to each respective department ; or, in other words, the laws of celes- tial and terrestrial bodies. 5. Geology comprehends in its domain all the facts concerning the relations of the masses which compose the Earth, its structure, and the changes it has undergone in time : but a fuller statement of its objects will be found farther on. 6. Mineralogy treats of the individual objects which compose the earth, and the characters by which they may be known. 7. Chemistry has a special reference to the Composition of bodies, and the laws of Combination to which the elements are subject. It determines what bodies are Simple, and what are Compound, and in what ratios the elements combine. 8. Palaeontology combines in its domain the associated facts relative to Fossils, whether of vegetable or of animal origin, which are found in the sediments or rocks of aqueous origin. 9. The earliest condition of the foregoing branches of know- ledge was in that of isolated, or of disconnected facts. Their reduction to order and combination into, a scheme expressing gene- ral and fixed relations, elevated these facts into departments of science. * 10. Facts are accumulated by two methods, Observation and Experiment; but their arrangement and construction into systems is by a process called Induction, the facts and experiments consti- CHARACTERISTICS OP MAN. 15 tuting the basis by which the inductive process is executed. This process is generally defined, as that by which general laws are inferred from particular facts. The induction itself expresses the general result or law which is established from the consideration and bearing of the facts observed. It is evident, furthermore, that results or laws require in us a belief in the uniformities of nature ; or that like causes are followed by like effects. Without such a belief, or unless these uniformities existed, science would be impossible. Science, we may therefore state, is founded upon the uniformities of nature, without which our observations would be of no avail, and our experiments would be useless. 11. The explanation of effects is accounted for, in general, by referring them to something which, so far as we know, constantly pre- cedes them ; and that which precedes, is said to be the cause. But, then, it is customary to speak of two kinds of causes, Physical and Efficient. The former is the law itself, as the fall of a stone to the earth is referred to the law of gravitation. The latter implies intelligence, and is referred directly to the Divine will. 12. In investigating the facts of all existences, it is necessary to recognise the presence of both forces and agents. It is by them that the uniformities of nature are usually expressed. What is called Gravitation is an example of an universal force, and the law of the movements of bodies is expressed by well-known formulas, while Affinity is a force which affects the molecules of matter, and disposes them to combine in definite ratios. 13. Agents are physical bodies. In geology, for example, it is necessary to recognise the agency of fire and water. Their effects become evident to the senses, and their operations are extremely varied. The action, of particular forces is inferred from effects or consequents. 14. The kingdom of inorganic matter stands out prominently by itself, and is evidently subjected in itself to the action of physical forces only. These are its highest endowments. The first step indicative of progress, is in the vegetable kingdom, or in the domain of organic matter. Here, life in a low degree is engrafted upon organization, or is associated with it, and may be the formative principle of organization. It exhibits a great advance upon inert matter, especially when contrasted with the law of inertia. Thus the lowest condition of life appears first in the vegetable kingdom, 16 MANUAL OF GEOLOGY. where it is designed in part to evolve successive generations of beings, to clothe the earth, and furnish a supply of food for animals. The life of the vegetable kingdom is called Vegetative life; it is'simply nutritive in its functions. Another stage far in advance of this is Animal life; a concomitant of animals. By this kind of life, the world of matter becomes known to us through the medium of the senses. Vegetative life is a blank, or is blind. But animal life may be said to be engrafted upon what previously existed; for vegetable life still works in animals in the nutrimental sphere, precisely as it does in vegetables. There is nothing, there- fore, in the advance of kingdoms which is deposed. We also see that the advance of kingdoms is not by Differentiation, but by Incrementation. The latter expresses the law of progress in the kingdoms. 15. The highest concomitant of animal life in itself is intellectj embracing the knowing faculties, which are dispensed in different degrees, and are common to animals and man. But the crowning stage is exhibited in the sphere of man alone, for there is engrafted upon vegetative and animal life and its concomitant Intellect, Rea- son, and Conscience, with their concomitants also, which confer upon man the highest boon, immortality. 16. In all the foregoing stages of progress, nothing is deposed or dethroned. The physical forces, it is true, are for the time being overridden, but not left out. Vegetative life still performs its office in its own sphere. Intellect in man, though of a vastly higher grade than in animals, maintains its place, and the highest attri- butes we have named are the governing characteristics by which he should be classified. These, reason and conscience, are the attri- butes of his sphere, and place him above, and out of the pale, of the so-called animal kingdom. The life of reason and its concomitants, being engrafted upon the intellectuals, if progress is truly expressed, exhibits the kingdoms as completing their progress in four stages; advancing from the inertia of matter, through vegetative life, to animal life and its engrafted concomitants, then upward to the life of reason in the soul of man, becoming thereby the true character- istics of his being. 17. These stages are recognised in the geologic periods, and cor- respond with the succession of vegetables, animals, and man upon the globe : the kingdom of matter first, the kingdom of man last, the extremes of the geologic scale. CHAPTER II. CLASSIFICATION. 18. CLASSIFICATION is the Systematic Arrangement of bodies, according to the governing characteristics discoverable in their plans, forms, and structure. The process is performed daily by men in virtue of their possessing in their mental organization a classifying principle which can seize the governing ideas expressed in plans, forms, and structures. The idea contained in Classification is that of a separation of bodies into classes and subordinate divisions, each individual of which belonging to those classes or divisions, shall express one or more ideas common to each respective division. The foundation for the performance of this function, it can scarcely be doubted, is as much dependent upon the existence of governing forms and structure in "bodies themselves, as upon the possession of the classi- fying principle in us - } both are necessary, and it is important that we should especially feel that the foundation exists in nature ; for without this assurance we shall remain in doubt whether there is really in nature a regular plan upon which her works are con- structed. If there is a plan, it will be manifested by a series of characteristics or phenomena, expressed either in the outward form, or their less obvious inner structures. 19. All existences may be classified, but the bodies which con- cern us most are Animals, Plants, and Minerals. These if classified are denominated the Animal, Vegetable, and Mineral Kingdoms Each kingdom has its own principles of classification, notwithstand- ing the heads of the divisions are designated alike in case the divi- sions are admissible or founded in nature, Taking the animal kingdom first, as it furnishes the best illustration of a scheme of classification, it has been determined that there are four diverse branches or plans which were created to express so many modes of life which are compatible with the reigning external conditions of the globe. Each branch circumscribes all those existences which are constructed upon a certain plan. 2* (17) 18 MANUAL OF GEOLOGY. 20. These plans are expressed by the following terms. 1. VER- TEBRATA. 2. ARTICULATA. 3. MOLLUSCA. 4. B-ADIATA. It should be understood that these are not modifications of one plan, but that they are four distinct plans j and to determine whether a being belongs to Vertebrates (fig. 1), we have only to inquire whether it has a Spinal cord, or if to the Radiata, whether its organs are ar- ranged rad-i-ately at not. Respecting the first, we need not institute an inquiry as to the conditions of the protecting organ, whether it is bone, or a cartilaginous tubej the inquiry is, whether it has the CLASSIFICATION. 19 nervous organ, the spinal centre, or not. In the latter, the question is not put whether it has nerves or not; but simply into the radiate disposition of its organs. With respect to the Articulata (figs. 2 to 4,) F< *' 2 ' Fig. 3. Articulata. Fig. 4. Fig. 5. Mollusca. (Nerita Polita.) Articulata. Acidaspis. whether it has a jointed body and limbs, or of Mollusca (fig. 5), whether its body is soft, having a peculiar flesh like the oyster. Other inquiries are extraneous when the branch to which an animal belongs is the only question for determination. From the foregoing remarks it is evident that a branch of the animal kingdom has refer- ence solely to a plan, but not the details of a plan. The figure of the Lacamedea geniculata (fig. 6, p. 20), from John- son, shows both the closed and expanded vesicles of the polype, and also the radiated arrangement of the parts of the animal. They pro- duce in growth a corneous stalk which puts forth buds something in the form of a flower. It represents one of the orders of this 20 MANUAL OF GEOLOGY. great branch of the animal kingdom Radiata. In another type, the asteroid, the polype forms a stony skeleton, which is known under the common name of coral; Fig. 7 represents this order, which also belongs to the branch Radiata. Fig. 6. Fig. 7. Lacsmedea geniculat*. Corallum rubrum. 21. Regarding, then, the foregoing statements with respect to the four plans of organization of the animal kingdom to be estab- lished, we may proceed to the consideration of Class, which is the next division below that of branch. The word class, in this con- nection, means the highest and most comprehensive division which can be made in each respective branch. It is important to observe here, that the characters which are employed should have reference to the plan of structure, and be selected with a view to express the mode by which Nature executes or carries out her plan of organiza- tion, whether it be a vertebrate, or any other plan belonging to the kingdom. In each class, provided there is an harmonious system of construction, we shall find a ruling idea expressed in structure, or in the economy of their systems, which will run through the entire class, and in which we shall find an unmistakable similarity or homo- logy in each member, however much it may seem to differ in form In the first place, we propose to illustrate the preceding principle CLASSIFICATION. 21 by the Vertebrata. This branch, as now constituted, contains five classes : Mammalia, Aves, Reptilia, Amphibia, and Pisces. These have one characteristic ; all have the spinal cord. Now, on what grounds are these classes established, or by what characteristics are they so circumscribed that we have a right to distinguish them as classes ? We may demonstrate their right to this distinction and standing by the following characteristics : And, firstly, by the mammals. In this group, a system of organs has been provided for the temporary subsistence of the young. These organs are lactiferous glands which secrete milk, and which sustain for a time the newborn individual, or until it acquires the power and ability to provide for itself. This characteristic is wanting in the other classes. The name of the class expresses its characteristic in a condensed form. The selection of this characteristic is in accordance, too, with the principle already laid down It is a ruling idea, or a class character, being universal and essential in the economy of this great division of beings ; and besides, is associated with organs whose office secures the continuance of the species. It carries out the eco- nomy of the plan of the vertebrata. It is true, the mammals wear hair upon their skin, but this is a circumstance ; they could subsist without it ; but milk glands, with their appendages in this plan of organization, are made to express the most important idea of the class.* But the idea of the class is founded upon soft parts which * In one sense it is not the activity of the milk glands which constitutes a mammifer, for the individuals of this great family are born mammifers ; they are so prior to the time when they hecome essential elements in the animal economy. When we speak of predominating organs or elements in the structure or economy of living beings, our meaning is, that they are common or constant to the indi- viduals composing the branch, class, order, etc., in the adult state. Perhaps we might justly say, that which constitutes the essentials of a being is invisible, and inappreciable to our senses. The principle in the egg of a fowl, which evolves the fowl, is inappreciable, and is not dependent upon organs, because that would place the effect before the cause. The egg of a fowl evolves a fowl, and not a reptile, because it receives the principle which evolves it from the parent, and we can go no farther than to say that it is the gift of the CREATOR. The Creator imparted to each species its specific force, inappreciable to us, by and in obedi- ence to which each definite species is evolved in its sphere, and this gift secures the permanence of species for all time, and prevents their coalescence; while at the same time they possess certain flexibilities of character which enables them to conform to a range of circumstances which it was foreseen they would be subjected to; and hence these variables, as they may be called, are a part and parcel of family or of their specific characters. 22 MANUAL OF GEOLOGY. never exist in fossils; hence it is necessary to know more of the organization of mammals than it is possible to learn from the soft parts alone, and we must find in their bones those characters which belong to them as a class. Such characters exist and become available for this purpose; for example, the lower jaw of all mam- mals is in one solid piece, us seen in fig. 8. Whereas, the jaws of reptiles and fish are composed of many, as in fig. 9 ; besides Fig. 8. Fig. 9. Skull and Jaw of the Tiger. The molar teeth of mammals, too, have more than one root. Fig. 10 (see p. 23). Indeed, it is doubtful whether the reptile has molars at all, since the back teeth have only one root. (Fig. 9. A large back tooth elevated to show that it has a single root, as at a.) From the foregoing facts it will be seen that some of the details of the classes which lie at the foundation of the great divisions of the branches, exist both in the soft and hard parts of animals. The Zeuglodon (fig. 1 0) has a sauroid form, and was taken for a saurian when first discovered; yet its teeth, from their double roots and the convexity of its condyles, prove it to be a mammal. In the highest mammals there is always a complete series of molars, pre-molars, canine, and in- cisor teeth, as in the Chimpanse (fig. 11). There is also a wide space between mammals and birds. The latter have mandibles and no teeth : fig. 12 (see p. 24) ; the mandibles . ^ \ jaw of an Alligator, with It* sutures separating its pieces. CLASSIFICATION. Fly. 10. 23 Zeuglodon Tooth with its double roots. Fig. 11. of the eagle, or fish hawk ; but we know a family of mammals in New Holland which have the mandibles of a bird; but their feet differ from birds, and hence we take into consideration ,.^ the character of the feet (fig. 13, p. 24). It would occupy too much space to go farther into particulars and point out differences between the Mono- tremata and birds. It is more difficult to find marks which distinguish reptiles, am- phibians, and fishes, especially when we possess only organic remains. True reptiles, however, have only one condyle, whereas the amphibia have two (fig. 14, p. 25). A. showing the base 24 MANUAL OF GEOLOGY. Mandibles of the Fish Hawk. Fig. 13. of the skull of the Dictyocephalus, a rep- tile which belongs to * the Labyrinthodonts, all of which have also double condyles. Their bones, how- ever, differ in struc- ture, and under the microscope the re- mains of fish may be distinguished from reptiles by the form of the bone cell, which will be aoticed farther on. One of the distin- guishing characters of amphibians is their naked skin. They have neither scales nor plates, and be- sides they undergo a kind of metamorpho- sis which is unknown in the other classes. There is little diffi- culty in classifying animals as they are commonly presented to us. We may see at once the difference between a fish and a lizard or frog, a bird and a quadruped ; it is more difficult to point out distinguishing cha- racteristics where two classes approach each; or in the sauroid fishes, and certain saurians, especially where the student has to deal with mere fragments of fossils. These require careful study, and we have no space to devote to specialities of this kind. 22. Order takes the next rank below class. It is a subdivision of classes, and hence, it would be an error to employ those charac- ters which relate to the mode in which a plan of structure is carried out. It derives its characteristics from the details of the Foot of the Fish Hawk. CLASSIFICATION. 25 Fig. 14. / general organs, or the differences existing among them in each class respectively. For illustration, we may cite the class Reptilia a scale-bearing, and at the same time an air-breathing verte- brate. The class con- tains animals whose bodies are protected by a box or shield above and below, con- nected laterally by a bridge. These form one order in the class, and are named the Testudinata^T turtles. Another group of rep- tiles, that of tSauria, have elongated bodies, and a mouth furnished with teeth; and an- other, Ophidia, with vermiform bodies and destitute of feet, or Who employ their ribs. Labyrinthodont with its double condyle, a a. as a locomotive apparatus. All these modifications of structure illustrate modes in which the orders of the class differ; which differences constitute a basis for the establishment of the orders themselves. The ordinal characters being modes of expression, by which the class arrangements are carried out, we can scarcely fail to observe that they necessarily lead to many details of structure which are truly ordinal also. Thus, in the turtles, an important modification of the muscular system follows from the peculiar protection of the shield : no movements are required of the spine except of the neck and tail ; and those of the neck are executed in a mode quite peculiar. On the contrary, the extreme of the muscular arrango- 3 26 MANUAL OP GEOLOGY. ments exist in the serpents, whose spinal column is extremely movable, and whose locomotive apparatus requires a combination of spinal and costal muscles. The ordinal characters are to the class, what the class characters are to the branches; and from these and other considerations it is evident, that as the ordinal characters have a separate and distinct office, or indeed perform the highest functions of life in the individual; they are natural appointments. Formerly frogs, toads, and salamanders were placed in the class Reptilia, constituting an order. They have been separated, and now form a class denominated Amphibia. Their naked skins, and their metamorphoses, entitle them to the position they now occupy in our systems. They are inferior in rank to reptiles, and are more closely allied to fishes. But, to be more particular, Order may be illustrated, 1. by refer- ence to the class of birds. Some of the details which express ordinal characters will be found in the variable forms of mandibles and the locomotive organs the legs and feet. Thus the birds of prey, the Raptores, have sharp hooked bills, and feet with sharp claws for seizing and holding their prey, as in fig. 12 and 13. The order Scansores, or climbers, have straight and somewhat wedge- form bills of great strength, and feet with four toes ; two before and two behind, which fit them for climbing, as in figs. 15 and 16. The order Natatores, Fig. 15. Fig. 16. or swimmers, have feet wholly or part webbed, as fig. 17. Another order, the Grallatores, have long naked legs, fit- ted for wading, as the Herons. They have long sharp tri- angular bills for seiz- ing fish ; others have slender bills for exploring the mud Bill of the Woodpecker. Foot of the Woodpecker. for WOrmS, aS in the Snipe, fig. 18. The foregoing embrace some of the details relative to some of the orders in the class Aves. These may be said to CLASSIFICATION. 27 Fig. 17. Fig. 18. Foot of the Duck. include the most important details belonging to the class. Mollusks are divided first into Mollushs proper, as snails, clams, oysters, &c., and Bryozoa ; the latter of which furnish certain general resemblances to the radiata, as in fig. 19. But their digestive organs are Fig. 19. Fig. 20. Snipe. molluscan, their ori- fices for the recep- tion of food and the discharge of excrements are dis- tinct, as at d; a being the oesopha- gus, and their mi- nute cells are not septate, as in the polypes. The first and highest order of mollusks are the Cephalopoda, as re- presented in fig. 20. Their feet or arms surround the head and are provided with suckers. The Gasteropods move upon a broad foot, placed usually beneath, as fig. 3. The Pteropods have their organs of locomotion wing-like and placed upon the sides of their heads, as fig. 21. The Tunicata are soft animals, or without Cephalopod. Octopus hawaiensis. 28 MANUAL OF GEOLOGY. Fig. 21. Fig. 22. Pteropod. Creseis subulata. Fig. 23. live in families. They are enclosed in a sac, and have never been found in a fossilized state, Fig. 22. The arrows represent the course of the food. The Bracliiopods, or Pallio* Fig. 24. Spirifer striatas. Fig. 25 branchiata, are equally distinct, as an order, from the preceding. They are inequivalve bivalves; a large valve being applied over the abdomen and a small one to the back ; and hence are distinguish- ed as ventral and dorsal valves. The former has often a perforated Lingnla anatina. Atrypa retlcnlaris. CLASSIFICATION. 29 beak from which issued a byssus by which the animal attached itself to some foreign body: fig. 23 shows the attachment of the Lingula, a genus of this order. The mollusks of this order were also 'supplied with an internal cal- careous skeleton in the form of coils, loups, &c., as represented by fig. 24, showing the spiral of the genus Spirifer (Spirifer striatus), and fig. 25, the spiral cones of the Atrypa reticularis. Some of the genera of this order were free : that is, they were not attached to a foreign body. The Brachiopoda are the most ancient mollusks known ; they began their existence in the oidest sediments, and have continued down to the present epoch. Fig. 27. Fig. 26. Gasteropod. Tritonium Anglicum. Cytherea. Acephala. We should not pass over the common divisions of mollusks into univalves and bivalves, or with shells consisting of one and two valves (fig. 26 and 27), the Cytherea, fig. 27, with its palleal line 3* 30 MANUAL OF GEOLOGY. Fig. 28. forming a sinus, as in the upper valve, upon the left, and its two muscular impressions placed at the extremes of the line. Other bivalves have the palleal line continuous and without a sinus ; and as to the muscular impressions, many have one only, as it is seen in the oyster and scallop. The fish were divided by Agas- siz into four orders, being go- verned by the form, structure, and composition of the scale. Fig. 28, a, the ganoid scale, of a rhom- bic form, and covered with enamel ; fr, the placoid scale, furnished with hooks the Heterocercal Tail. Homocercal Tail. ctenoid scale of the perch ; d, the cycloid .scale of the shad ; the two last kinds are corneous and flexible. The two former belong mostly to ancient fishes ; the two latter are comparatively modern, and did not appear until the cretaceous period. The form of the tail of fishes furnishes important characters. The organ is divided into two lobes. When the upper lobe is larger than the lower, it is said to be heterocercal, fig. 29 : when the lobes are equal, or nearly so, or the spinal column terminates at the base of the lobes, it is homocercal, as in fig. 30. 23. In proceeding from the more to the less general divisions, it is maintained by distinguished naturalists, that, family naturally succeeds order ; that families are often groups under an order, cir- cumscribed by characteristics more or less well defined. A-assiz confines, however, family characteristics to form, not simply shape, but form, growing out of structural peculiarities ; still, the mean- ing is closely allied to shape, which is due to the proportion of parts ; or it may be expressed by saying, that it is due to the rela- tive developments of parts, as to size and position, and hence, the CLASSIFICATION. 31 Fig. 31. Fig. 32. Fig, 33. Bos. insectivora. Cervus. Herbivora. Dromatherium. characteristic is one of likeness dependent on form and proportion of parts. As such characteristics strike one at the first glance, it is evidently an outward character, and distinguishable without the necessity of dissection. For example, the bodies of groups of turtles may be comparatively high and oval, or round or they may be depressed and circular each form would constitute, if the principles have been stated aright, families, under the order Testudinata. The families, however, as constituted under Mollusca by the most popular writers, do not seem to be founded on the principle of form alone ; and we may remark, that it is impossible now to restrict this characteristic to family botanists use it so constantly in specific descriptions, as, form of a leaf, seed, or root, &c., that it can scarcely be dispensed with. There are embryonic forms, and generic and specific forms ; as well as forms which are peculiar to rarieties. If the word form, is restricted by qualifications, its use will not lead to confusion in description. But if we substitute likeness for form, or relative proportion and position of organs, our error will be but trifling; for it is likeness which we seize upon at our first glance, and not form. 24. Families and sometimes orders, without family division, are divided into Genera. A genus finds its characteristics in what Agassiz has termed complication of structure. To us the expres- sion is obscure, but by reference first to several genera we may catch a glimpse of his meaning. In the class mammals we find the orders Carnivora and Herbivora : the first flesh (fig. 5), and the last '(fig 8 * 31 and 32), herb eaters; and hence their feeding is very diverse, and their masticating and digestive apparatus are necessarily dis- similar. But carnivora differ among themselves in certain organs. There are the genera, Felis, and Canis ; the cat and dog both are flesh feeders, and both have teeth adapted to the purpose ; but their number and characteristics differ. In flesh feeders the crown terminates in cutting edges, as in the tiger. Their eyes and feet 32 MANUAL OF GEOLOGY. differ, which differences become fitted to their habits. One is noc- turnal, the other not. One watches for its prey and seizes it with a bound; the other openly pursues until it is overtaken. Their class characters are the same : they are mammals. Their ordinal characters are alike : they feed upon flesh ; but then the number of their teeth, together with their forms, differ; the nails of their toes differ : in one they are retractile and kept sharp for tearing their prey. They differ in their whole economy, and these differences grow out of peculiarities of structure ; and these pecu- liarities are generic characters, or complications of structure, as called by Agassiz. The cat is a higher grade of carnivora than the dog. To make out a cat, we examine its eye, its form of head, which is in part due to large muscles, its teeth, its feet and claws, its shoulders, and those characteristics which grow out of the pecu- liarities of these organs, and we have the cat, or genus fells, any cat, but not a particular cat, as the cougar, lion, tiger, and domestic cat. The same may be said of Canis or Ursus, or the plantigrade animals. We find characters which circumscribe groups ; not indi- viduals, but much more than individuals. The Imectivora are closely allied to the carnivora. Their molars bristle with points, as in fig. 33. The Rodentia have two cutting teeth in front in each jaw, as the beaver, squirrel, and hare. 25. The last and principal division which succeeds genus is Species. It is defined abstractly by the late Prof. Morton to be a Primordial Organic Form. If the beings to which species have reference are taken into view, it may be defined, a " group of iden- tical individuals, each of which is the representative of the species." Morton's definition is open to the objection that, in certain ques- tionable cases, it is impossible to determine whether the form is primordial, or not. As it regards the latter, it is not agreed, and probably never will be, what differences in character are admissible without destroying the idea of identity. Those differences which are due to food, climate, or which are developed under new circum- stances, do not destroy identity even though they become heredi- tary. That differences do spring out of a combination of circum- stances and are transmitted to offspring, is admitted by all observers. But questions have arisen with respect to differences in beings which were acquired before the historical period, if acquired at all, and hence questions arise respecting their identity. One class maintaining that these differences are those which are primordial CLASSIFICATION. 33 or conferred upon them when created. Others maintain, on the contrary, that such differences have originated in the stock posterior to their creation, from a combination of circumstances, and are of such a nature as to become transmissible to their offspring. This view is maintained by facts of a similar kind, and on the ground that changes have taken place within the historical period equally remarkable. But the nature of a species, or the question what a species is, has been presented from another point of view, the potential point, as expressed by Dana, who in a communication to the Scientific Association, at its meeting at Montreal in 1857, maintains that species is essentially represented by force. Thus, in inorganic nature, hydrogen, an element, is represented by one, and oxygen by eight, and in all combinations of oxygen this number represents the species oxygen ; or, in case of combination of oxygen with hydrogen, the result, water, will be 8-j-l = 9, which last number is the resultant of the force of affinity. So also it is maintained, on the same ground, that force is at the foundation of the idea of species in the organic kingdom. The force, for example, of the germ-cell, developes the being with its organs successively ; or evolves by its force a new individual, that force operating as definitely and cer- tainly in each branch, class, order, genus, and species, as in the inorganic kingdom, where we can express the force arithmetically; and hence, in both kingdoms, the idea of species is based on " a specific amount of concentered force defined in the act or law of creation." A question may arise here, whether the idea of species, as maintained by Dana, is not something back of or behind the true one ; for instance, whether in the case of water, the true idea of the species, water, is not to be taken from water itself, rather than from 8-f-l j and so of organic beings, whether the resultant of the force of the germ-cell which evolves the new individual is not the species, rather than the evolving force or power which certainly lies back and behind the individual evolved. At any rate, there is a distinction between the evolving force and the resultant of that force; and, practically, the resultant is the object which furnishes the phenomena by which species are defined and circumscribed. A definition of a species belonging to the organic kingdoms cannot be fully expressed in a few diagnostic characters ; inasmuch as it involves genealogical descent and perpetual fertility; certain relations as to time and space, to duration and place, mental organi 34 MANUAL OF GEOLOGY. zation and unity of thought, food, habits, shape of organs, color and ornament. Where identity extends to, or includes all of these points, and we find them common to a group of individuals, we may pronounce those individuals one species. A species never changes into another species, for a very good reason ; it is derived from the germ-cell of parents, and hence is endowed with a, parental force. In order to effect a transformation of a species, it would require (if the expression is allowable) a new creation, or a new endowment unknown to the species, or, in other words, species in all cases are continued developments of germs, endowed with a specific force ; and hence a gerrn cell has no other force than that derived from the parent, or what it has received. Specific force is a constant in nature, imparted to a cell by previously existing beings ; and hence it is unnecessary to go into detailed historical observations, since we know that no organ- ism is ever developed independently of a cell, and which is univer- sally the product of parentage ; both history and physiology support each other upon this question. 26. Varieties originate in the individuals of a species, endowed with limited differences from the common type, which become permanent. The most striking varieties have sprung up under the influence of domestication, though in the vegetable kingdom they have been observed outside of man's influence, but not necessarily multiplied, or extending beyond the individual. The seed of varieties rarely reproduce the variety; it requires the cellular tissue as cuttings to effect a continuance of the variety; though in the cereals the varieties are propagated by the sexual organs. In the apple, pear, &c., it is the identical cellular tissue which is reproduced in the fruit by cuttings or buds, which is a part of the organization which is uninfluenced by the pollen. 27. Identity of character involves resemblance or likeness ; as the word resemblance is generally used, it lies at the foundation of classification ; for in every division it will be noted, that there are certain common resemblances existing in order to make out the large or minor divisions of a kingdom. There are, however, resemblances of two kinds ; one, which is proximate, and which belongs to individuals of one stock, or which is genealogical ; and another which is remote, and is really only typical ; it belongs to the type. In the first the resemblance is one of relationship, in kindred ; in the other it is simply typical CLASSIFICATION. 35 or of an approximate kind, there is no relationship. Specific character, it will be perceived, takes in a wide range of expression ; and there remains still one field of research for the exhibition of specific character, which is often of the utmost importance. It is the development of the embryo. The evolutions of the embryo in the same species are identical in all respects ; the force of the germ-cell evolves by law, and the respective changes indicate as certainly as possible the species ; for the changes or evolutions of the embryo have, at every stage, reference to species, not class, order, genus, but entirely to species. Hence we may employ em- bryonic changes as indicative of species; or we may employ the resultant of embryonic forces as indicative of species. If, how- ever, every stage in the evolution of the embryo points to the species, the resultant is not only representative, but is the species itself, and should be invested with specific attributes and characters. It is representative so far as class, order, and genus are concerned, but it is also in itself species, and any individual is invested with a representative character, which extends upwards through all stages of life, the specific, generic, and ordinal, ending in 'the branch to which it belongs. It has no relations except those of the highest kinds to the branches from which it is excluded on the ground of difference of plan of organization. A Synopsis of Classes and Orders belonging to the Animal Kingdom. The Mammals are divided into two sub-classes : the Monodelphic Mammifers and the Didelphic Mammifers. The first contains twelve orders. I. SUB-CLASS MONODELPHIC MAMMIFERS. 1. The Quadrumana, or monkeys. 2. The Cheiroptera, or bats. 3. The Insectivora, insect eaters. 4. The Carnivora, flesh feeders. 5. The Rodents rat beaver. 6. The Edentata, no incisive teeth. 7. Proboscideans elephants and mastodons. 8. The Pachyderms pig, hippopotamus. 9. Ruminants ox, deer. 10. Sirenoides, pisciform, and destitute of posterior members dugong. 11. Zeuglodon, only known in the fossil state; pisciform, teeth numerous j molars trenchant and denticulated. 12. Cetaceans, teeth conical or none, pisciform, destitute of posterior mem- bers whales, as thus explained, seems to assure us that it was the last element contributed to its surface from the surrounding space, that its accession added an important force antagonistic to that of fire, and that it has essentially modified its surface by its mechanical and chemical properties ; in fine, has been the principal agent in rendering it inhabitable by beings organized like man, and the lower animals. 51. It may also be inferred that, as seas must have been formed by continental rivers and their contents have accumulated gra- dually, so their saline matter must have increased slowly : hence, in the early existence of the planet, the oceans were less saline than now an assumption which seems to be sustained by the absence of salt in the oldest sediments, though they are all marine. CHAPTER V. OB GEOLOGIC FORCES FIRE AND WATER CONSIDERED AS AGENTS OF CHANGE DYNAMICS AND STATICS OF GEOLOGY. 52. THE forces which have been instrumental in giving form to the earth, as well as in arranging its subordinate parts, are two Chemical and Mechanical. And the agents immediately concerned are also two -fire and water. These are, however, generally spoken of as the forces of geology. The changes due to each are some- times chemical and sometimes mechanical. The first force brought into activity was fire. It was generated or first kindled by intense chemical action of the elements upon each other, when their atoms were brought together by condensation from that highly diffused state which we have referred to in the preceding chapter. The questions which relate to this nebulous state of matter, or hypo- thetical period, belong to astronomy. The geologist, however, has occasion to refer to it for the purpose of indicating the origin of those fires whose former existence seem to be established by the peculiar form which the globe has taken the crystalline state of all the inner deep-seated masses, and by the actual existence of fires within its crust at the present time. This present heat of the earth, we thus endeavor to trace back to its original cause; a cause cer- tainly adequate regarding it as the residual heat of the cooling globe, and not transient heat developed at uncertain intervals by the chemical, or galvanic action of the materials upon each other. Though these forces undoubtedly still perform important parts, they are at present rather the results of this heat than its sources. 53. In connection with the heated state of the earth, it is necessary also to consider it as a cooling body as constantly losing its temperature by the escape of its caloric into space. An envelope or crust consequently first formed, which has thickened by the loss of heat. This thickening of the first pellicle formed must be beneath, so that the crystalline covering of the earth (46) OF GEOLOGIC FORCES. 47 is a nether formed crust; the newest portion being nearest the centre of the globe. 54. In considering the time required to form a cool and stable surface, we must take into account the relation of the rocks to heat, considering them as good or bad conductors, and also the fusibility of different materials of which they are composed. 55. In the combined effects of heat, and of its escape, the geolo- gist recognises causes which are competent to elevate above the general level of the surface, portions of the earth's crust. And probably in ancient as in modern periods, these portions were raised in ridges, or formed chains of mountains similar to the Alleghanies, Alps, or Andes. 56. The effects of the fire force are also seen in the fusion and heating of strata wherever exposed to its action. It thus vaporizes water, disengages the gases from their compounds, and even vapor- izes sulphurets, phosphates, and other bodies that have metallic bases. 57. Vapors and gases being generated, they must either escape through fissures, or, being confined in cavities, they exert great pressure upon parts already fluid, or upon the solid crust. Pressure upon an incandescent fluid may force it through cracks and fissures, and on reaching the surface may flow over it and cover strata already consolidated ; instances of which are often witnessed in our day in the overflowing lava. The confined vapors may also force upward the crust, cause earthquakes, and permanently elevate that portion immediately above the place where they are confined. But it is maintained that mountain ridges are rather due to subsidence of the strata, by which the outcropping edge is tilted up, thus forming a ridge. The instances of change of level, however, in our times are accompanied by increased activity of the fire force, so that this agent is probably always concerned in the formation of single mountains, if not all mountain chains. Thus the Alia Bund, or Mound of God, in India, was raised during an earthquake, in 1819, ten feet high, sixteen miles in width, and fifty miles in length. 58. We trace, also, the origin of veins and dykes to igneous action. The rocks being rent asunder by the cooling of the strata, or upward pressure of the gases, a passage is opened for the water (from above), holding in solution various substances which may be deposited upon the walls of the fissures; or for the gases 48 MANUAL OF GEOLOGY. and vapors from beneath, consisting of the sulphurets and chlorides of the metals, or disengaged sulphur. The known laws of conden- sation of such bodies upon a cooled surface, would satisfactorily account for the filling of those rents with the metals and their compounds. The fissures called dykes were filled with melted matter forced up from below. Though the common effect of fire is to elevate the surface and force up melted matter, it sometimes undermines large areas and causes a subsidence. 59. The force of water is scarcely less important than fire in modifying the surface of the earth. It operates in four modes, viz. : by solution, by its expansion in freezing, by attrition, and by transportation. As a solvent, under common circumstances, it is not necessary to speak of it particularly. When it is aided by heat or pressure, it is much more important. If aided by heat and pressure together, it dissolves silica and many other substances, as is shown by the Geysers of Iceland and the waters of other hot springs, which upon cooling let fall the matter that has been dis- solved, so that in the course of time large accumulations form around the orifice where the waters issue. When it holds carbonic acid in solution, it dissolves carbonate of lime and iron, which it lets fall also when exposed to the atmosphere. The tufa about springs, and also porous oxide of iron, which are not uncommon deposits, are thus formed. 60. When water freezes it expands with great force. Rocks are thereby rent asunder by the ice formed in their seams; and all porous bodies, which absorb water abundantly and afterwards freeze, are broken up and reduced to soil. It is however much more important as a mechanical force, when acting as a transporting agent. As it flows in streams and rivers from the mountains to the oceans, the debris which is committed to it is carried along to these great basins. It is estimated that the Mississippi bears down sediment enough annually to form a stratum one foot thick and 12 miles square. The tide wave impinging upon shores, and flowing into harbors and up rivers, transports sediment during its ebb, and as it pursues outward its course, deposits it' at all points where its force is diminished by obstructions. A bar is formed where it meets river currents, and hence the navigation of rivers is often obstructed. The Atlantic tidal wave is both constructive and destructive. It is more destructive when its force is aided by winds. The waves which break upon the shores cast up sand, OP GEOLOGIC FORCES. 49 a part; of which is often blown inland, making desert and sterile large areas which lie in the course of the prevailing wind. Another portion of the land is often raised into a ridge nearly parallel with the shore line. Such ridges often form along the shore of inland lakes, and have been mistaken for moraines. 61. The great ocean river, known as the Gulf Stream, is a still more important flow of water. It is a bearer of both heat and sediment. That portion of the great equatorial current between Africa and America, impinges upon Cape St. Roque, in Brazil; then flows onward into the Mexican Gulf, where it is heated to 88 F. ; then passing out by the Florida Keys, it flows N. E., and finally approxi- mates the north-western coast of Europe. It parts with its heat, which is distributed by the prevailing westerly winds over the western and north-western coast of the Continent. During its progress the fine sediment it received from the Amazon and Mis- sissippi, is distributed along its course upon the ocean's bottom. 62. The vastness of the scale upon which water operates, is indi- cated by the extent of ocean surface. Thus, the Atlantic has an area of 25,000,000 of miles; the Pacific 70,000,000; while the earth has only 35,000,000. Fig. 42. 63. From the foregoing statements, we may perceive that the sediments which are transported by water to the ocean are the materials of a large class of rocks, which it is evident may be recognised by the earthy character which they must assume, and the intermingling of such debris with various kinds of organic matter. Water in the act of transporting the debris of rocks, whether fine or coarse, must necessarily bring this matter into col- lision with rocks and with its own moving particles : hence, most matter thus transported bears evidence of the attrition to which it has been subjected; and the rocks bear external evidence of their origin, though the limestones, which seem to have been, in part at least, in chemical solution, are frequently crystalline, and in this condition their sedimentary character may be disguised. The winds are important agents in producing geological changes. Evaporation goes on continually. From oceans, seas, rivers, lakes, and the surface of the earth, vapors of water are ever rising, borne by winds over the highlands and mountains of continents ; it is there condensed, and falls in the form of rain, or snow, affording a never-failing supply of water for mountain streams and continental 5 50 MANUAL OF GEOLOGY. rivers, to flow on back to the oceans and large bodies of water, and to rise again in the form of vapor. Great changes are effected by this circulation and interchange. Slowly, but surely, the hardest rocks are worn down and softened ; the surface of the whole earth is modified ; debris from the mountains and hills is carried down and spread out over the plains, or the c * 55. reptile of the nineteenth cen- tury : fig. 55, bone cells of an ancient fish : fig. 56, 1, bone cell of a recent fish: 2, of ai reptile : 3, of a bird ; 4 , of |j a mammal. There have been myriads of organic existences, yet there has been no deviation in the patterns of structure. In all the ancient or extinct beings, the pattern has been followed through- out in the modern ; and hence to find original types we have to go back; and our language should in- dicate a comparison of the pre- sent with the past, and not the past with the present. To preserve these uniformities, as they exist in the primordial types, required one wiU. This is the essential of uniformity. These structures are the real constants of organization, as much as the determinate forms of crystals are the constants of the inorganic kingdom. 112. We should not conclude our general remarks upon the sedi- ments, without offering our views upon Metamorpkism. Thus, rocks which are truly metamorphic are either connected with those of igneous , origin, or erupted ones; or else, their relations are such that geologists are furnished with a clue to the cause or causes which were operative in effecting the changes which they have suf- fered. It is at the same time true, that changes, to a limited extent, have taken place without the instrumentality of a visible agent. It is often necessary in these cases, to refer them to a general prin- ciple or law, which has been frequently referred to in this work as a molecular force. It is under the influence of this force, that particles composing the sediments are rearranged; limestones, for example, pass into a crystalline condition, and the slates are cut up into tabular plates of a rhombic form, &c., a fact ; which may Bone Cells of Fish, Reptile, Bird, and Mammal. 80 MANUAL OF GEOLOGY. often be accounted for on the ground of great pressure and the influence of a molecular or crystalline force. Metamorphism is no doubt due to two principal causes : heat derived from the interior of the earth or the presence of eruptive rocks, and molecular force aided by the presence of water. Water is probably always present in sediments, and to its presence is due in part, the mobility of their particles; indeed we have reason to believe that a mass may exist in a semi-plastic state, in consequence of which a re-arrangement of the particles will take place. Crystallization will then occur. Hence, many of the lime- stones are coarsely crystalline. Another class of rocks have been called metamorphic, which are scarcely entitled to the appellation. We refer to those into which talc and mica enter largely as consti- tuents. In rocks thus constituted, we have no occasion to infer that the mica or talc has crystallized from the mass ; it is rather to be inferred that they are simply derivative, and exist in the condition they originally were in the parent rock, excepting that their size has been diminished by attrition. Fig. 57. Paradoxides ? quadrispinosus of the Tacouic slate*, CHAPTER XL TACONIO SYSTEM DIVIDED INTO UPPER AND LOWER FOSSILS OF BOTH DIVISIONS. 113. THIS system* deserves the special attention of geologists for two reasons : 1st. It is probably the base of the Sediments ; 2d. It is also probable, that it is the Palaeozoic base, and, in both respects, it must be regarded as the oldest series of the sedimentary class. As mechanical sediments, they should, as a whole, bear more than any subsequently formed rocks, the aspect of the primary or pyro-crystalline ones; especially those beds which were first de- posited. Such is the case : it is difficult to distinguish them from the rocks from which they were derived. This is particularly so with those members in which talc and mica are intermingled. As the Palaeozoic base, it is interesting from the indications the sediments furnish of the condition of the earth at the time when plants and animals were first created, and also the peculiar forms which peoplejl it in the dawn of their existence. At this period we have reason to assume, that the temperature of the earth was higher than it is now; but not to that degree as to be incom- patible with the life of animals as they are now constituted. It is evident from the disturbances to which these rocks have been subjected, that the earth's surface was subject to great oscillations, and that chemical forces acted with considerable energy, probably greater than at any subsequent period. This system has been called metamorphic, probably with more propriety than any other ; yet there is scarcely in any case so much alteration or change in the masses composing it as to disguise * It is proper to state that several distinguished Geologists have regarded this system as the Lower Silurian; or as the equivalent of the Champlain group. According to their views the quartz rock of Berkshire is the Potsdam sandstone more or less altered by heat; the Stockbridge limestone is the Trenton lime- stone; and the slates crowning Graylock, the highest land in Massachusetts, are the Utica and Hudson River slates in an altered condition. This locality is the spot selected with a special reference to prove the foregoing doctrine. (81) 82 MANUAL OF GEOLOGY. their sedimentary origin. The lower limestones have lost, to the greatest extent, the peculiar phase which belongs to this class of rocks: The silicious rocks are often vitrified, or have lost their granular structure in a measure. Regarding this period as one during which the mechanical and chemical forces were very energetic, we are, no doubt, furnished with a key to the solution of all the phenomena of this kind. At this period thermal springs were, no doubt, far more numerous than at present, and many of them held in solution large quantities of silex, which, when deposited, passed into the condition of vitrified masses, identical with the beds of chert and hqrnstone which is one of the common rocks of the system. It is by no means necessary to conceive a high degree of temperature common to the whole sur- face of the globe, but that the surface had so far cooled, that the water had accumulated in oceans and seas, and that waters of high temperature were merely local phenomena as now, being however more numerous and upon a larger scale. The fossil vegetables, which belong to this series, are exclusively marine ; in the upper part they are numerous. 114. The animals belong to three great divisions of the animal kingdom : Articulata, Mollusca, and Radiata. They represent the lowest forms of their respective types. Thus the articulata are represented by Crustacea belonging mostly to the genus Paradoxides; the mollusca are either Brachiopodes, or those which are related to them, and very small; and the radiata are the lowest forms of Polypes, and are similar to the recent fungites. The fossils of this system are, therefore, of the lowest rank; they are also rare. It has been maintained, that the rarity of fossils was due to the condition of the rocks ; that, although they may have been as numerous as in the Lower Silurian series, yet, the rocks having been altered by heat, the organic remains were obliterated. But, unfortunately for this view, it is found that the parts of the series, which cannot be regarded as changed, are equally as barren as those which are located near the primary, and which are in the immediate region of metarnorphic action. It is, therefore, probable that the paucity of organic remains, in this system, is due to the fact that it was not a period abounding in living beings. While those which are found are interesting, because in the present state of our knowledge they are the first which appeared TACONIC SYSTEM. 83 upon the globe, they belong to types which are well known in our present seas, notwithstanding they are so far removed in time from the present. This confirms what we have maintained, that, in the almost innumerable forms of organic remains which belong to the different periods of the earth's history, none are known which do not belong to one of the four Cuvierian types, which are so fully represented in the living fauna of recent times. The unity of the plan of creation is most fully confirmed by facts which are drawn from this most ancient sedimentary epoch. 115. The distinguishing features of the rocks of this period must be obtained from the lithological characters of the rocks themselves, and from their relative position. They are conglome- rates brecciated conglomerates : sandstones, limestones, and slates, among which it is common to find cherty masses of considerable thickness intercalated. The important minerals which belong to this period are gold, silver, specular oxide of iron, haematites, and manganese ; galena is sometimes found. 116. This system is subdivided into Lower and Upper', the first consists of a conglomerate at the base, succeeded by silicious tal- cose beds of considerable thickness, in which there are frequently pebbles ; next above, are three thick beds of sandstone, separated by talcose slates ; these are succeeded by the Stockbridge limestone. This is the marble of Berkshire county, Mass., and which extends from the state of Vermont to Georgia. The Stockbridge limestone is succeeded by a mass of slate of great thickness, the upper part of which is suitable for roofing. The greatest thickness of the Lower Taconic rocks is about 5000 feet. The upper quartz beds are often vitrified, while a lower one, still many hundred feet nearer the pyro-crystalline rocks, is a sandstone. Fig. 58 illustrates the Berkshire masses. This section begins with the lowest beds resting on gneiss and granite, and extends across the summit of Oakhill in Williamstown, Mass., and west through the valley to the Petersburgh range. 1. Conglomerate at base. 2. Limestone. 3. Slate. 4. Conglomerates. 5. Slates. 6. Sparry Limestone. 7. Slates. C. Overlying Calciferous Sandstone. ////. Fractures. The section fig. 59 is designed to illustrate the equivalent beds in Buncombe Co., N. C., near the Warm Springs. The conglo- merates upon this section are much thicker than in Berkshire Co., and the lower Taconic is much more perfectly developed, and the quartz is much more vitrified. The materials composing the con- 84 MANUAL OF GEOLOGY. glomerates in each section are derived from the pyre-crystalline rocks upon which they rest. 117. The Warm Spring Section, N. C. ; fig. 59, exhibits the following series : a. Gneiss, b. Sienitic Granite. 1. Talcose Slates with pebbles. 2. Seamy Brown Sandstone, more or less ferruginous. 3, 4, and 5. Slate with Pebbles. 6. Talcose Jointed Slates. 7, 7, 7. Talcose Slates. 8, 8. Granular quartz. 9. Gray Limestone. Section fig. 60 is designed to show the position of the granular lime- stone of Berkshire Co., near Graylock, Williamstown, Mass. This rock crops out upon both sides of Saddle Mountain. 1. On the western slope facing the valley of Green river. 2. On the Adams side of the same range, and hence forms a low synclinal axis. Above the limestone, which is about 300 feet thick, is a thick mass of talcose slate ; below it, is another very thick mass, lying between it and the granular quartz. Hence it will be perceived that these masses do not co-ordinate with the Lower Silurian or Cambrian. 1. Quartz. 2, 2. Limestone. 3, 3, 3. Slates above and beneath the limestone. C. Taconic range. B. Saddle Mountain. The foregoing sections represent the relations which these masses hold to each other throughout a continuous belt extending from Canada to Georgia. The Lower Taconic series appears at Edgehill, Pa., where a whitish sandstone succeeds and overlies the gneiss. It is as usual interlaminated with slates, in which talc predominates. Lime- stone succeeds northward, but the series is soon concealed beneath the Permian and Trias. The Lower Taconic is also crossed by the Pottsville Railroad, near Norristown. This lower sandstone is usually underlaid by a conglomerate, but at neither of these cross- ings is this important mass present. 118. Upper Taconic Rocks, consist of numerous beds of slate alternating with shales, thin-bedded sandstone, some of which are coarse and brecciated, thin-bedded bluish limestone, more or less cherty and checked with seams of white calcareous spar, and red, brown, and purple roofing slates. The following section extending from Comstock's landing on the Northern Canal, New York, to North Granville, shows the relation of the upper beds to the Lower Silurian. The description of the Silurian is in the ascending, and of the Upper Taconic in the descending order. 119. a. Gneiss : Comstock's landing. 1. Potsdam Sandstone. 2. Calciferous Sandstone. 3. Chazy Limestone, a. Slates interstratified with fine grits belong- g to the Upper Taconic beds. 6. Slates overlying a mass of chazy limestone. Fig. 58. TACONIC SYSTEM. Fig. 59. Fig. 60. 85 Fig. 61. Williamstown Section. 86 MANUAL OF GEOLOGY. c. Thin Sandstones, d. Uneven-bedded Slates and Shales, c. Thin-bedded Sparry Limestone. /. Bluish Slaty Grits, g. Coarse Calcareous Sandstones, i Gray Sandstone, k. Flags containing marine plants. I. Cherty Sandstone, m. Blue Slates, n. Sparry Limestone, o. Blue, red, and purplish roofing slate of East Granville, containing a single bed of sparry limestone 3 feet thick, p. Hard, thick and thin bedded coarse grits, q. Brick red roofing slate 200 feet thick, r. Slates and coarse grits alternating with sandstone and with brecciated beds sepa- rated by tine bluish slates. These lower beds are well exhibited in Grafton Mountain, Rensselaer Co., N. Y., and at Bird Mountain, Vt. The red slates pass through Granville Four Corners. A similar section may be traced in Wythe Co., Va., but the limestones are much more largely developed. At North Granville, N. Y., the overlying Lower Silurian lime- stones with their fossils are perfectly plain at numerous points. Fig. 61 : 1,1. Successive beds of the Taconic series. 2. Calci- ferous sandstone. The outlyers of Lower Silurian often occupy troughs in the slate, and frequently deceive the observer unless aware of the fact ; as at 2, 3, 3, 3, beds of calciferous sandstone. Fig. 62. 120. Tie fossils of the lower beds are limit- ed to one or two species of corals, and, so far as discoveries have been made, these are confined to one region, though there are many locali- ties; but the indivi- duals are extremely numerous ; these locali- ties are in Montgomery Co., N. C. ; and the beds are located about midway between the top and bottom of the quartz rock. The Palceotro- chis, the name of the fossil in question, fills some of the strata and is associated with concretions, some of which envelope the fossil wholly or in part. The concretions take the form and size of almonds, and are usually formed of concentric layers. 121. Fossils of the Upper Series. They consist of marine plants, the lowest forms of animals, as graptolites, and several species of articulata. as trilobites and worm tracks. \ Palseotrochis Minor. Fig. 63. Palaeotrochis Major. Fig. 64. TACONIC SYSTEM. Fig. 65. 87 Fig. 66. Diplograpsus ciliatus. Enlarged. Worm Tracks. Fig. 67. Fig. 68. Fig. 69. Diplograpsus Fo- liosus. Enlarged. Staurograpsns dichotomus. Enlarged. Diplograpsus rugosaus. Fig. 64. Worm tracks of the Waterville Slates (Nereites Deweyi). Fig. 65. Diplograpsus ciliatus. Fig. 66. Diplograpsus secalinus. Fig. 67. Diplograpsus rugosus. Fig. 68. Diplograpsus foliosus. Fig. 69. Staurograpsus dichotomus. Fig. 70. Para- doxides asaphoides. Fig. 71. Atops punctatus. Fig. 72. Obolus? Microdiscus quadricostatus (enlarged). Fig. 73. Fig. 74. Lin- gula striata. The two last are minute fossils. According to Barrande, the Paradoxides and Olenus belong to his primordial zone, or are Sub-silurian in Bohemia. In this respect our paradoxides are also Sub-silurian j and hence it has been shown MANUAL OF GEOLOGY. Fig. 70. Fig. 71. Paradoxides macrocephalus. Fig. 72. Fig. 73. Fig. 74. Mic rod i sous Qua- dricostatus. Enlarged. 75. Unconformity of the calciferous sandstone a, with the Taconic slates, 6. TACONIC SYSTEM. 89 that the primordial zone in Bohemia is in co-ordination with the upper series of the Taconic rocks. The range of country through which this series passes is the western face of the Green Mountains, extending from Canada to Georgia. These rocks cross the Blue Ridge at Harper's Ferry, or in its vicinity. They occupy also a range of hills or mountains, east of Wytheville, Va., extending westward to the immediate vicinity of the Queen's Knob, where they face unproductive coal measures. The series also passes along the eastern flanks of the Green Mountains and Blue Ridge, passing through the eastern part of Virginia and North Carolina, and onwards into Alabama. Upon this belt are numerous gold, copper, and iron mines in veins and beds. The same series occur upon Lake Huron and Lake Superior district, and also in Arkansas in the vicinity of the hot springs. This series is developed on the Ocoee river in heavy beds of conglomerates, slates, and grits. Prof. Safford refers some of the rocks upon the French Broad in North Carolina and Tennessee, the rocks forming the ranges in Sevier County, to an Azoic or Sub-silurian sys- tem. Prof. H. D. Rogers distinctly defines a zone of sediments which he regards as semi-metamorphic, and which occupies a broad belt south of the limestone valleys of the Conestoga and Codorus streams in Lancaster and York counties. This zone, however, belongs to the Lower Taconic series, if his description can be relied upon. Prof. R. applies the term Azoic to these Sub-silurian deposits, a term which is inadmissible when applied to sediments.*" The Taconic series, especially the lower division, furnishes many fine exhibi- tions of displacements and inversions of strata. Of the latter, Stone Hill, an emi- nence south of Williams College, is an interesting example. The hill is about 500 feet above the Hoosick river. Its strata dip to the south-east ; but the oldest layers repose upon the newest, so far as those composing the hill are con- cerned; or, in other words, they have been forced so far over that the original bottom beds occupy the uppermost position. Many contorted strata occur, exhi- biting remarkable cases of lateral pressure. * See Note A, page 280. Fig. 76. CHAPTER XII. SILURIAN SYSTEM GENERAL STATEMENT OP FACTS RELATIVE TO ITS EPOCH DESCRIPTION AND DIVISION OF THE MEMBERS COMPOSING THE SYSTEM, ITS FOSSILS, ETC. 122. THE Silurian system, which fills so large a volume in the geologic history of Europe, seems to be still more full and complete in America. It extends from Canada on the north, to Alabama on the south. The Adirondacks, which bulge up, and form, as it were, a great but irregular dome, throw off the oldest sediments of the system in all directions, but more especially in two : one towards the north-east, and the other towards the south-west. The dip of the rocks, on the north-east side, indicates the existence of a great and widely spread-out basin in this direction, which might be called the Lawrentine Basin of the system. Following the dip to the south-west, the indications are equally clear that, in this direction, too, there is another basin of a vast extent having its south-eastern base in the Appalachian Mountains, and, hence, might be called the Appalachian Basin of the Silurian system. These basins are separated by an anticlinal axis, which is very clearly marked by the Highlands of Northern New York. A rough measurement through both basins, over this anticlinal, gives us at least a distance of twenty degrees of latitude. Following the base of this system from the northern extremity of Lake Champlain to the St. Lawrence, and then tracing its course along the irregular borders of the great lakes to the waters of the Mississippi above the Falls of St. Anthony, we shall find its extent, in this direction, not less than 1500 miles. A peculiar feature belongs to both basins, especially the south- western one. It consists in the remarkable regularity of the suc- cession of its strata. These wide areas are scarcely broken by igneous injections; and, hence, the regular succession of strata is rarely interrupted or displaced by outbursts of the pyro-crys- talline rocks. This freedom from breaks and interpolated igneous masses had (90) SILURIAN SYSTEM. 91 aD important bearing upon the regularity of the succession of its organic stages ; and, hence, secured the most favorable condition for the preservation of life; and to this we may attribute the per- fect representation of these stages during the whole Silurian period. The two facts seem to harmonize so well that they may be related to each other as cause and effect. From the foregoing it will pro- bably follow, that the time, when important species were created, may be more exactly determined ; and so, also, may the time of their extinction become a matter more easily settled, than if the areas, over which they are spread, were broken and dislocated by frequent eruptions. The history of the Palaeozoic period will, therefore, be more complete, and at the same time more interesting for its mani- fold developments of organic beings. It is in this system that life begins to assume a supremacy over dead matter. All the great branches representing animal life appear in this period, though not in perfection. It is mainly the lower ranks of each branch respec- tively, which appear in this system. It might be called the Pro- phetic system. It is all important that the student should be informed, that, with respect to American systems of rocks, we have, as yet, been unable to make out that their subordinate parts have, in all instances, their synchronisms in the European systems of the same name. We can identify certain subdivisions; but there are many breaks between the subdivisions, which have not as yet been shown to be synchronous. It will be well to prove, if possible, that our formations are parallel with well-known European ones ; but nothing is gained by assuming it to be the fact in the absence of proof. The American continent has its own history ; and we have reason to believe that, in many respects, especially in its details, we shall find it to differ from that of Europe. Hence, it should be worked out independently of foreign bias. It is, no doubt, true, that, as great masses, there is a close connection in the Ame- rican and European divisions ; and, in many instances, it exists in the subordinate parts, and some of the breaks are synchronous ; others are not yet proved to be so. 123. -Subdivisions of the Silurian System. The Silurian system may be divided into Lower, Middle, and Upper: Lower Silurian, Champlain Group, or Cambrian. The oldest member of this divi- sion is a sandstone of a red, gray, or chocolate color, and sometimes white. It is the Potsdam sandstone of the New York survey. The 92 MANUAL OF GEOLOGY. Lingula antiqua. Fig. 77. bottom is a conglomerate. Its greatest thickness is about 800 feet. It contains a lingula, fig. 77, and two or more species of trilobites. The next in succession is the Calciferous Sandstone, being a mix- ture of carbonate of lime and fine grains of quartz. In color it varies, but usually is of some shade of gray. Weathers to a drab color. It is sometimes oolitic, as at Chazy, or concretionary, as at Little Falls. Its fracture is uneven and sparkling. The middle and upper parts are cherty, and contain much magnesia, and has been called magne- sian limestone ; it contains quartz crystals and solidified bitumen ; the latter is often enclosed in limpid quartz. Fig. 78 represents some of the fossils of this rock. In the absence of the Potsdam sandstone, as at Little Falls, N. Y., it rests upon the pyre-crystalline rocks or the Taconic system. It is more extensive than the former rock. At Chazy, N. Y., it is highly fossiliferous. 124. The Chazy limestone succeeds the calciferous sandstone. It is a dark-colored rock, and abounds in corals. But its most im- portant organic remains are gasteropods, particularly the Macleurea, fig. 79. This name, however, has been changed into Straparollus by D'Orbigny. It was first called Maclurites magnus by Le Seur We have followed D'Orbigny, and hence this remarkable fossil takes the name of Straparollus rnagnus. It is quite common at Chazy and at Essex, N. Y. It is equally common in the same rock in Wythe Co., Va. A coral is also quite common : the Columnaria alveolata, Fig. 80. The Birds' Eye Limestone, which overlies the Chazy, is a close- grained, compact limestone, and breaks with a conchoidal fracture ; it is rarely, if ever, over 30 feet thick. In Canada its color is quite light, and it has been used for lithographic drawings. The fossils of the Trenton appear in the rock. A very singular fossil, called by Mr. Conrad Fucoides demissus, fig. 81, seems to cha- racterize the limestone. Its name has been changed to Phytopsis tubulosum by Hall. Several cephalopods occur in this rock : the most common is the Orthoceras multicameratum, fig. 82. The Bird's Eye is a very compact and brittle rock, and breaks with a conchoidal fracture. It presents numerous crystalline SILURIAN SYSTEM. Fig. 78. 93 1. Scalites angulatus. 2. Straparollus labiatus. 3. Straparollus S triatus. 4. Bellerophoix * satinus. 5. Cast of orthis. 6. Diacina. 94 MANUAL OF GEOLOGY. Fig. 79. Straparollus magnus. Fig. 80. Columnaria alveolata. points, which gives the surface the peculiar appearance from which its name was derived. The Black River limestone, or Isle La Motte marble, is the least com- mon ; but, at Watertown, N. Y., and Isle La Motte, on Lake Charnplain, it is present. It is black, and is ex- tremely fine-grained. It is between seven and fifteen feet thick, and it forms a fine black marble. 125. The Trenton limestone is either black or gray. The lower part is usually black, and when well developed, as at Watertown, N. Y., it becomes gray and sub-crystalline. These divisions of this limestone were made on the ground that each mass contains pe- culiar fossils, and which are confined to each respectively. This is found untrue. The thickness of the Trenton limestone is about 400 feet. The total thickness of the four masses of limestone, as given by Mr. Logan, near Montreal, is 1200 feet, but at the Manitoulin Islands, or westward, they diminish in thickness, and scarcely exceed 300 feet. The Trenton limestone is variable as to its lithological character. At certain localities, as at Chazy and SILURIAN SYSTEM. Fig. 81. 95 Phytopsis tubulosum. Fig. 82. At Orthoceras multicamerata. Montreal, it has intercalated beds of black bituminous slate, other places it is mainly a solid limestone. 126. The fossils are abundant in all these rocks, especially the Trenton limestone. Some of the characteristic forms are repre- sented in the following cuts. Fig. 83. Ventral valve. Fig. 84. Dorsal valve. Strophomena alternistriata. 96 MANUAL OF GEOLOGY. Fig. 85. CEPHALOPODA. Trocholites ammonius. SILURIAN SYSTEM. Fig. 86. CEPHALOPODA. 97 Lituites undatus. Side and Back Views. 98 MANUAJL OP GEOLOGY. Fig. 87. GASTEROPODA. 4. Cyrtolites filosum. 5. Bellerophon punotifronf. Pleurotomaria lenticularis. SILURIAN SYSTEM. 99 Fig. 88. BRACHIOPODA OF THE TRENTON LIMESTONE. ia. Surface of T. terminalis. Leptsena serica Lingula papillosa. Discina truncata. Sections of the Stropliomena. Ambonychia orbicularis. Triple sia exta Strophomena sinuata. Strophoraena alternate. Orthis pectinella. 100 MANUAL OP GEOLOGY. Fig. 89. CRUSTACEA. Triarthrua Beckii. SILURIAN SYSTEM. 101 The Utica slate, which is a black and Fig. 91. tender rock, reposes upon the Trenton lime- FOSSILS OF UTICA stone. It is often bituminous. Its greatest SLATE, thickness is about 75 feet. It does not occur in a condition of a roofing slate. To this slate the Lorrain shales and sandstone suc- ceed. The line of junction is obscure, and the annexed fossils occur in both series of beds. These are thin-bedded shaly deposits with a few calcareous beds interposed. 'The lowest beds are quite thin, and alternate with slate. As we ascend in the series, the sili- cious or sandy beds become thicker, and the L Triarthms Becwi. formation finally terminates in a thick-bedded gray sandstone in New York and Canada. In the West, or in the vicinity of Cincin- nati, the whole formation is much more cal- careous, and is there known as the Blue Limestone. It is fossiliferous, especially in the West. 127. If we now turn our attention to the south-west, or Wytheville, and the head waters of the Clinch and Holstein, Virginia, we find these masses to wear a different phase from what they do in New York and Canada. Thus, the Potsdam sandstone has an open texture, and alternates twice with the Calci- ferous sandstone ; the latter, in many places, consists almost entirely of chert. The Trenton limestone is white and crystalline, though loaded with organic remains, and is entirely destitute of bitumen. The Lorrain shales and sandstones, in the ascending order, consist of, first, a reddish, mottled sandstone, pebbly at bottom, but becomes a sandy marl, and contains fossili- ferous bands, which serve to identify it with the rock in Northern New York. It is about 100 feet thick. Above this mass there is a calcareous shale, which finally becomes a thin-bedded lime- stone, and, still higher, there are olive-green, thin-bedded sand- stones and marls, containing Pterinea carinata. These beds are equivalent to the thick-bedded sandstones of Oneida, Jefferson 9* 102 MANUAL OP GEOLOGY. Fig. 92. FOSSILS OF THE LORRAIN SHALES. 1. Murchisonia gracilis. 2. Avicula demissa. 3. Orthis testudinaria. 4. Modiolopsis roodiolaris. 5. Orthis crispata. 6. Pedicloof cystidean. 7. Heterocrinus. 8. Porcelia ornata. SILURIAN SYSTEM. 103 county, New York, and the Blue limestone in part of the Western States. 128. Oneida Conglomerate. Above, and resting upon the last member of the foregoing series, is the Oneida conglomerate, or Sha- wangunk grits. It is a hard gray rock made principally of pebbles. Whether it should be considered as holding a connection with the foregoing rocks, or be regarded as the inferior member of the Middle Silurian, is not well determined. In one point of view, it is an important rock, insomuch as it indicates a line of demarkation between the Lower and Middle Silurian rocks. It is probable, that it belongs to the Middle Silurian. Fig. 93. Trinucleus Caractaci? Conularia Hudsonia. Enlarged. Receptaculites belongs to the sub-class Bryozoa, and appears to be a rare fossil. The Conularia belongs to the class Pteropoda, and is also a rare species in the Lorrain shales. The Lower Silurian, in Northern New York, is rarely disturbed by dykes or intruded rocks. In Jefferson and St. Lawrence coun- ties, the Potsdam Sandstone is tilted up, and the specular oxide of iron, in those cases, often occupies a position between the Potsdam and the primary rocks beneath. On the Champlain side near the village of Essex, and, indeed, in many other places, trap-dykes and porphyritic rocks cut through the lower limestones. Near Essex, the Calciferous sandstone is raised upward, so as to 104 MANUAL OP GEOLOGY. Fig. 94. b a ft Disturbed Strata in the Lower Silurian, Essex Co., N. Y. be on a level with the Utica slate, as represented in Fig. 94. a, calciferous sandstone; J, line of junction with the slate; c, thin dykes traversing the slate ; b, slate thrown into undulations. The foregoing represents a series of phenomena which are common in districts disturbed by faults and igneous injections. 129. Middle Series of the Silurian or Ontario Division of the System. It comprehends the Oneida Conglomerate or Shawan- gunk Grits, the Medina Sandstone. Clinton, and Niagara Groups. In the West, this division is called Cliff Limestone, not including the Oneida Conglomerate and Medina Sandstone. The Medina Sandstone is an argillaceous mottled sandstone, in part, and is easily destructible by atmospheric agencies ; hence, it rarely appears in sharp well-defined outcrops. The upper part consists of firm and thin beds of light-reddish sandstone, with a texture sufficiently close to preserve, in perfection, ripple marks and wave lines. There is also a coarse gray band at the top in the gorges of the Genesee river, which is somewhat pebbly. The rock is also mottled with light-green patches like the New Red or Triassic Sandstone. It is the lowest rock which is known to furnish brine-springs. They are not, however, pure enough, nor do they furnish saline matter in sufficient abundance, to be em- ployed economically in the manufacture of salt. It forms a border along the shore of Lake Ontario and the crests of the Alleghenies in Virginia. Fossils of the Medina Sandstone : The most common fossil is the Arthopycus Harlani, fig. 95, a marine vegetable, and formerly described as the Fucoides Harlani. It is common to New York and the Virginia series. The Lingula cuneata (Fig. 96) is also a common fossil. 130. Clinton Group. It consists of many beds comprising gray and brown sandstones, green shale, slate, conglomerates, limestones, SILURIAN SYSTEM. 105 Fig. 95. J Arthopycus harlani. 106 MANUAL OF GEOLOGY, Fig. 96. Lingula cuneata. and oolitic iron ore. It has been called the Protean Group on account of the heterogeneous assemblage of materials. In Warren, Herkimer County, New York, the following section occurs : 1. Bluish Gritty Shale, 1 foot. 2. Gray Sandstone, 2 feet. 3. Blue Gritty Shale, 1 foot. 4. Gray Sandstone, 4 feet. 5. Pebbly Beds, 2 feet. 6. Blue Shale, i foot. 7. Grayish Shale, i foot. 8. Iron Gray Sandstone, foot. 9. Thin-bedded Sa-ndstone, 1 foot. 10. Fine Pebbly Conglomerates, 8 feet. 11. Soft Brown Sandstone, 2 feet. 12. Dark-colored Shale, 3 feet. In the debris are fragments of iron ore. The bed is concealed. This series rests on the Oneida Conglomerate, as the Medina sandstone does not extend so far east. On Steel's Creek, at Mohawk, the formation attains its maximum thickness, which is about 70 feet. At the West, the formation presents a different aspect. At the Lower Falls of the Genesee, reckoning in the ascending order, we have obtained the following section : 1. Gray Band of the Medina Sandstone. 2. A Tender Fissile Green Slate. 15 feet. 3. Lower Bed of Oolitic Iron Ore. 14 inches. 4. Limestone with Pen- tamerus oblongus. 14 feet. 5. Green Shale, like No. 2. 24 feet. 6. Impure Limestone and Shale. 18 feet. To the east, this group is sandy, or made up of grits, while to the west it becomes calcareous. At Anticosti, the Clinton group is well-developed, or the rocks consist in part of this group. Walker's Mt., on the head waters of the Clinch River, in South- Western Virginia, and the subordinate ranges of this region, are composed of the rocks of this group. The Medina sandstone often forms their summits. SILURIAN SYSTEM. Fig. 97. FOSSILS OF THE CLI-NTON GROUP. 107 1. Rusophycus bilobatus. 2. Hemicripturus. 3. Crinoidal Joint. 4. Lingula oblonga. 5. Strophomena depressa. Pentamera3 nobilis, E. 108 MANUAL OP GEOLOGY. Fig. 98. 1. Atrypa imbricata. S5. Atrypa. 3, 4, 4a. n ynconella cuneata. 6. Euomphalus hemisph ricus. 8. Illsenus barriensis. SILURIAN SYSTEM. 109 Fig. 99. BRACHIOPODA OF THE NIAGARA GROUP. 1. Spirifer Niagarensis. 2. Spirifer radiatus. 3. Spirifer staminea. 4. Spirifer decemplicatui. 5. Orthis flabellum. 6. Orthis canalis. 7. Orthis hybrida. 8. Spirifer finuatus. 10 110 MANUAL OP GEOLOGY. Fig. 100. CRINOIDS OF THE NIAGARA GROUP. Ichthyocriuus laevfo. lyecanocrinus macropetalua. SILURIAN SYSTEM. Ill Fig. 101. CORALS OF THE NIAGARA GROUP. 1, 2, 3. Halycites catenularia. The Halycites (Catenipora) catenularia is probably never found above or below the Clinton and Niagara groups, and is hence a very characteristic fossil. 112 MANUAL OF GEOLOGY. Niagara Group. It consists mainly of three members : Nia- gara shale, Niagara limestone, and Coralline limestone. The first is a tender, bluish rock, which whitens on exposure to the weather. The second is often a dark-colored massive limestone, and frequently bituminous. It may be described in the following section : 1. Beds of gray silicious limestone, often hydraulic. 2. Thin beds of shaly limestone, sometimes concretionary. 3. Thick and thin beds of limestone. 4. A cherty and bituminous limestone; gray or brown, -with numerous geodes of calcspar, gypsum, strontian, or brown spar. The limestone is often crystalline and sparkling, as at Lockport. The eastern limit of this limestone is Swift Creek in Oneida Co., where it is curiously concretionary, and only about four feet thick. Thickness of the Ontario Division in New York. The Medina Sandstone is 350 feet tnick. Clinton Group 80 " Niagara Shale . . . . . . .100 " Niagara Limestone . . . . . .160 " 131. The Coralline Limestone, in the Helderberg, rests on green shale, which is, no doubt, the representative of the Clinton group. It is scarcely probable the equivalent of the Niagara limestone, as the rock contains fossils similar to those which cha- racterize the succeeding masses. 132. General Distribution. The Ontario division is quite ex- tensive in the United States. In New York it forms a narrow belt along the south shore of Lake Ontario. It dips south or south-west. In Pennsylvania it occupies a narrow belt along the north-western base of the Kittatinny Mountain. It extends from Perry county, nearly to the Delaware Water Gap. The Medina sandstone, accompanied by the Clinton group, with its iron ores, form the summits or belts of all the ridges west-south-west of Wytheville, Virginia. The top of Walker's Mountain, about twelve miles from Wytheville, is probably carboniferous ; but, immediately beneath, the Medina sandstone, becomes a very prominent rock, and caps the ridge on Shannon's side of this mountain. In a descend- ing order, we find the following succession : SILURIAN SYSTEM. 113 1. Clinton group, and an imperfectly developed Niagara limestone, which is very cherty. 2. Medina sandstone. 3. Upper Lorrain shalo, slates, and sand- stones. 4. Calcareous beds. 5. Lower Lorrain beds, consisting of green shale, brick red massive slates, and very tough; gray sandstones and conglomerate. 6. White Trenton limestone. 7. Bird's Eye and Chazy limestone. 8. Calciferous sandstone with drab-colored layers. 9. Gray sandstone (Potsdam). This divi- sion of the Silurian occupies, therefore, the summits or ridges of the high ranges about the head waters of the Clinch and Holstein. 133. Helderlerg, or Upper Division of the Silurian System. In this series we place the Onondaga salt and plaster group. The Manlius Water limestone, Pentamerus limestone, green shaly limestone, Encrinal limestone, and Upper Pentamerus limestone. 134. The Onondaga Salt Group consists of soft, red, and mottled argillaceous shales, which, at many places, pass into a drab color. The lower part is a bluish marl, with bands of red and brown ; above, it becomes calcareous, and contains seams of gypsum, and at its termination in Onondaga Co., it becomes gray or drab-colored lime- stone, which is magnesian. The contrast between this great deposit of soft shales and marls is very great, when compared with the Niagara limestone on which it rests. The softer portions contain hopper form cavities, or moulds which appear to have contained crystallized rock salt. 135. Extent. Westward it extends into Canada : an obscure mass of rock, about 20 feet thick, in the Helderberg and at Schoharie, represent the whole formation. It is not generally dis- tributed, and should be regarded rather as a local, though by no means an unimportant formation. It furnishes from its middle beds a large quantity of plaster, and from the wells, which are usually sunk in drift, brine springs, which give a large revenue to the state of New York. Fig. 102. WATER LIME FOSSILS. 1. Spirifer plicatus. 2. Avicula mgosa. 3. Tentaculites omatns. 4. Holopea antiqua. 5. Atrypa lulcata. 6. Leperditia alta. 114 MANUAL OF GEOLOGY. 136. Water Lime, or Manlius Water Lime Group. It consists of thin-bedded drab, or gray limestones. The upper beds are thick, and are employed for the cement so well known in market. The Pentamerus limestone succeeds, and it is almost always con- cretionary, at least in part. It is gray and thick-bedded. Both the foregoing masses are well developed at the base of the Helderberg, and also in the valley of the Rondout, and Becraft's Mountain, east of Hudson. Green shaly limestone is an argillaceous limestone, and many of its layers are very thin : rarely crystalline. It weathers from a bluish color to a drab. It may be examined at Becraft's Mountain, and on a line of outcrop from Kingston Point to Coeymans at the Helderberg, Schoharie, and west a short distance beyond Cherry Valley in New York. It is about thirty feet thick. It is remark- ably rich in fossils, but is not widely distributed. 137. Encrinal Limestone. It is a semi-crystalline rock, and is made up in great measure of peculiar crinoidal remains. It is nearly a pure limestone, and polishes well, and hence it often furnishes fine slabs for mantel-pieces, tables, &c. It is 25 feet thick at Becraft's Mountain, and but scarcely exceeds 10 at New Scotland in the Helderberg. Fig. 103. BRACHIOPODA OF THE UPPER SILURIAN. Rhyconella formosa. a, 6. Dorsal view. c. Ventral view, d, e. Edge view SILURIAN SYSTEM. ' Fig. 104. BRACHIOPODA OP THE UPPER SILURIAN. 115 1, 2. Strophomena Woolworthanau Strophonfeaa Headlcyana. 116 MANUAL OP GEOLOGY. Fig. 105. BRACHIOPODA OF THE GREEN SHALY LIMESTONE. Side view. Trent view. 1, 2, 3, 4. Merista arcuata. 4, 5, 6, 7, 8, 9. Merista Isevis. 10, 11. Merista princepf. SILURIAN SYSTEM. Fig. 106. BRACHIOPODA OF THE UPPER SILURIAN. 117 1, 2, 3, 4. Meristabella. 5. Merista princeps. 6, 6 a, 6 b. Rhynconella mutabilis. . 7. Orthis. 8, 9, Rhynconella mutabilis. 9 a. Rhyncoaella ventricosa. The genus Merista is closely allied to the Terebratula : its beak is imperforate. Their shells are ovate, sometimes transversely so, and are ornamented by parallel circular lines. The mesial fold is much less prominent than in the Rhynconella. The shell is thin, often ventricose. The beak is rather prominent and incurved. 118 MANUAL OF GEOLOGY. Fig. 107. BRACHIOPODA OF THE UPPER SILURIAN. 2 1, 2, 3, 4, 5, 6, 7. Etonia medialis. 8. 9. Rhynconella transversa. 10. Rhynconella aoutiplicata. 11, 12, 13, 14. Rhyneonella altiplioata. The Etonia medialis was formerly the Atrypa medialis of Van- uxem, figured in the New York Geological Reports. The internal structure of the fossil is found to differ from the genus Atrypa ; and hence the necessity of changing the name of the fossil. The ventral valve is also flat, and the hinge is indicated by a straight line. SILURIAN SYSTEM. Fig. 108. BKACHIOPODA OF THE UPPER SILURIAN. 119 1. Rhynconella abrupta. 2, 3. Bhyncouella vellicata. 4 Pentamerua galeatus. 5. Pentamerua Vernuijli. The Rhynconella is marked externally by a strong mesial fold, and the shell is ribbed and often highly ornamented by numerous pli- cations of the ribs. The sinus is often deep ; and one valve appears always to extend itself around the base and to interlock upon the opposite side. They appear to be closely united both to the Terebratula and the Atrypa. The Pentamerus galeatus (fig. 4), is the characteristic fossil of the lower Pentamerus limestone. 120 MANUAL OF GEOLOGY. Fig. 109. BRACHIOPODA OF THE UPPER SILURIAN. 1, I a, 1 b, 1 c. Rhynconella mutabilis. 2. Rhynconella semiplicata. 3. Rensselaeria sequicoa- tata. 4, 4 a. Rhynconella nobilis. 4, 4 a, 4 b, Rhynconella nobilis. SILURIAN SYSTEM. Fig. 110. 121 Platyceras plicatum. 1. Anterior side. 2. Left side. 3. Posterior side. 4. Folds of the anterior side. 11 122 MANUAL OF GEOLOGY. Fig. 111. CRUSTACEANS OF THE GKEEN SHALT LIMESTONE. 1 a. Lychas, and 1 b, (undescribed.) 2 a. Acidaspia. 2 b, and 2 d. Shield showing the spines. 2e. Spine of the buckler enlarged. 2/. A single rib. 2 h. Pygidium. 3 6. 4. Eurypterus remipes of the water lime group, (young.) SILURIAN SYSTEM. 123 At certain places, as at Becraft's Mountain, and at Schoharie, a gray limestone succeeds which is full of a peculiar species of pen- tamerus. It is only a few feet thick. According to the present views of geologists, this last mass is the last also of the Silurian System. It may, therefore, be seen that the upper part consists of a series of pure and impure limestones. It will be evident, too, that the threefold division of this system is convenient, and aids the memory of the student. The greenish shaly limestone of the Helderberg range of New York is probably one of the richest rocks in fossils of the Upper Silurian System : and yet this rock seems to be quite limited in extent. It ranges west to Cooperstown, becoming gradually thinner ; it however carries its fossils to its western limit. It is well devel- oped in the Becraft Mountain, three miles east of Hudson and west of Catskill, N. Y. The bed containing the Lychas is quite limited; the species itself is closely allied to the Lychas boltoni of the Niagara group. The Acidaspis is also quite rare, and limited to a thin stratum of rock in the green shales of the Upper Silurian. The spines of this genus furnish a clue to its recognition. The Eurypterus remipes is the characteristic crustacean of the water lime. It is furnished with eight tentacular organs, four being placed on each side of the head. Its organs of locomotion were similar to oars, rather than feet. The tail is attenuate and sharp- pointed. Under the name and form of Cliff limestone, which is both sili- cious and inagnesian, this group is widely extended in Indiana, Ohio, Illinois, and Wisconsin; and is 7 to 800 feet thick. This lime- stone supports a coralline and shelly limestone which is represented in New York by the Onondaga and corniferous limestones of the Devonian system. It will, therefore, be observed that several rocks which are important eastward are absent in the west: viz., the whole of the Onondaga salt group, the water limes, Pentamerus limestone, Delthyris or green shaly limestone, Encrinal limestone, and Upper Pentamerus limestone. The student will understand from the foregoing facts that the Silurian is more complete in New York than in the Western States. The lower mass of the Cliff limestone represents the Upper Silurian, and yet there is a mixture of Upper and Lower Silurian fossils, as the Illsenus crassicauda, Leptaena alternata, and Phacops caudatus. 124 MANUAL OF GEOLOGY. Table showing the equivalency of the New York members of the Upper Silurian with those at a distance. New York. Onondaga salt group. Niagara limestone. Coralline limestone. Niagara shale. Clinton group. Western States. Inferior part of the Cliff limestone of the Ohio geologists equivalent to Upper Silurian. Niagara and' Clinton 1 groups in part, con- taining Pentamerus oblongus and Pha- cops caudatus. England. Wenlock limestone and shales and Gothland. Stage above the Cara- doc sandstone. In England the stage represented here by the Clinton group being intermediate between the Wenlock and Caradoc, is not repre- sented there by any yet described series ; unless by Sedgwick, who places the Mayhill sandstone and Woolhope limestone in a position parallel with our Clinton group. The Silurian System occupies large areas in the northern, western, and southern parts of the United States. The Lower Silurian skirts the eastern shore of Lake Champlain, and exists in detached and isolated outliers in the Hudson River Valley; and small patches of the calciferous sandstone occur as far east as Hoosic, Rensselaer Co., N. Y. West of Champlain it extends west as far as the parallel of longitude of 97, and as far south as Tuscaloosa in Alabama. Its westward and southward extent therefore is about 1500 miles. At these extreme southern and western limits the system disappears under the cretaceous and tertiary rocks. On the north-western, eastern, and south-eastern borders it rests unconform- ably upon the Taconic System. Fig. 112. Eyes of Trilobites, showing that the eyes of insects of the present day are constructed on the same plan. 3. Enlarged lens. CHAPTER XIII. DEVONIAN SYSTEM. 138. THIS system, though much thicker than the Silurian, is geo- graphically less extended in this country. Like the Silurian, it is one of the general systems, and is found, it is believed, in all the great natural divisions of the earth's surface. All such systems indicate certain uniformities in the operations of nature, as well as simultaneous movements which produced ana- logous results in the 1 same epochs in the history of the earth. In no epoch, however, do we find perfect uniformity in the quantity of sediment by which the length of this epoch is measured. Re- markable differences are found when the eastern and western series constituting this system are examined. Certain subordinate groups of the system are wanting, and in others the system does not exist at all, and the Carboniferous, the next system above, lies directly upon one of the members of the Silurian. Thus, in Kentucky one member of the Devonian only exists : the Genesee slate is the only rock separating the Carboniferous from the Silurian. In Ohio the members of the Devonian, which intervene between the Carboniferous and the Silurian, are parts of the Chemung group. They are called Olive sandstones, the Genesee slate, Niagara group or part of the Cliff limestone. In New York this system is very thick, and is divisible into many groups; but westward and south-westward it constantly diminishes in thickness, and ultimately disappears. In England and Scotland the Devonian holds an important place. It was the field of Hugh Miller's most valuable and popular labors. In England the thickness of the Devonian is eight thousand feet. Mr. Lyell states that on the coast of Rosshire the old red sand- stone forms isolated hills resting on gneiss ; the strata are horizon- tal, and only three thousand feet thick in consequence of denudation. In this region it is evident from the diminished thickness and the 11 * (125) 126 MANUAL OP GEOLOGY. insulation of the hills, that forces or agents have worn off, and cut down these strata to the very base on which they rest. But the most interesting fact to us is the co-ordination of these distant beds with our own, being shown by the similarity of fossils, or the close affinity of fossils which identifies this distant formation with our own. Thus the remarkable fish, the Holoptichius nobi- lissimus, is common to both countries ; the asterolepis, upon which Hugh Miller bases his celebrated argument against the transmuta- tion theory, is also common to both countries. This system in New York is composed of the following rocks and groups of rocks. Oriskany sandstone, two to three feet thick, but between 600 and 700 feet in Pennsylvania ; Cauda galli grit and Schoharie grit, seven to ten feet thick ; Onondaga limestone and corniferous limestone, 120 feet thick; they really form but one rock. Marcellus shale, Hamilton group, Tully limestone, only 14 feet thick ; Genessee slate, Chemung group, and Cattskill group. According to M. De Yerneuil, the lowest rock of this system in New York is the Oriskany sandstone. If we take the Helderberg and Cattskill Mountain group as the type of the system, we shall find two zones of shales and sandy beds; one below and one above, with a heavy limestone formation between. The sand- stones and sandy beds embrace the Oriskany sandstone, the cauda galli grit, a dark drab-colored silicious shale, above which there is another grit only seven or eight feet thick, called the Schoharie grit ; it is important only as the repository of many fossils. Upon these repose the Onondaga and corniferous limestones. . The latter passes into shales, which are soft, dark-colored or black, and in some parts quite calcareous. They contain many peculiar fossils, and they have become generally known as Marcellus shales. The Hamilton group, which succeeds, consists of shales and silicious beds and sandstones, which are generally thin-bedded and dark-colored, but weather to a brown. Among the shales there are impure calcareous bands, and calcareous matter is disseminated to a small extent through different bands of the formation : these are the best repositories for fossils. The Tully limestone succeeds the Hamilton group;, it is only 14 feet thick. Upon this limestone the Genesee slate reposes ; it is thin-bedded, black, and calcareous. DEVONIAN SYSTEM. 127 Fig. 113. RHYNCONELLA BARRANDI. 1. Side view, showing its ridges. 2. Back view.-It is believed to be confined to the Oriskany sandstone the lowest member of the Devonian System. The RhynconellaBarrandi is rather common at Cumberland, Md. It is one of the largest of this genus. MANUAL OF GEOLOGY. Fig. 114. SPIRIFER ARENOSUS. 1. Spirifer arenosus. 2. Rensselaeria ovoides. 3. Etonia peculiaris. The Spirifer arenosus is the most common fossil of the Oriskany sandstone. It often occurs in casts. See 111. 5. DEVONIAN SYSTEM. 129 Fig. 115. 4. Orthis unguiformis. 5. Cast of the Spirifer arenosm. The Oriskany sandstone, though thin in New York, contains pro- bably all the fossils which strictly belong to the rock. It is often a mass of shells or the cast of shells. 130 MANUAL OF GEOLOGY. Fig. 116. u P. Sagittatus. Enlarged. 1, 1 a, 1 1>. I e. Atrypa impressa. 2. Pentamerus aratus. 2 a. Side view. 3. Plearor) r.cw The mass to which the foregoing fossils belong is crowded with them, but they are frequently in the condition of casts. DEVONIAN SYSTEM. 131 The Portage and Chemung groups succeed. They are partly shales passing into flagging-stone and rarely into thick-bedded sand- stone. They are followed by the Cattskill group, which consists of dark-colored shales which frequently alternate with red shales and sandstones. It has been regarded as the equivalent of the old red sandstone of England and Scotland. It forms the greater portion of the Cattskill Mountains. Conglomerates occur at the top of the Cattskill rocks belonging probably to the carboniferous system. The Devonian System does not exist east of the Hudson River. West of the Mississippi the Devonian is represented by either the Portage or part of the Chemung group. The fossils of the Devonian are exceedingly numerous, and differ remarkably from those in the Silurian. Its most interesting fossils are fish, among which the ganoids are conspicuous. In this system reptiles begin their career, but they are feebly represented, and only foreshadow the future of this important class. In Europe only two reptiles have as yet been discovered ; the Telerpeton of Mantell, and the Staganolepis ; the former is supposed to belong to the Batrachian family ; the latter has a close resemblance to the Teleo- saurus. Plants which bear a resemblance to coal plants, and are undoubtedly of terrestrial origin, begin to appear in the upper part of the system. Corals and mollusca abound throughout. The foregoing groups collectively compose the Devonian System. The rocks from the Genesee slate to the conglomerate at the top of the Cattskill, constitute really but one series, though for con- venience it has been subdivided into groups. The deepest part of the Devonian sea appears to have been in the region of the Catts- kill series. The prolongation of the Devonian and Silurian east- ward is quite limited. There is no Devonian on the east side of the Hudson River. The Upper Silurian is prolonged four or five miles eastward of the city of Hudson, and forms the upper part of Be- craft's Mountain, where it suddenly disappears towards the east. 139. The valuable products of the Silurian and Devonian of this section are limestones for marble and for quicklime ; the flag-stones belong exclusively to the Devonian. No ores or coal belong to either system in this part of the state. There are no limestones proper above the Tully limestone. The Devonian in Ohio is much thinner than in New York. Its members are called, 1st. Olive-colored sandstone, which are equi- valent to the Chemung group in New York ; the Marcellus shales, 132 MANUAL OF GEOLOGY. 100 feet thick, and the Cliff limestone, the upper part of which, is equivalent to the corniferous limestone which reposes directly upon and is conformable to the blue limestone in part of the west, and which is the equivalent of the Lorraine shales. In the South-west, in the county of Wythe, the Devonian is not recognisable, the car- boniferous resting directly upon the Upper Silurian, or the Clinton and Niagara groups : this is the case in certain places, and if the Devonian exists at all, it is in exceedingly thin masses, and will be found the equivalent of the New York Chemung group. Fig. 117. FOSSILS OP THE MIDDLE DEVONIAN SYSTEM, OR HELDERBERG LIMESTONE. 7 1, 2, 3. Orthis subcarinata. 4. Orthis oblata. 4 o. Orthis perelegana. 5. Spirlfcr. 6, Chonatei iMunUphericus of the Schoharie grit. 7. Strophomena. DEVONIAN SYSTEM. 133 Fig. 118. 1. Dalmania selennrus. 2. Cyrtoceras undnlatus. 3. Chonctes lineata. 4. Orthis lenticular!* & Atrypa reticularis. 6. Transverse section of an Ichthyodolerite. 12 134 MANUAL OF GEOLOGY. Fig. 119. 1. Rensselaeria (Meganteris) elongata (Hall). 2. Atrypa reticularis. 3. Spirifor undulatua. DEVONIAN SYSTEM. 135 Fig. 120. 1. Cyrtoceras. Back view, showing the undulating , septse. 2. Ichthyodolerite of the Onondaga Limestone. 136 MANUAL OF GEOLOGY. Fig. 121. 1. 2, 3, 4, 5. Strophomena Patersoni. 2. Hinge view and muscular impression. 3. Edge view. 6. Stropho- mena inoquistriata. 7. Strophomena crenistriata. DEVONIAN SYSTEM. MAKCELLUS SHALES. Fig. 122. Fig. 123. 1, 2. Goniatites. 3. Orthis limitaris. 4 Cypricardia marcellanus. Bellerophon patulus. 2. Microdon bellastriatM. 12* 138 MANUAL OF GEOLOGY. Fig. 124. HAMILTON GROUP. 2. Atrypa gpinosa. 3. Nucleospira concinna. 4. Strophomena inequistriata Con. 5. Spirifer zig- zag (Hall). 6. Phacops bufo. 6. Dalmania callitcles. 8. Loxonema nexilis. Fig. 125. 1. Fleurotomaria lineata. 2, 3, 3. Spirifer mncronatns. 4. Atrypa priaca. DEVONIAN SYSTEM. 139 Fig. 126. 1 Orfchoceras constrictura. 2. Cypricardites reeurva. 3. Avicula flabella. 4. Discina grandia. 140 MANUAL OP GEOLOGY. Fig. 127. 2. Spirifer medialis. 3. Spirifer an . 4. Cyrtia Hamiltoniensis. Fig. 128. 1, 2, 3, 4, 5. Orthis Vanuxemi. 1 e. Hinge view. 1 4. View of the Ventral Valve, a, 6, c. Orthis umbonatut. DEVONIAN SYSTEM. 141 Fig. 129. 2,26.Tropidolepu 8 carmato8. 1, 2. Strophomena demissa. 1 a. Muscular impression. 2 a. Young. 142 MANUAL OP GEOLOGY. Fig. 130. DEVONIAN SYSTEM. 143 Fig. 131. Bpirifer Maroyi. Sa, 4a. Hinge view. 144 MANUAL OF GEOLOGY. Fig. 132. MO. Cypricardites (Gramysia) Hamiltoniensis. 2. Orthonota undulata. Cypricardites, or Gramysia of De Vernueil, is one of the cha- racteristic fossils of the shales and sandstones of this group. The Orthonota is by no means an uncommon fossil in the same series. The Helderberg Mountains, Albany, Co., N. Y., and the ranges of mountains in Schoharie County, are also depositories for the fossils of this group. DEVONIAN SYSTEM. Fig. 133. CORALS OF THE DEVONIAN SYSTEM. 145 1. Heliophyllum Halli. 2. Eridophyllum simconensis. 3. Favosites gothlandica. 4. Syringopon. elegans. 5. Aulopora cornutum. 6. Phillipsastrea yerncnili. 7. Zaphrentia prolifera. 13 146 MANUAL OF GEOLOGY. Fig. 134. nom]nm.t".F Dokavi. Side. DEVONIAN SYSTEM. Fig. 135. 147 Homalonottis Dokayi. Back view. 148 MANUAL OF GEOLOGY. GENBSEE SLATE. Fig. 136. 2, 2. Avicula fragilis. 3. Chonetes setigera. 4. Tentaculites fissurella. i Fig. 137. Diacina lodensis. 2. Rhynconella qoadrieoetata. 3. Lingula spatulata. 4. Lingula concentric*. The Genesee slate is a black fissile rock, and rather poor in fos- sils. The fossils, too, are small and obscure in the state of New York. DEVONIAN SYSTEM. 149 Fig. 138. CHEMUNG GROUP. 1, 2, 2 a. Bellerophon cyclopetrus. 1. View of the top. 2 a. Side view. 2. Phaoops nupera of the Chemung Group. 13* 150 MANUAL OF GEOLOGY Fig. 139. CHEMUNQ GROUP. , 2, 3. Produotus hirautus. 4. Productus rarispinis. 5, 5, 6. Produotua Bojdii. 7. Young o< ftirstitus. DEVONIAN SYSTEM. Fig. HO. CATSKILL GROUP, OR OLD RED SANDSTONE. 151 2. Jaw of Holoptichius Taylori Terabratula lepida. 152 MANUAL OF GEOLOGY. Fig. 141. Lepidodendron ? Devonian Plant. CHAPTER XIV. CARBONIFEROUS SYSTEM AN IMPORTANT EPOCH A STAND- POINT FOR RECKONING GEOLOGIC TIME, VEGETATION, COAL, AND PROSPECTIVE MATERIAL DESIGNED FOR THE USE OF MAN FORMATION ILLUSTRATED VEGETABLE FOSSILS DIVI- SION OF THE SYSTEM INTO LOWER CARBONIFEROUS, AND THE COAL MEASURES, ETC. RECAPITULATION. 140. THIS system fills the most important epoch in the earth's history. Unlike the Devonian and Silurian, it abounds in useful products, and these products, taken collectively, have been the most direct and efficient agents in promoting that high degree of civilization which now prevails. Of these valuable products, coal is the most essential material, and from its abundance in this sys- tem it has derived its distinctive name, the Carboniferous System. To the geologist it is often a point of departure for his reckoning of geologic time, or it may be employed for determining his true position in the geologic scale, as it occupies a mid position ; and hence the past and future are necessarily in certain determinable relations which may be viewed with great advantages from this stand-point. Of all the systems, too, it is more constant and uniform in its characteristics, when continents or large areas are compared, than those which succeed it. This statement applies both to its fossil remains and its mineral constitution. 141. It was in this epoch that the earth began to wear a fairer and more promising aspect. It was clothed with a vegetation which would bp prized by civilized man. It was a period when forests of coniferous trees adorned the land ; and if compared with the Devo- nian, it would present a striking contrast, as the latter has pre- served no trees or forests, and hence it is probable would appear as an arid or barren waste. Previous to this time we have only feeble indications that the earth was watered, as it is now, by showers of rain. (153) 154 MANUAL OF GEOLOGY. In the carboniferous series, however, there were soils which bore land plants, and trees of a large growth ; as we now find their remains in an erect position with their roots still fixed in the earth in which they grew. So also the sandstones and shales contain prostrate trunks, denuded of limbs and bark, which must have drifted down rivers and finally into the ocean, where, becoming water-logged, they sank, and were buried under mud and sand. The vegetable kingdom, then, as it is represented in these relics, furnishes unmistakable evidence of progress. Besides, we look back to this epoch with great interest for its prospective products, its coal especially, which we believe we are warranted in regarding as a special provision for man. We can view in no other light these great deposits of fuel, which required ages for its growth and sub- sequent consolidation to fit it perfectly for the parlor, the workshop, and steam-engine. 142. It is proved by direct observation, that coal is of vegetable origin. By the aid of the microscope, it is found composed of the vegetable tissues ; almost every particle has preserved in its sub- stance ducts or vessels, organs of growth which are peculiar to the vegetable kingdom ; hence, although it is enclosed in beds of rock, it has an origin out of the pale of the mineral kingdom. To illustrate the circumstances and the succession of events which were connected with each other in the production of coal and the formation of the accompanying beds, we may refer to peat, a substance which we know has a vegetable origin. In the first place, peat is formed only in cool wet places. If the temperature is much above 75 or 80, the vegetable matter is consumed ; for example, in the eastern counties of North Carolina peat is formed, while in the middle counties, though the surface is protected by forests, it is not found, neither is there a trace of bin 1: vegetable mould. Though there is an annual addition of vegetabt'- substance to the surface ; it is all consumed. But the low grounds of the eastern counties being wet and swampy, the temperature never reaches that point at which a slow combustion takes place, as is the case in the middle counties. So also we infer that coal plants grew only in grounds which were wet and cool, though the temperature of the uplands may have been comparatively high as at the present time. It is agreeable then with what we know of the conditions required to preserve vegetable matter, CARBONIFEROUS SYSTEM. 155 and convert it into coal, that a low temperature must have prevailed over those areas. 143. Peat occurs only in single beds; but in the coal measures numerous beds of coal occur one above the other, which are sepa- rated by a variety of mineral products. Here then the similarity in the circumstances attending the production of peat and coal ceases. It becomes necessary to explain how several beds may have been formed in succession and over the same area, for it is plain that each bed was formed at the surface and bounded by the air above, and by the wet soil below ' } and that each coal area, as in the case of peat, must have been covered with growing vegetables while the surface was virtually stationary. To account for the occurrence of successive beds of coal, it is supposed 'that after a stratum of vegetable matter had been accu- mulated, a subsidence took place by which the surface was sub- merged beneath the water, and that sand, clay and pebbles, materials derived from neighboring hills, or from distant parts, which would be brought down by rivulets and streams, would in time form a sufficient accumulation of debris to fill up the basin or estuary ; thus forming a swamp or morass upon which a new vegetation would spring up and furnish new matter for. another bed of coal. We may consider then that repeated subsidences must have taken place after intervals of rest, and it was during those intervals of rest that beds of sandstone, shale, underclays, &c., were deposited. This figure includes the following beds as occurring in the Nova Scotia coal measures. 1. Shale and sandstone. 2. Slate and sandstone with erect calamites. 3. Gray sandstone 7 feet. 4. Gray shale 4 feet, with an erect coniferous tree. 5. Sandstone 4 feet. 6. Gray slate 6 inches, with erect and prostrate trees, rootlets, leaves, and a inodiola. 7. Main coal measures 3 feet 6 inches. 8. Underclay with roots. Fig. 142. 156 MANUAL OF GEOLOGY. Fig. 143. Calamites with Leaves and Roots. 144. But there were many stationary periods which are not indicated by a coal seam ; for at unequal intervals areas occur which were covered with a close vegetation embracing trees of a large size. The proof rests on the facts that underclays, soft sandstones, and shales are penetrated by roots, and frequently upon what were once their upper surfaces, stumps and trunks of trees are still standing in situ, fig. 142. All such areas mark a stationary period. The most common roots are those of the Sigillaria and Lepido- dendra; the former had a fluted trunk, the latter was singularly marked with rhombic scars of leaves. The roots of the former, however, are known as stigmaria. They frequently have the strong fibre of the main stem of the root still attached. Another vege- table which seems always to have grown in company with the pre- ceding is the Calamites, fig. 143, with its fluted and jointed stems. CARBONIFEROUS SYSTEM. 157 These formed jungles similar to the cane brakes of the Southern States. Fig. 143 shows the verticillate leaves which issue from the joints. The stem terminates below in an obtuse point. 145. The Carboniferous System is divided into two parts, a lower and an upper. The lower is composed lithologically of the Carboniferous limestone. The upper, or coal measures proper, are made up of micaceous sandstones, conglomerates, underclays with superincumbent coal seams, brown, gray, and bituminous shales with clay ironstones. The former belongs to a deep sea deposit, and is filled with marine molluscs, crinoids, and vertebrates, which are mostly fish. It is not always present ; it is absent in the Penn- sylvania coal fields, but present in those of the Western States. The latter belongs to a shallow sea or to estuaries formed in the imme- diate vicinity of land. Land plants, swamp and jungle plants, with fragments of coniferous stems, characterize the coal measures. Their organic contents, it will be seen, are widely different from those of the limestone below ; and hence the propriety of the sub- division we have stated. The limestone is usually some shade of gray ; it is frequently a pure limestone and fit for quicklime : in others it contains chert or hornstone. It has been divided in the Western States into the St. Louis limestone, the upper, the Archi- medes, the middle, and the encrinal limestone, the lower member. It is believed by many that there are two or three different beds of the Archimedes division, each of which has its peculiar fene- stella or coral (Archimedes), by which they may be distinguished from each other. They form, however, properly but one rock. The first and second divisions are remarkable for their numerous beautiful quartz geodes ; the third for its encrinal remains. The maximum thickness of this formation is between 750 and 800 feet. 146. The fossils of this limestone are extremely numerous. The piscean vertebrates differ essentially from those of the preced- ing systems. Fig. 144 (11) is a tooth of a fish from the Pittsburgh coal formation, the Petalodus Alleghaniensis (Leidy). 147. The coal measures, taken as a whole, show that, though composed of divers materials, they are connected by a continuous series of events of similar kinds; and also show that they are bound together, and form parts of only one period or system. They were ushered in by a deposit of coarse pebbles, which constitute a massive bed, which has been called the Millstone grit. 14 158 MANUAL OP GEOLOGY. Fig. 144. 1. Producing carbonari us. 2. Spirifer Marionensis (do.) 3. Productus . 4. Productns aequicostati.s. 5. Jlodiola. C. Chonetes ornata (Shumanl). 7. Discina. 8. Productus flemingi. 9. Alloristna Ilannibalensis (do.) 10. Orthis swallovi. 11. Petalodus alleghaniensis. CARBONIFEROUS SYSTEM. Fig. 145. 159 1. Actinocrinus chrystil. 2. Cyphaspis girardeauensis four times enlarged). 3. Fusilina cylindrioa. 4. Pentremites Sayi. 5. Pentremites Koninckana. 6. Pentremites pyriformis. 7 and 7 a. Conularia rernuelii (half the size). 7 a. surface enlarged. 8. Archimedes Wortheni. 160 MANUAL OF GEOLOGY. The system, litholog'.cally considered, is composed of grits and shales, coarse and fine-grained sandstones, black, gray, and bitu- minous shales, fire-clays, with their superimposed coal seams and beds of clay and ironstones, forming together a series of overlying deoosits, and of which many of the members are often repeated. These repetitions could only occur, as we have already explained, by successive submergences. Sometimes these areas existed as deep seas, or as shallow estuaries, which might be converted by sedi- ment into bays, swamps, and jungles ; sometimes again we find deep marine products ; then those of a shallow brackish water, as in estu- aries, the latter of which would rapidly change and become an area for the growth of vegetables which in turn would be changed into coal. A modification of this view with respect to the stationary periods should be alluded to in this place. Thus, instead of maintaining a period of absolute rest during the growth of coal plants, it has been supposed that there was a slow subsidence which kept pace with the upward growth of the vegetables. Still it is evident the time came when a more complete subsidence occurred ; so complete as to submerge most perfectly the entire plant bed, and of placing them so deep in water that the whole mass was killed, and at the iarne time secured their burial under beds of sand and clay. 148. In many of the thick carboniferous systems these stationary periods are numerous. In Nova Scotia, where it is no less than 14,000 feet thick, there are more than one hundred } all of which are indicated by roots in the strata and upright trunks and stems, many of which were no doubt vast forest areas, parts of which were too dry to preserve the carbonaceous matter of a rank vegetation. These forest areas have preserved casts of trunks varying from a few inches to three feet in diameter, equalling in size those of our present forests. The annexed figures represent the ancient fern-like plants and stems of the Sigillaria. Fig. 147 (1). Alethopteris rugosa. Fig. 150, A leaflet enlarged. Fig. 148, Pecopteris Sheafferi. Fig. 146, Sigillaria attenuata. Fig. 146, Sigillaria Yardleyi. Fig. 147, Odontopteris alata. Fig. 149, Sphenophyllum erosum. 149. Debituminization of Coal. In the early periods of geology of this country it was supposed that the unbituminized or anthracite coals were older than the bituminous. It is, however, now known that both varieties belong to the same epoch ; the former to rocks which have been disturbed, fractured, and broken up, and which CARBONIFEROUS SYSTEM. Fig. 146. FLORA OF THE CARBONIFEROUS SYSTEM. 161 Sigillaria attenuata (Leaqx.) 14* 162 MANUAL OF GEOLOGY. Fig. 147. roptaris rugosa (Lesqx.) CARBONIFEROUS SYSTEM. Fig. 148. FLORA OF THE CARBONIFEROUS SYSTEM. 163 Sternbergia, Nova Scotia, Jogging coal field. Sphenopteris ? Pecopteris Sheafferi (Lesqx.} 164 MANUAL OP GEOLOGY. Fig. 149. Sphenophyllum. Sphenophyllum erosum. Pecopteris (Alethropteris) lonchitica. Alethropteria. CARBONIFEROUS SYSTEM. Fig. 150. 165 Sphenopteris allied to the microloba. Nenropteris undescribed, South-western Virginia. Asteropbyllites equisetiformii Annularia sphenopbylloide* 6phnovhyllum maiginatom. 166 MANUAL OF GEOLOGY. have probably been subjected to a temperature sufficient to dissipate tlieir volatile matter. The heat required for this need not exceed 400 Fahr., especially if accompanied with the escape of steam : a degree of heat insufficient to produce a material change in the tex- tuie of the rocks themselves, or to destroy the plants imbedded therein. Or we believe it is more agreeable to all the facts now known to ascribe the cause of debituminization to heat disengaged by the collision of the masses when the upheaval of the coal measures took place. The excessive displacement of these rocks has affected every layer of the mass concerned. The obliteration of specific characters of the fronds of the ferns and other vegetable fossils show the effects of upheaval, and the sliding of the masses upon each other; a movement which could not take place without the development of heat. If heat had been propagated from below, from igneous masses, the lower rocks must have suffered a complete fusion before heat to a sufficient amount could have been disengaged to have effected the debituminization of the coal. Rocks are bad conductors of heat ; hence the necessity for its generation in the midst of the masses themselves rather than in ascribing its origin to distant heated bodies beneath. Of course we except those cases where trap is found in the immediate vicinity of beds of coal. In market coals are frequently distinguished from each other by the color of their ash ; thus there are red and white ash coals ; the former usually have the most clinker, and injure the grate more than the white ash. The white is firmer and less broken, and is regarded as the most valuable of the two. These remarks apply to the anthracites of Pennsylvania. 150. Distribution. The British provinces, Nova Scotia, New Brunswick, and Newfoundland, have large areas underlaid by the Carboniferous System. In the United States the Alleghany coal field stretches through Pennsylvania, Maryland, Virginia, Tennessee, to Alabama, a distance of nearly 900 miles, and occupies in part a width of country about 200 miles. It is not to be understood that this is now a continuous bed : it is interrupted and broken by upheavals of the strata at a period intervening between the close of the Carboniferous and the beginning of the Triassic. The beds of Pennsylvania, however, are identical with many in Ohio, and hence were no doubt continuous deposits over wide areas. Illinois, Michigan, Iowa, Missouri, and Kansas possess large and important bituminous coal fields which are only slightly disturbed, while the anthracite coal fields of Pennsylvania are greatly disturbed by upheavals being uplifted into anticlinal and synclinal axes. It is strictly mountainous, the axis of crests running north 65 to 70 east. CARBONIFEROUS SYSTEM. 167 151. Recapitulation. We have said that the Carboniferous epoch is a stand-point from which we may survey the past and future. Let us pass in review some of the leading events and changes which had already transpired in the earth's history. Physically the earth, since sediments began to collect, had undergone great changes. The plains, valleys, and lower mountains had received thousands of feet of debris, and what was once a rough pinnacled surface of pyro-crystalline rocks is now covered with sediments evenly spread out, forming the foundation of plains and gently sloping hills, suit- able for the plough and other implements of husbandry. But the vegetable kingdom has kept pace with the physical. At first the sea only produced plants, all of which belonged to the lower organisms of the kingdom; now forests of pines, inter- mingling with palm-like sigillaria, equalling in size apd height the largest of our trees, cover large areas. Among these dark green forests the ferns and fern-like plants, the lycopodiums, plants analo- gous to our ground pines, are the most conspicuous. Vegetation, to say the least, is rank, forming impenetrable jungles and thickets. We know not whether the mountains were clothed like the plains, but we find trunks of trees, stripped of their foliage, imbedded in the sandstones' of this period, which must have floated down some rapid river, and finally with its still and gentle currents were borne out to sea, where, water-logged, they sank and were buried in sand or mud. But what of the animal kingdom ? here, too, we witness pro- gress } the sea, however, is still the field in which life is strong : its fish of the higher grade verge upon reptilian forms; their teeth and scales belong to types of this class. They form as yet only two ranks, the ganoids and placoids ; but they have reached their maximum of power, notwithstanding they came in late in the Silu- rian epoch. Hence we have the reign of fish extending only over two full epochs. No mammal, either of the land or sea, or an air- breathing thing, has yet appeared, except a feeble Saurian Telerpe- ton, and the more powerful Stagonolepsis, closely allied to the Teleo- saur of the Jurassic, and the small Archegosaur of the Carboni- ferous age. But they scarcely represent power or rank, and they rather foreshadow the advent of this powerful race of the Jurassic era. But many forms have disappeared, or are about to disappear. The Trilobites no longer exist, and forms more like the present have taken their place. The Orthoceratites, which are Cephalopods, 168 MANUAL OF GEOLOGY. and were the tyrants of the seas, in the Lower Silurian stage, have also become nearly extinct, and will soon be replaced by the Belemnite of the middle ages. So also wide gaps have been made in the Brachiopodian ranks, especially in the family of the Spirifers. These and analogous forms are about to be replaced by the Os- treas and Terebratulas, many species of which have continued to the present epoch. If the law of progress is well established, the death law is equally so ; for not a Silurian species lives in the Car- boniferous seas ; yet, in all the millions which have perished, not a typical form has been lost, but new patterns, based on the same types, seem to have sprung out of the old. 152. If any epoch then in the earth's history is worthy of being distinguished above all others, it is the Carboniferous. This view is sustained by two considerations ; it is the epoch when the most valuable of all materials, COAL, was deposited, and it furnishes during its existence a magnificent exhibition of a flora unsurpassed in splendor and beauty, as in extent, by all the epochs through which the earth has passed. During this epoch there seems to have been a greater uniformity of temperature and climate than had been witnessed in any former one. Of this we may be assured by the greater number of plants which belong to the same species in distant parts of the world. The coal plants, for example, of Europe do not differ materially from our own ; many are identical species. In this particular, then, we have that kind of evidence which naturalists rely upon to prove similarity of conditions of distant and remote parts of the world. But the importance of this epoch, in consequence of the inex- haustible masses of fuel which have been preserved in its rocks, cannot be over estimated. Civilization, as we have said, is due in a great measure to the events of this remote period. Before the highest order of our plants was created, before a warm-blooded animal came into existence, before there existed in creatures a single amiable instinct, we see a full provision in the economy of nature for the wants of a future age which no event, foreshadowed, except it may have been in the immense store of fuel which belongs to this special epoch. 153. But there is another aspect under which we ought to regard the Carboniferous epoch, if we would fully understand its importance ; it is its length, which, if measured by the depth CARBONIFEROUS SYSTEM. 169 of its sediments, holds the first rank in point of duration. There is a fitness in this respect which adds immensely to the probability of the view we have taken, aside from the thickness of the sedi- ments of this epoch. In all arrangements which bear the impress of prospectiveness, there is a consistency in time and means, to the end foreshadowed. There was to be laid up in store for future ages a stock of fuel for the nations, that the development of human power and greatness should not lack in the essential material neces- sary to carry out in full the design of their creation. Time, then, was necessary in these arrangements, and coal being of vegetable origin, the slow growth of centuries multiplied by centuries, would be only adequate to the production of matter for a single seam. But many seams were demanded, and hence the depth of the strata and the prolongation of the epoch. 154. The Carboniferous epoch then standing out in bold relief from all others which preceded it, and from those which succeed, has become like a beacon from which the geologist surveys those anterior changes which ushered it in, as well as the posterior ones which have followed. It witnessed the introduction of thousands of new forms belonging to the vegetable kingdom, as well as the introduction of new classes of animals, so that the aspect which it presented had no similarity to any which preceded. The previous faunas and floras reach the commencement of this epoch, but do not enter it; and its own fauna and flora have nearly disappeared from the earth at its close. It is, therefore, a well defined epoch, having a beginning and ending, and we may say a middle term also, which marks its most distinguished and charac- teristic aspect. It is not then a sudden introduction of an epoch starting into life in its full development, but, like all others, it begins with an introduction of a minor importance with an exhibi- tion of a few new classes which increase gradually, evolving con- tinually new and striking phases as time rolls on, until we see, after the passage of ages, the full development of the characteristics which mark unmistakably an epoch entirely new in the world's history. The history of the rise and fall of nations presents an analogous aspect, rising to their zenith and importance by successive steps, until finally the acme of power and rule is attained, when, by a series of declining ones, it merges itself into a new order of things 15 170 MANUAL OF GEOLOGY. 155. Comparative View of the Devonian and Silurian Systems, Exhibiting their Relations to the Carboniferous as it Exists in Several States of the Union ; the New York Series being taken as the Standard of Comparison. New York. Pennsylvania. S.W.Virginia. Ohio. Missouri. 31 30 29 28 27 26 26 24 23 I" I 21 20 19 18 Coal measures Mt. Limest Conglomerate ? Cattskill group . Portage and Chemung group Gencsee elate Tully limestone Marcellus shale . Corniferous limestone . . . Onondaga limestone .... Schoharie grit Cocktail grit .... Oriskany sandstone ' 17 16 15 14 13 12 11 10 9 i; S a 5 4 3 2 1 Encrinal limestone Mthyris shaly limestone . Pentamerus limestone . . . Manlius water lime Niagara group Oneida conglomerate .... Utica slate Trenton limestone Black River limestone . . . Bird's Eye limestone .... Chazy limestone . . Calciferous sandstone .... Potsdam sandstone .... I CARBONIFEROUS SYSTEM. 171 In explanation of the foregoing table it may be observed that the coal measures of Pennsylvania rest upon the Cattskill group, or upper rocks of the Devonian, the Carboniferous limestones being absent ; while in South-Western Virginia they rest on the Upper Silurian. In Ohio the Cattskill group is absent, and hence the coal measures repose on other members of the Devonian. In Mis- souri, Kentucky, Tennessee, and Alabama the Lower Carboniferous limestone is present; and it rests on the rocks equivalent to the Chemung group in Missouri. In South-Western Virginia a series of salt-bearing rocks, with gypsum, belong to the Carboniferous series. The dotted lines represent the absent rocks. Fig. 151. BigUlwri* bilobn. (Sharp's Mountain.) Fig. 152. Dromatherium sylvestre. CHAPTER XV. PERMIAN SYSTEM PHENOMENA MARKING THE CLOSE OF THE PALAEOZOIC DIVISION AUTHOR OF THE SYSTEM, AND DERIVA- TION OF ITS NAME CHANGES IN THE ORGANIC REMAINS PERMIAN OF THE ATLANTIC SLOPE DEVELOPMENT IN NORTH CAROLINA SYSTEM DESCRIBED UNDER THE NAME CHATHAM SERIES, FOSSILS, ETC. 156. THE Palaeozoic series closes with this system. Not because there is anything peculiar in the lithological character of its rocks, but because it was during the deposition of the strata which belong to it that the animals and plants which are closely related to those of the preceding epochs mostly disappear; while in the system which succeeds it all the Palseozoa are absent. In Europe, in 18467, about 166 species belonging to this system had been described, of which 148 are said to be characteristic of it, and 18 were found in the subjacent Palaeozoic rocks. Its name is derived from the ancient government of Perm, Russia, where the series consists of sand- stones, limestones, and conglomerates, &c. Phillips and Murchison, in England, had already proposed separating the magnesian lime- stone series and a portion of the sandstones of the superincumbent from the New Red, and forming therefrom a distinct system. The base of this system is the Rotheliegende of the Germans. It rests unconformably upon the Carboniferous. Hence, it appears that in Europe, after the close of the latter period, and after a state of comparative rest, the earth's crust was once more broken up by igneous forces, the Palaeozoic rocks were tilted up, and hence all the subsequent rocks were deposited on their upturned edges. (172) PERMIAN SYSTEM. 173 From these physical movements we have reason to expect that changes equally great in the organic kingdoms must have followed, for it seems to be a law that terrestrial movements have resulted in bringing about essential changes in the distribution of water and other physical conditions which affect unfavorably life in the aggre- gate ; for in the overlying deposits we miss the forms which are Familiar to us, and find them replaced by new ones, which are fitted for the new conditions which have resulted from those changes. But species die out, and are replaced by new ones during periods of quietude, and even quite a number may survive a period of disturbance, and pass from one system to another. This system, in Germany, is formed essentially of three mem- bers, the Rothetodteliegende, Zechstein, and Kupferschiefer, and in England by the Lower New Red Sandstone and Magnesian Lime- stone. In Russia there are also beds of limestone, which have been identified with the Zechstein and Magnesian limestone, and which are also surmounted by marls, spotted sandstones, and conglome- rates. In all the countries of Europe the foregoing members are quite similar lithologically ; besides, they are connected together by a similarity of fossils. 157. There are many important changes in the fossils of this era which should be noticed. Taken as classes the Brachiopods have diminished considerably j but there are still remaining in the Permian 30 species at least, of which 10 are common to the car- boniferous ; that is, about one-third be- belong to the latter. The most common Brachiopod is the Productus horridus, fig. 153. The Gasteropods and Cephalopods have both greatly diminished in num- bers. Goniatites, Nautili, and Ortho- ceratites are almost all unknown in the Permian. The Crustaceans are represented by Productus horridus. the genus Limulus. The fishes are peculiar to the system. In Russia the limestones, in England the Dolomitic conglomerate, and in Germany the Kupferschiefer, contain bones of Thecodont Saurians. There are two extensive areas over which the Permian is proba- bly spread in the United States, the Atlantic slope, and a large 15* MANUAL OP GEOLOGY. portion of the Western States and Territories. I he lithological characters are quite different in these two sections of the Union. We shall select only a few localities for the illustration of this series. Greenfield, Mass., and the adjacent country in the neighborhood of Turner's Falls, give us an interest- ing series, the lower part of which we place in the Permian. 158. The Greenfield Section embraces the following beds : Fig. 154, a coarse red conglomerate : 6, red sandstone with a few pebbles ; c, gray brecciated conglomerate j A, trap. This series, from a to A, is about 2200 feet. The trap divides the sandstone, and we find on the east side of it 1, red shale and red sandstone, which are impressed with the earliest foot- prints which hitherto have been regarded as the prints of birds' feet. 2. Brecciated conglomerate. 3 and 4. Red sand- stone alternating with pebbly beds. 5. Shaly sandstone with footprints. 6. Red sandstone. 7. A dark-colored shale with footprints. 8 and 9. Crushed beds consisting of fine-grained calcareous sandstones. 10. Gray sandstone and dark-colored flags. 11. Slates. 12. Coarse conglomerates. 13. Dark- colored flags with footprints, at a place known as the Horso Race on the Connecticut River. 14 and 15. Slates alternating with pebbly beds. They form the upper part of this series. The first 2200 feet only are regarded as Permian. The casts of vegetable stems agree in character with the lowest sand- stones in North Carolina. 159. The following section, which is only refer- red to, is similar to the preceding in part. It illus- trates the beds which we have called the Chatham series, in North Carolina. It is the most southerly series upon the Atlantic slope. In the ascending order, there are conglomerates from 50 to 60 feet thick ; red and brown sandstones and marls, which terminate in gray sandstones, which sometimes be- come reddish after long exposure to the air. We regard the Lower Red sandstones as equivalent to the German Rothetodteliegende. Upon this sand- stone repose the bituminous slates, coal, and black- band, succeeded by gray, sandy shales, finely rippled, and marked also with insect trails, followed by repetitions of bituminous shale, coal, black-band, and fire-clay. Then follow thin beds of greenish. PERMIAN SYSTEM. 175 calcareous shales, containing magnesia, alternating, repeatedly, with bituminous shales. The whole thickness of these shales is at least 600 feet. Gray sandstone follows, which is often finely rippled ; and then, beds of conglomerate, alternating with bluish, non-bituminous shale, with lignite, and stems of silicified wood, together with greenish, sandy, and gray shales and sandstone, with cycads, gray sandstone, and mottled or spotted sandstones and marl. Near the top of the series, in many places, there is a compact gray magnesian limestone, which contains a few fossils. The Triassic series is, probably, unconformable to t"he Chatham series. The upper part is often highly charged with pebbles; and on the Dan river, it is coarsely brecciated. These conglo- merates are, undoubtedly, parallel with those on the Connecticut river, at, or near the Horse Race. 160. Fossils of the Lower Red Sandstone Shales, Black-band, &c., Fig. 155. Chondrites interruptus. In the upper part, below the bituminous shales, we have found a biconcave vertebra, and other bones, supposed to belong to a Thecodont Saurian. (Fig. 160). Fossils of the Bituminous Shales, Coal, Black-band, Ore, &c. The most interesting, is the jaw of an insectivorous mammal, fig. 152, twice the natural size the Dromatherium sylvestre. It is the lower jaw, and belonged to the oldest known mammal. The next most interesting fossil, is the Rutiodon Carolinensis, fig. 157; a. a premaxillary bone ; b. nostrils. The premaxillary is subcylindrical, and consists of one solid piece. The original is 30 inches in length. The teeth of this Saurian are all fluted more or less distinctly ; in which respect it differs from the Clepsisaurus of Lea, fig. 158. 1, 2, 8, 4, 5, 6, 7, 8, represent the teeth of the Clepsisaurus. 7 and 8, are transverse sections. The upper jaw of the Rutiodon is nearly cylindrical, as it is pro- longed in front of the nostrils, which are just anterior to the large eye-sockets, and descend vertically, like the blow-holes of a ceta- cean. Notwithstanding this prolongation of the snout, and its spoon-like enlargement at its end, it differs materially from the Teleosaurus of the Lias. (Fig. 158 ; 11, 12, different forms of the teeth of the Palaeosaurus.) The Chatham series, and indeed, the lower beds of the entire formation, which ocupy the Atlantic slope, rests upon either the pyrocrystalline rocks, or the slates of the Taconic System. In North Carolina, beds of porphyry support the lower red sandstone, and 176 MANUAL OF GEOLOGY. hence we are deprived of a clue to the age of the series, by the absence of all the systems between the Taconic and Carboniferous. In the Western States and Territories, however, the so-called Per- mian, first recognised, we believe, by Mr. Meek, succeeds the Carboniferous, with which it is also conformable ; and many Car- boniferous species are intermingled with those fossils, which are supposed to be Permian species. There is, therefore, reason for raising the question, whether the upper beds, which are regarded as Permian, may not be classed with the Carboniferous. 161. Distribution. Upon the Atlantic slope, especially in North Carolina, the evidence of the Permian age rests on the presence of Thecodont Saurians, which in England are referred, by the best geologists, to this system. In North Carolina, this view is strengthened, by the presence of the Trias, which is superimposed upon the beds which contain the Saurians in question. There would have been less objection to this view, no doubt, had the Droma- therium been found in the Trias, or in the rocks of the Mesozoic age. Assuming the observations of many geologists respecting the Per- mian elsewhere in this country as correct, it is evident this system occupies a wide area westward. It exists in Illinois, Kansas, Nebraska, at the Black Hills, Missouri, and New Mexico. "Its boundaries, however, are undetermined. Labyrinthodont of the Trias restored, with its foot-prints. PERMIAN SYSTEM. 177 Fig. 155. PLANTS OF THE CHATHAM SERIES. Chondrites interruptus. 178 MANUAL OF GEOLOGY. Fig. 156. PLANTS OF THE CHATHAM SERIES. Sphenopteris Egyptiaca. o Saurian Teeth of the Bitumi- nous Slates of the Chatham Series, N. C. (Twice natural si.e.) PERMIAN SYSTEM. Fig. 157. 179 Eutiodon Carolineasia. a. Premaxillary bone. 6. Nostril*. 180 MANUAL OF GEOLOGY, Fig. 153. i, 2, 3, 4, 5, 6, 7, 8. Teeth and sections of the teeth of the Clepsisaurus Pennsylvanicus. 9. Pos- terior of the skull of the Dictyocephalus elegans, Leidy. a. Oecipitals. b. Parietals. c. Frontals. d. Post Frontals. t. Post orbitals. /. Squamous. g. Mastoids. h. Typanics. t. Zygomatics. 10. Cra- nial Plate of tho Dietyocephalus. II and 12. Teeth of a Palaeosaurus ? 13. Phalange of the !>' i - Tooth of a Pycuodont. PERMIAN SYSTEM. 181 Fig. 159. 1. Dermal Plate of a Saurian. (Natural size.) Cranial Plate of a Saurian (undescribed.) Cranial and dermal plates of the kind represented above have been found only in the upper part of the lower sandstone. 16 182 MANUAL OP GEOLOGY. Fig. 160. SAURIANS OP THE CHATHAM SERIEH. 2. Biconcave Vertebra of the Clepsisaurua. 1. Doable-headed Kib of the Rutiodon. The strong analogy which exists between the Saurians of the Chatham series and the Bristol conglomerate, Eng., has led us to place the series in the Permian System, notwithstanding the ex- istence of the mammal already referred to. The vertebrae are not only biconcave, but in other important respects resemble those of the Thecodonts of the English beds which are regarded as Permian. PERMIAN SYSTEM. 183 Fig. 161. FISH REMAINS OF THE CHATHAM SERIES. Rabdiolepis speciosus. Stile of the fin of a fish. 184 MANUAL OP GEOLOGY. Fig. 162. LABYEINTHODONT OF THE CHATHAM SERIES. Head of the Dictyocephalus elegans (Leidy). This skull belonged to a Labyrinthodont, and is probably allied to the Archegosaums. The cranium is partially restored ; the pos- terior part is complete, exhibiting the double condyles of this order of Saurians. Fig. 1589. The plates are designated. The restoration was made by Prof. Leidy. CHAPTER XVI. TRIASSIC SYSTEM DIVIDED INTO THREE MEMBERS BASE OP THE MESOZOIC DIVISION MINERAL CONTENTS ITS FAUNA AND FLORA IMPRINTS OF THE FEET OF BIRDS AND BATRA- CHIANS. 162. THIS series is composed of three distinct members : the Bunter sandstone, the inferior, the Muschelkalk, the middle, and the Keuper, the superior member. The lower and upper are shoro deposits ; the middle, a deep marine deposit, which is, no doubt, partly a mechanical, and partly a chemical formation. It is fre- quently absent, as in England and America. It is rich in molluscs, and hence its name. Although this system is the base of the Mesozoic division, it is still conformable to the Permian, presenting, in this particular, an anomaly, when the relative position of the latter is considered ; for this system, the Permian, is discordant to the Carboniferous, upon which it rests. It seems, therefore, there is a break in the series at the wrong place; it should have been at the commencement of the Mesozoic division, the base of the Trias. The progress of discovery has brought to our knowledge much that tends to obliterate the strong lines of demarkation between the Palaeozoic and Mesozoic divisions. Quite a number of Palaeo- zoic genera pass up, and are associated with those of the middle division. Still, there are grounds for regarding the Trias as indi- cative of a new era, by the introduction of a new class of vertebrates, the birds ; such an event certainly should be marked in our sub- divisions of the strata. 163. This system contains beds of rock-salt, brine springs, and gypsum, and hence has been called the Saliferous System, and hence, too, is important for its valuable mineral contents. But its fauna and flora confer a special interest upon the system The animals are peculiar; the Saurians, for example, are Labyrin- thodonts, which partake strongly of the Batrachian type. In 16 * (185) 186 MANUAL OF GEOLOGY. Europe, a single mammal has been found, the Microlestes, in its upper member the Keuper. But our interest in the series is greatly heightened by the evidence that birds appeared upon this planet, for the first time during this epoch. The inference to this effect, is based on foot-prints upon the strata, which possess all the characteristics of this class of bipeds a foot-print, pro- vided with the three toes in front, and the requisite number of joints to each toe. Some years ago, the enormous size of the foot- prints, created some doubt of their having been made by birds ; but discoveries of the remains of birds of gigantic stature, in New Zealand, have dispelled those doubts. Fig. 163, imprints of birds' feet, in the shale of Turner's Falls, Mass. In similar shales, and near the same horizon, fish remains are numerous. Fig. 164 is the Eurinotus ceratocephalus ; it is an unique specimen, exhibiting appendages upon the front part of the head. It is associated with the genus Ischypterus, which occurs at Sunderland, Mass. At Boonton, N. Y., similar beds of shale contain fish remains, of the same species as those of Turner's Falls and Sunderland. In North Carolina, fish remains of the same family, occur in the upper sand- stone. 164. The lithological characters of the Trias are exceedingly varied. Red sandstones and shales, often mottled, prevail, but gray and red conglomerates, red shales, calcareous shales, of a reddish tint, bituminous shales, of a black color; also, black, purple, green, and spotted shales, which are not bituminous or commpn. As in other systems, its base is a conglomerate. Near Turner's Falls, in the vicinity of Greenfield, the conglomerate is gray, and numerous beds of different lithological characters succeed, in the order represented in fig. 154. This section was referred to in the notice of the Per- mian system, but is more particularly described in this place. Thus, from a to A, conglomerates, red sandstone, usually coarse, and often pebbly, embracing a thickness of over 2000 feet. 165. A. Heavy beds of greenstone which divide the formation on the east side of the greenstone. 1. Red shales. 2. Conglomerate traversed by a trap dyke. 3. Red sandstone. 4. Red sandstone alternating with pebbly beds. 5. Shaly sand- stone with footprints of birds. 6. Red sandstone. 7. Thin shaly dark-colored beds with footprints. 8. Broken and crashed beds of fine-grained calcareous sandstone. 9. Fine-grained calcareous sandstone. 10. Gray sandstone and dark-colored flags. 11. Slates. 12. Coarse conglomerate. 13. Gray and dark- colored flags and slate with footprints. 14. Slates, alternating with pebbly beds TRIASSIC SYSTEM. 187 Fig. 163. IMPRINTS OF FEET. Imprints of the Feet of Birds. Imprints of the 188 MANUAL OP GEOLOGY. Fig. 164. FISH REMAINS. 1. Eurinotus coratocephalus. TRIASSIC SYSTEM. 189 some of which are coarse. This series embraces a thickness of not less than 5000 feet. The materials composing these beds are derived from the neighboring talco- micaceous slates and granites. In the conglomerates large fragments of inica slate are common exceeding a foot in diameter they are both angular and rounded. We may recognise two movements while the foregoing sediments were being deposited ; the first, immediately preceding the deposit of the gray conglomerate, No. 1 ; the second, towards the close of the period, at No. 12, and which seems to have been frequently repeated until its close. 160. The Triassic series are exposed in Wake and Orange counties, N. C. The railroad leading from Raleigh to Hillsborough passes over them nearly at right angles to the dip of their beds. At Morrisville, 12 miles from Raleigh, the lower conglomerates are visible and in proceeding to Durham Station the dip may be seen at numerous places, inclining at about an angle of 10 to the north-west. This being the regular dip of the series here, we conclude that there is an un- conformability between these beds and those which belong to coal measures of Deep river, for there the dip is south and south-west. It is also fully ascertained that the latter are absent, and the former repose on the older slates. This series is remarkably well developed on the North Pennsyl- vania Railroad, beginning near Fort Washington Station, Pa. This road crosses the entire series. At Gwynedd Station, the tunnel cuts through a part which corresponds with the Phoenixville Station. Several beds of black and green slates frequently occur, as partings between heavy beds of a tough, brownish, granular sandstone. This part has been disturbed, and seams of calcspar are common in the tunnel, in which, also, may be seen solid bitumen, or coal. A Posidonia occurs at Gwynedd, and frequently, worm-tracks, and rarely a calamite. After passing the tunnel, the rock is mostly a shaly sandstone, with fucoids. This belt, between Gwynedd and the next station north, corresponds to one near Greenfield, Mass. 167. The most interesting relics of the Trias, as already stated, are the imprints of the feet of birds, inasmuch as they furnish indica- tions that the earliest existence of this class of animals is found in this formation. The imprints already referred to were made by a biped. The substance of the rock was soft at the time they were made, and hence there is a want of sharpness in the outline of the foot. Birds of gigantic size strode along the beaches of olden time, if the imprints of their feet furnish a criterion of size and weight. For example, there are footmarks in the Trias of Con- 190 MANUAL OP GEOLOGY. Fig. 165. Trails of Insects. necticut, which measure seventeen inches from the heel to the point of the middle toe. Others are small, and resemble the im- prints of the feet of small shore-birds, not unlike those of the pre- sent day. But imprints of various kinds are common upon the fine sandy deposits ; even insects have left their trails. Whoever is at pains to observe the surfaces of fine plastic clays after a shower will find trails of larva, and also of perfect insects, around the parts of water which are left stand- ing by roadsides and in undisturbed fields. Fig. 165 shows the trail of what appears to have been made by larva of some dipterous insect, pre- serving also the impression of rain- drops. (See also pi. vi. American Geology, figs. 105, 106, 107, 108). So also in the ancient Trias, at Turner's Falls, furnish trails of insects, of which fig. 109, of the same work, is an example. 168. The Mollusca (Entomostraceans) of the Triassic sandstones are by no means numerous. The Posidonia (Estheria) minuta is regarded as a characteristic fossil of this series, and occurs in North Carolina. Fig. 166 represents several species of forms allied to the Posidonia. In North Carolina, and also in Massachusetts, the most common fossils belong to the vegetable kingdom. Of these an interesting family of plants are well known, as Cycades, which are among the vegetable products of Australia. The plants represented in the plates 168, 169, are regarded by Professor Heer as indicative of the Keuper, the upper mass or division of the Trias, and they are particularly noted as being infra Liassic, which is a very important fact, inasmuch as they belong to the superior mass, and are widely separated from the Chatham series by sandstones and conglomerates. These facts give charac- ter to the conclusion that the Chatham series represent a part of the Permian system.* Other plants, belonging to the Lepidodendron and ancient coni- fers, are not uncommon in the plant-beds of the Trias, and a cha- racteristic one is probably (fig. 172) an Albertia latifolia ? See Note B, page 280. TRIASSIC SYSTEM. Fig. 166. ENTOMOSTRACEANS OF THE BUNTER SANDSTONE. 2 191 1. Myopia pekinensis. 2. Cypris. 6. Myopia curta. 4, 3. P^suonia (Estlieria). 5. Stylorhyn- chus unsymmetricus. 7. Posidonopia rhomboidea. Fig. 167. FISH REMAINS. 1. Scales of the Eabdiolepis elegans, E. 2. Cranial bone. 3. Bone of the Rabdiolepia. 192 MANUAL OP GEOLOGY. Fig. 168. PLANTS OF THE TRIAS. Neuropteris ellingtonensis. Strangerites otiliquus, E. Pterozamiteg obtnsus, E. TRIASSIC SYSTEM. Fig. 1C9. PLANTS OP THE TRIAS. 193 Gutbieria Carolincnsis, . Pterozapiites obtusifolius, E. Pterozamites spatulatus, E. There are three important localities which furnish plants : 1. The quarry of Mr. House, of Haywood, situated about one mile from the village, upon the Haw River. 2. Lockville, formerly known as Jones's Falls, upon Deep River. 3. Ellington's, about five miles west from Lockville. The slates which contain them are usually dark colored, but not bituminous, though at Ellington's there is a seam of bituminous coal about two inches thick. These beds are immediately above beds of conglomerates, or else interlaminated with them. No animal re- mains, as fish scales, the estheria, or mollusks, have yet been found associated with them. Similar beds occur only at other points in the valley of Deep River, far above the bituminous slates, which furnish coal, and the remains of the Clep. sisaurus, Rutiodon, &c. 17 194 MANUAL OF GEOLOGY. Fig. 170. PLANTS OF THE TRIAS. Pterozamites gracilia. E. Pteroiamites peotinatua. E. TRIASSIC SYSTEM. 195 Fig. 171. PLANTS OF THE TRIAS. Taxodites brevifolia, E. Lepidodeudron. Walehia variabilia. E. Taxodites gracilis. (Enlarged one-halt) 196 MANUAL OF GEOLOGY. Fig. 172. PLANTS OF THE TRIAS. Albeiti&latifoliaf TRIASSIC SYSTEM. 197 Fossil ferns are equally common, and sometimes they are found with fruit dots. The epoch of the New Red Sandstone, or Trias, terminated in numerous disturbances of the earth's crust, for in Europe as well as in this country the fine sediments are interlaminated with coarse gravels, and frequently these beds contain large blocks of angular rocks, or those which are only partially rounded. Beds of con- glomerate, made up of stones of the size used in paving streets, are by no means uncommon. There is therefore strong evidence that the oscillations of the earth's crust were of common occurrence, and led to a frequent change of level, and of course to a change in the direction of rivers and currents. 169. In connection with these physical changes the student will find the formation traversed by the pyroplastic rocks, greenstones, porphyries, and amygdaloids. Igneous outbursts were therefore common, and were probably the direct causes which produced the oscillations of the earth's crust, already referred to. We therefore regard the Triassic epoch as one distinguished for the phenomena we have referred to. The formation of rock salt and gypsum were undoubtedly connected with these disturbances, giving origin to extensive isolated sheets of water, where evapora- tion of sea-water furnished beds of salt and gypsum. 170. At the close of the Triassic we find several genera of fossils which are common to the Palaeozoic division ; for example : the Cyrtoceras, Orthoceras, Goniatites, Murchisonia, Euomphalus, and Porcelia. In the Trias we find the following genera, which make their first appearance here, and finally become common in the Mesozoic division, viz. : Ammonites, Belemnites, Cardita, Trigonia, Ostrea, and Plicatula. The association, then, of the older genera with the newer ones, which soon prevail to a great extent in the Mesozoic division, serves to efface the sharper lines of distinction which had hitherto pre- vailed respecting these two great periods in the earth's history.* * The Clathropteris rectiusculus, H., discovered by Prof. Hitchcock at East Hampton, towards the upper part of this series, does not prove that the pnrt in which it was found belongs to the Jurassic ; it differing specifically from the Jurassic species of Europe; inasmuch, too, as the genus belongs also to the Triassic sys- tem. Hence it would be as consistent to claim this plant for the latter as for the former system. 17* CHAPTER XVII. JURASSIC SYSTEM IMPERFECTLY REPRESENTED IN THIS COUNTRY ITS POSITION ON THE CONTINENT OP EUROPE ITS SAURIAN REMAINS CHARACTER OF THE SEDIMENTS DIVIDED INTO FIVE STAGES THE LIAS HAS THREE GROUPS THE \VEALDEN CLOSES THE EPOCH. 171. So little is known of the Jurassic system in this country, that we prefer to describe very briefly the European series, as this epoch, as we find it here, is only imperfectly represented. In certain points of view, it is interesting, as well as important. It occupies a central position on the Continent of Europe, being well developed in the Jura Mountains, lying between France and Switzerland ; especially the Liassic stage, which is regarded as the argillaceous base of the system. It is in this system, that Saurians attained a maximum develop- ment of this class of vertebrates ; they were both numerous, and of immense size. Two very remarkable genera have been de- scribed in almost every treatise upon geology, viz. : the Icthyo- saurus, and Plesiosaurus ; the former is distinguished by a short, and the latter by a long neck. These reptiles were aquatic or marine, and were furnished with paddles of great power, for moving swiftly through the water. The eyes of the Icthyosaurus were large, and furnished with peculiar envelopes, or a special appa- ratus, which enabled them to adapt the vision to the distance of the object it wished to see. The Teleosaurus, another genus belonging to this epoch, was furnished with legs, instead of paddles, and in its general appearance, resembled the Gavial of the Ganges. It was in this epoch, also, that flying lizards, or Pterodactyles, seem to have been common, and to have contributed, by their organiza- tion and habits, to its singularity. In the organization of the rep- tiles of this epoch, it is easy to recognise in the Saurian type, the bird, fish, and cetacean. (198) JURASSIC SYSTEM. 199 The sediments of this epoch are fine, and well adapted to the preservation of fossils ; and to this, we may attribute much of the exact knowledge we have obtained of the peculiar animals, and of their organization. Frequently, their skeletons are entire, or their parts so closely united, that it has not been difficult to restore their exact forms. 172. The Jurassic system has been subdivided into five stages : the Lias, Lower Oolite, Oxfordian, Upper Oolite, and the Wealden series. The whole series, in Europe, has a thickness of about 1030 feet. The Lias is divided into three groups: the Lias Inferior, the Middle and Upper Lias. The passage from the New Red to the Lower Lias, is quite distinct. The latter consists of a fine white, micaceous sandstone, which often abounds in the remains of fishes; hence, it is blackened by animal matter, in the form of bitumen, and though the stratum is thin, it is recognisable over large terri- tories. The Grryphea arcuata, fig. 174, 2, is one of the character- istic fossils. The Middle Lias, is a blue argillaceous limestone, often striped, and abounds with fossils, as the Spirifers, Pentacri- nites, Pectens, Ammonites, and Fish; among which are recognisea the genus Tetragonolepis, fig. 173, and an Ichthyodolerite of the genus Hybodus, fig. 194, 1. The Upper Lias consists of a dark- colored shale, particularly at Whitby, in England, and has been em- ployed in the manufacture of alum. Fig. 173. Tetragonolepis. 1941. 200 MANUAL OF GEOLOGY. Fig. 174. JURASSIC FOSSILS. Trigonia. Ammonites j Aucyloceras matheroniensis. JURASSIC SYSTEM. 201 The Lower Oolite consists of alternating Fig. 175. masses, or bands of limestones and clays. The particles forming the limestone, have the ap- pearance not unlike the roe of fish, and hence the name Oolite. The Lower Oolite contains good building materials, and some inferior iron ores. This group is made up, in Eng- land, of Inferior Oolite, Fuller's earthy Stonesfield slate, Brad for delay, Great Oolite, Forrest marble, and Cornbrash. The group of Middle Oolite consists of five members : Kelloway rock, Oxford clay, lower calcareous grit, coral rag, and upper calcareous grit. The group contains Gryphea dilatata Ammonites jason. The Upper Oolites con- sist of Kimrneridge clay, Portland sand, and Portland stone. The Wealden series brings the Jurassic system to a close. It is mostly a fresh water deposit, and is more fully developed in Eng- land than on the Continent. It consists of the Purbeck beds, Hastings sand, and the Weald clay. The fossils of this period are Unios, Cythere, and gigantic bones, belong- ing to an herbivorous land reptile, the Igua- nodon, whose remains are also associated with an enormous carnivorous reptile, the Mega- losaurus. The beds which are described in the ' preceding paragraphs, as forming the Wealden, are now referred, by several accom- plished geologists, to the Lower Cretaceous; and it should be observed, that Prof. Leidy has recognised fossils in this group, which indicate the existence of the Wealden in Nebraska The Jurassic system is not represented in this country by the presence of all the European members, though, in the far West, future investigations may prove that it is as fully developed as in the chain of the Jura. The annexed section, fig. 175, is designed to show its relations, as it exists in the region of the Black Hills of Nebraska. 173. Black Hills of Nebraska. Thus, 1. Granite nucleus, around Section Black Hills of Nebraska. 202 MANUAL OF GEOLOGY. which the sediments have been deposited. 2. Metamorphic sedi- ments, probably the Taconic system. 3. Potsdam sandstone, the only visible member of the Silurian system, and resting, uncon- formably, upon the Taconic series. 4. Carboniferous system, con- sisting of gray limestones and reddish grits. 5. Permian system. 6. Jurassic, consisting mainly of the Liassic stage. 7. Creta- ceous. The Liassic series of this locality, consist of shaly beds of dark brown, and also yellowish sandstones, containing Belemnites, Pentacrinites, an Avicula, and an Area, of Jurassic types. The vegetable fossils of the Jurassic system, consist of Zamias and Cycadeas, resembling those which illustrate the New Pted Sandstone of the preceding chapter. 174. Distribution of the Jurassic System. The geographical area occupied by this system is not determined. It is, however, supposed to extend along the eastern slope of the Rocky Mountains, from the northern part of the British possessions in America, to New Mexico. It has also been recognised upon the head waters of the Yellowstone. It is unknown upon the Atlantic slope; at least the evidence of its existence is not reliable. Liassic Fauna and Flora regt .red. 1. Flegiosaurus. 2. Ichtbyosau us. 3, 5. Pterodactyle. 4. Cycad, ic. CHAPTER XVIII. CRETACEOUS SYSTEM CHARACTERISTICS OF THE MESOZOIC DIVI- SION DERIVATION OF THE NAME CRETACEOUS LOWER DIVI- SION THE GREEN-SAND LITHOLOGICAL CHARACTERS FOSSILS OF THE GREEN-SAND. * 175. THE Mesozoic, which closes with this system, presents such peculiar aspects that its separation from the Palaeozoic and Caino- zoic was justifiable. This separation is based upon its flora and fauna, particularly the latter. At this day it is safe to assume that this division is sufficiently examined to assure us that we know its leading characteristics, which may be summed up in a few words. In its early stages reptilian forms of life were its most striking features. They stood out in such bold relief that they have been called the master existences of that age. We may refer to the Enaliosaurs of the Lias, and the Labyrinthodonts of the Trias. These, however, have all passed away, with the massive Megalo- saurs and Iguanodon of a later period in this division of geologic time. But this division is also noted for the absence of mammals, excepting those which are of small dimensions. This, we say, must be received as a striking fact, not resting on conjecture, for reliable observations establish the abundance of reptiles, fish, and mollusks of forms peculiar to this period, while the mammals, if they had occupied a prominent rank in this ancient fauna, would have been also brought to light. It is true, that within the last eighteen months quite an addition has been made to the list of small mam- mals, no less than fourteen species having been added from the Purbeck beds of England, some of which are closely allied to the Marsupials, which occupy a low grade in this class. This is a sig- nificant fact in itself. These, however, dwindle into insignificance, when compared with Ihe hosts of marine and land reptiles, which were truly the master vertebrates of this epoch. With this division, too, we find one of the ranks of fish the Ganoids diminishing in importance near (203) 204 MANUAL OF GEOLOGY. its close. While, at the same time, the Ctenoids and Cycloids, two new classes, begin their existence, which are destined to fill a wide space in our own time. In the last series of the Mesozoic age the cretaceous rocks, the dying out or extinction of many races which had before been strong and powerful, the introduction or creation of classes destined to multiply upon the earth, to make up in num- bers for the lack in force and individual strength, are great and significant facts of the period. Dynasties come to a close with the cretaceous, and dynasties begin ; but they simply foreshadow their reign during the last third of the cretaceous system. We reach the same general results from a consideration of the vegetable king- dom. It is only at the close of this system that .dicotyledonous trees, those which bear our favorite fruits and flowers, begin to make their appearance. They were created almost contemporaneously with the Ctenoids and Cycloids, the great classes from which we cull the favorite fish for our tables. Surely, such facts are not to be ranked as accidents. 176. This system derives its name from the well-known sub- stance, white chalk, used so extensively in marking. It is subdivided into Lower and Upper Cretaceous groups, which differ materially in their lithological characters. The lower group is widely known as the Green-sand, and in many places simply as marl, as in New Jersey. This group consists of six members, the most important of which are those beds of Green-sand (omitting the potter's clay beneath), which are separated by intervening beds of sand of various colors. The name of the Lower Cretaceous group is derived from small rounded particles of a green color, of the size of coarse gunpowder, and which consist mainly of silicate of iron. These are so nume- rous that a green color is frequently imparted to the bed. There is but a slight difference in the mineralogical characters of the three beds, though the upper contains fossils which do not occur in the lower. The lower or first bed of Green-sand supports a bed of reddish or yellowish sand quite ferruginous ; and so the second supports a sand bed similar to that upon a sea beach. Although the presence of green grains will not in certain cases be sufficient to distinguish this part of the series from other rocks, as there are many locali- ties where the green grains have been carried up into the Miocene beds. The fossils, however, are quite characteristic of the forma- tion. The lower bed contains Exogyra costata, fig. 176 (1), Tere- CRETACEOUS SYSTEM. Fig. 176. FOSSILS OF THE GREEN-SAND. 205 1. Exogyra costata. 2. Cuculea vulgaris (cast). 3. Terebratula Sayi. 4. Torebratula fragilis. 3 Janira quinquecostata (Neooomian). 6. Pecten quadricostata. 7- Terebratula Harlani. 8. Os 18 206 MANUAL OP GEOLOGY. Fig. 177. Belomnitella Americana (Morton). Belemnitella compressa, . bratula Sayi, (3); Ostrea falcata, (8) ; Terebratula Harlani, (7), and T. fragilis, (4); Cucullea vulgaris, (2); Janira quinquecostata, (5); Pecten quadricos- tatus, (6). In North Carolina the Green-sand admits of the same division as those which have been pointed out by Professor Cook, of New Jersey, but it is believed that the lower bed does not come to the surface; and besides, the fossils are less numerous than in New Jersey, and the marl itself contains a larger proportion of sand. The lowest bed upon Cape Fear is sandy below, and argillaceous above, and supports a thin bed of white Miocene marl, the Eocene being absent. 177. The following scries Illustrates the relations of the Lower Cretaceous rocks in New Jersey and North Carolina. (Fig. 178.) 1. Fire clay of Woodbridge, N. J., or pure potter's, with sands and clays of various colors, resting upon the Triassic series. 2. Green-sand. 3. Sand-colored brown, yellow, Ac. 4. Green- sand. 5. White-sand. 6. Upper Green-sand. 7. Sand and shell marl miocene. 8. Sand. Fig. 179. Section upon Cape Fear Kiver, N. C. 1. Marine sand. 2. Brown earth. 3. Brick clay. 4. Sand. 6. Shell marl. 6, 7, 8. Green-sand. The upper bed is argillaceous, and supports a thin bed of Miocene marl. The Eocene is absent in numerous places. CRETACEOUS SYSTEM. 207 Fig. 179. 178. In Alabama we find the Cretaceous represented at the Prairie Bluff limestone, which consists, 1st, mainly of a white limestone, containing the Exogyra costata, Voluta Sayana, Pecten 5 costatus. Beneath this, or 2d place, is a white sand, about forty feet thick, in which are numbers of the Ostrea larva, Gryphea vomer, and Pecten 5 costatus. 3d, Rotten limestone, with Cucuella vul- garis ; and, 4th, Concrete and loose sand, sand and clay, containing drift-wood, as at Choctaw Bluff, &c. 179. Extent of the Cretaceous Rocks, and summary of the lead- ing/acts relative to the formation. The Cretaceous rocks of New Jersey, Delaware, Virginia, North and South Carolina appear in rather isolated patches, but still they are probably continuous and connected deposits. In Alabama the formation is more ex- tended, and in the Valley of the Mississippi they occupy a wide extent of country. Some of the most important fossils belong to the vertebrate class. A Mammifer, belonging to the seals ; Saurians, as the Mosasaurus; teeth of sharks, the Laranas and Charcha- rias, Cephalopods in great abundance, as Belemnitellas, Ammonites, Baculites, Brachiopods, or Terebratulas, &c. The Mosasaurus, fig. 180 2, was once regarded as belonging to a distinct genus, but Saurian teeth vary much in form as well as size. The Hadrosaurus, 180 6, was an enormous Saurian closely allied to the Iguanodon of Wealden. The genus Polypto- chodon is also found in England. MANUAL OF GEOLOGY. Fig. 180. FOSSIL SAURIANS. I, 2. Toeth of the Mosasaurns. 3. Polygonodon rectns (L,eidy). 4. Pristis of the Eocene. 5, 5. Sec- tions of the Mosasaurus. 6. Hadrosaurus Foulkii (Leidy). 7. Polyptychodon rugosua, E. CHAPTER XIX. CAINOZOIC DIVISION GENERAL CHARACTERISTICS OF THIS DIVI- SION SIR CHARLES LYELL's SUBDIVISIONS OF THE TERTIARY EOCENE, MIOCENE, AND PLIOCENE, ETC. 180. WHEN the length of the three great divisions is computed by the amount of the accumulated sediments, the fact that these divisions are of very unequal length, is quite striking. The sedi- ments of the Palaeozoic divisions are enormously thick. When, however, we compare them with respect to their organic contents, the Palaeozoic fossils are insignificant, or occupy comparatively a low rank, when placed by the side of the Cainozoic representatives. Up to the close of the Cretaceous, no imposing structure belonging to the mammal class had appeared, but immediately after, or at the beginning of the Cainozoic time, herds of large mammals appear upon the stage. There are Pachyderms, herbivorous quadrupeds, whose remains have been disinterred from the plaster of Montmartre, near Paris. Mammals, then, at once assume an importance. The reptiles, though numerous, have lost their standing as masters of existence; and from this epoch, onward to the present, the mammals increase in power and rank, until, finally, man appears upon the scene, the lord of this lower creation. The aspect which the Tertiary epoch presents, distinguishes it, clearly, from all that had preceded it. It is not imagination, it is not theory, that these views are based upon ; but observation, carried on in all parts of the earth. It is a deduction from facts, which point only in one direction, and which lead to the conclusions which we have stated. Sir Charles LyelPs division of the Tertiary still commends itself to the student for its simplicity. 181. This general threefold division into Eocene, Miocene, and Pliocene, requires attention. In the first place, the divisions are determined by the numerical ratios which the extinct species in any given bed bear to the living. The Eocene expresses the dawn of 18* (209) 210 MANUAL OF GEOLOGY. the present; hence, the ratio of the extinct species to the living ones is very large, or rather, the living species in the Eocene are very small, if compared with extinct ones. About four or Jive per cent, only of the fossils of the Eocene live upon the earth or in the sea at the present. In the older Miocene, seventeen to forty per cent, of the species are living now. While in the Pliocene, or full dawn, the living spe- cies vary from forty to ninety-five. Hence, the relative age of the Tertiary beds is determined by a comparison of their enclosed fossils, with those which live at the present time. These divisions admit of subdivisions, as Lower, Middle, and Upper, by which closer comparisons become practicable. It may appear, to the student, that the classification of the Tertiary is too artificial and arbitrary, and is wanting in philosophical principles. This is far from being the case. Under its artificial dress, it covers principles of the highest importance. 182. It is found that the most recent beds contain the remains of animals and plants, all of which are species whose identity with the living is fully established. If we go back one stage, the identity of only ninety-five per cent, is established ; and if we go back still another stage, the ratio of the extinct to the living is still greater. It is a consequence, then, perhaps too plain to require a state- ment, that the relative age of a bed is fixed when the ratio of the extinct to the living is determined ; the nearer it is to the present, so much greater will be the ratio of its remains to those of our own times, and the less the ratio, the further removed it will be. Following out this idea, we soon reach a stage in our recession, when the present is unrepresented by living species. The resem- blance becomes generic, on receding still farther in time, or, on reaching the Palaeozoic period, the generic resemblance becomes too faint to be confidently asserted. The great and leading divisions of the Kingdoms of Nature, however, are still fixed, and strong, and as clearly distinguishable as at the present time. There are no monsters no unclassifiable beings, who refuse to submit to the sys- tematic arrangement of the zoologist and botanist ; all is consistent, and in harmony with the present, though the genera and species of the present have disappeared in our retrospect of the past. 183. The Tertiary consists of marine and freshwater deposits, which are frequently confined to separate basins ; and though they are sometimes spread over wide areas, yet they possess more of a CAINOZOIC DIVISION. 211 local character than the older formations. The chronology, in each case, is determined by the considerations and principles just stated. Our Atlantic coast furnishes an example, over which the Tertiaries are widely spread, and probably the Valley of the Mississippi and eastern slope of the Rocky Mountains are equally remarkable for the breadth and length of these more modern formations. On the contrary, the London and Paris basins are comparatively circumscribed, and yet have given law to our modes of investigation. 184. As a whole, the fossils of the Cainozoic division bear a stronger resemblance to those which now live than those belonging to the preceding periods. The lithological characters of the basins, and estuaries, &c., must, of course, present great differences, and hence are not de- pended upon to determine their ages. They repose upon rocks of all periods, from the oldest to those which immediately precede their own. A difficulty is met with in the investigation of the Tertiary, especially in settling its chronology, which should be noticed in this place. It arises from the limited distribution of species, or their confinement to particular seas, estuaries, &c. Thus, the fauna of the Red Sea differs materially from that of the Mediterranean ; so the influence of a particular sediment greatly influences the character of the animals which inhabit the area over which it prevails. Certain species live upon a muddy bottom ; others, upon a sandy one ; and the formation of these bottoms may have been simultaneous, and yet their faunas differ. But this kind of influence is not confined to the Tertiary deposits. But we remark again, leaving out of the view the difficulties set forth in the foregoing paragraphs, it has been found, by actual experience, that the divergences of a fauna from the present ones, of any country we may select, has so many advantages in settling the chronology of a particular basin or a series of beds, that it can- not at present be dispensed with. 185. The Eocene Formation of the Atlantic Slope. Litho- iogically, it has no unity of character. On James river, the Eocene resembles, mineralogically, the Green- Band. In North Carolina, the Eocene consists of white, soft inarls, sometimes tinged brown or drab. Beds of the same age are consolidated, and become white limestone, as upon the Neuse, twenty miles above Newbern. They rest on soft marls, and the upper layers are frequently soft, also. These consolidated beds are often 212 MANUAL OE GEOLOGY. silicious, and filled with rounded grains of sand. They rarely contain over seventy-five per cent, of lime. Higher up, on the Neuse, in Wayne county, these consolidated beds are associated with a light, laminated material, which would be suspected to con- sist of infusorial matter. It is, however, merely fine silex, with a very small proportion of calcareous matter. Similar beds of Eocene exist at Wilmington, charged with the same kind of fossils as those at and near Newbern. Between the Grove and Vance's Ferry, on the Santee river, S. C., there is a continuous, white soft limestone, extending forty miles, which belongs to this formation. Upon the Savannah river, forty miles below Augusta, the white, indurated marlj together with the soft marls, are overlaid with red clays and loam. The formation seems to be completed by a depo- sition of silicious beds, which have been called the Georgia buhr- stone. Like the Paris buhrstone, it has a rough appearance, and has many cavities. It passes into a sandstone with geodes, lined with crystals. Often, the interior of these geodes are agatized, and, in fine, passes into cacholong. Fine specimens of opal are occasionally found. The Eocene of Alabama is, perhaps, more perfectly developed than in North and South Carolina, particularly at St. Stephen's and Clairbourne. In the descend- ing order we find the following beds. 1. The superficial materials of recent ori- gin. 2. White Eocene limestone at St. Stephen's and Clairbourne, containing Plagiostonaa dumosum, Pecten Poulsoni, Scutella Lyellii, and bones of the Zeuglodon. 3. Bluish, buff, and green-colored sands, containing Cardita plani- costata, &c. 4. A kind of buhrstone; a silicious porous rock, probably a fresh- water deposit. 5. Buff-colored sands, clay and limestone. This is the base of the Eocene, and reposes upon the Prairie Bluff limestone which is equivalent to the green-sand, as it contains Exogyra costata, &c. These sands have numerous fossils which differ from those found at St. Stephen's and the superior beds of Clairbourne. At Vicksburg, on the Mississippi, the Eocene beds correspond with the upper Eocene at Clairbourne and St. Stephen's. Foreign Localities. Paris basin and London clay. Isle of Wight. The first consists of Upper and Lower, or the millstone above, the gypseous beds below, which contain the Palseotheria, Anoplo- theria, Didelphis, and many other quadrupeds. The London clay corresponds to the Calcaire grosier, of the Paris basin. Both are rich in univalve and bivalve mollusks. 186. Extent and Summary of Facts. The Eocene exists in Texas, Alabama, Mississippi, Arkansas, Louisiana, Georgia, North and South Carolina, Virginia, Maryland, and Delaware. Some of CAINOZOIC DIVISION. 213 the beds resemble the green sand, as Fig. 181. those near Petersburg, Va. Farther south, they are white marls, with about seventy-five per cent, of carbonate of lime, and from six to twenty-five per cent, of sand. These beds are fre- quently limestones. 187. Miocene. It consists of a series of strata, which are clays, sands, and shell marls, of white, green, and brown colors. The shell marl in the South, exists only in isolated beds or banks, similar to modern oyster banks. They are surrounded by sands, and the shell banks may extend a quarter of a mile, but frequently they occupy only a few feet in length. Where the banks are well formed the bottom is composed of a few pebbles eoprolites, with teeth of the larger kinds of sharks ; and hence it appears, that the Miocene was preceded by oscillations of the surface. In con- firmation of this view, some of the beds upon the Cape Fear contain green-sand and its fossils, as the Exogyra costata, Belemnitella Americana, casts of Cu- cullea, <&e. The section, fig. 184, presents the beds, and their order upon the Cape Fear, at Brown's Landing. 1. Sand. 2. Brown earth. 3. Clay, four or five feet thick. 4. Sand and pebbles. 5. Shell marl. 6, Sand, with consolidated beds, which resemble gray sandstone, containing fossils and lignite. 7. Blue clay. 8. Sand, blue clay, succeeded by sand. Sections of similar beds, upon the Tar river, near Tarboro, Edge- combe co., N. G. Tooth of an Eocene Whale. 214 MANUAL OF GEOLOGY. Fig. 182. CETACEAN OF THE EOCENE. 1, 2, 3. Different teeth of the Zeuglodon, an Eocene Cetacean. 4. Enchodus ferox, a fish of th* CAINOZOIC DIVISION. 215 Fig. 183. FOSSILS OP THE EOCENE. TTygon Caroline nsis. E. Nnmmulitcs ataic 7. Microcriiius conoidcus. E. 6. Eohynocyamus parvus. E. Echinus Rufiini. 216 MANUAL Or GEOLOGY. Fig. 184. x (~~ . o < . o.. .0. . r, c. - a .- o . - c~ 4-. /5SS ^ ft-^ >^ iB 5 /^~ 6 / Z-=^ ^~^' -^^^? -&- r 2. The fossils of the Miocene are quite numerous ; they are not all found at any one bed. A few freshwater shells are not uncommon, showing that there was land in the immediate vicinity. 188. In the immense region of the waters of the Mississippi, the Miocene has become one of the most interesting fields for geo- logical research, of any in the United States. Upon the eastern slope of the Rocky Mountains, a large extent of this formation is a freshwater deposit. The most interesting part of this field, is upon White river, in Nebraska, embracing all that part of the region which is called Mauvais Terres. This formation is remarkable for its mammaliferous remains belonging to the order Pachyderms. It is the Lower, or Older Miocene. The Pachyderms of this period, in the Miocene of the Atlantic slope, are not numerous. The Mastodon, however, is a common fossil, together with the horse and hog. From this fact it follows, that the Mastodon commenced its existence here as early as in Europe. Teeth, vertebra, ribs, the cuneiform bone of the foot, &c., have been found at distant points. At the same time, it is true, the Mastodon is found in marls and peat bogs, resting upon the upper bed of the drift in New York. Of the same age^ too, is that remarkable rodent, Castoroides Ohioensis. The earliest appearance of the Mastodon is in the Miocene. The generalization, therefore, which has been attempted relative to the age of this continent compared with Europe, is hasty, and is not well sustained. CAINOZOIC DIVISION. Fig. 185. MAMMALS OF THE OLDER MIOCENE. 21' 1. Titanotherium proutii (Leidy). Left side of the Lower Jaw, showing the triturating surface. 2. Rhinoceros nebrascensis (Leidy;. 3. Mylodon Harlani, an extinct Sloth. Big Bone Lick. Two- thirds the natural size. 19 218 MANUAL OF GEOLOGY. Fig. 186. Grinder of the extinct Horse. Mastodon, Marl Beds of North Carolina. Incisors of the Horse, N. C. Last Mo'.ur <>f the Under J