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VOLCANOES AND EARTHQUAKES. 
 
 ABSTRACT OF A LECTURE 
 
 BY 
 
 T. STERRY HUNT LL. D., F. R. S. 
 
 It is proposed in the present lecture to discuss the nature 
 and causes of volcanoes and earthquakes, with their related 
 phenomena, and to consider the reason of their peculiar 
 geographical distribution. Violent movements of the earth's 
 cnist are confined to certain regions of the globe, which are 
 at the same time characterized bv volcanic activity ; from 
 which it is reascmably inferred that the phenomena of earth- 
 quakes and volcanoes have a conunon ongin. The discharge 
 through openings in the earth's crust of ignited stony matter, 
 generally in a fused condition, and the disengagement of va- 
 rious gases and vapors, accompanied by movements of ele- 
 vation or subsidence of considerable areas of the earth's 
 surface, sometimes rapid and paroxysmal, and attended with 
 great vibratory movements, are evidences of a yieldiug crust 
 of solid rock resting upon an igneous and fluid mass below. 
 To the sani(^ conditions are also to be ascribed the slow move- 
 ments of portions of the earth's smiace shown in the rise 
 and fall of continents in regions remote from centres of vol- 
 canic activity. The unequal tension of the yielding crust 
 and the sudden giving way of the overstrahied portions are 
 ]>robably the immediate cause of earthquake phenomena ; 
 the seat of these, according to the deductions of Mallet, is 
 to be found at depths of from seven to thirty miles from the 
 surface. 
 
 A brief description of the plienomena of volcanoes will be 
 necessary as a preliminary to the inquiry which constitutes 
 the object of our lecture. Volcanoes are openings in the 
 earth's crust through which are discharged solid, liquid, and 
 gaseous matter, generally in an intensely heated condition. 
 Sometimes the ejected material is solid, and consists of 
 broken comminuted rock, or the so-called volcanic ashes. 
 Oftener, however, it is discharged in a more or less com- 
 pletely fused condition, constituting lava, which is s«Mne- 
 times fluid and glassy, but nior»i frisquently pasty and viscid, 
 so that it flows slowly and with difliculty. The ejected 
 
2 Volcanoes and Earthquakes. 
 
 matorials, whether Hquid or solid, build up volcanic cones 
 by successive layers — a fact which has been established by 
 modern observers in ijpposition to the notion come down 
 from antiquity, that volcanic hills are produced by an up- 
 rising or tumefaction of jueviously horizontal layers of rock 
 by the action of a force from beneath. First among the 
 gaseous products of volcanoes is watery vapor ; water ap- 
 pears not only to be involved in all volcanic eruptions, but to 
 be Ultimately combined witli the lavas, to which, as Scrope 
 has shown, it helps to give licpiidity. The water at this high 
 temperature is retained in combination mider great pressm-e 
 but as this pressure is removed i)asses into the state of va- 
 por, a process which explains the swelling up of lavas and 
 their rise in the craters of the volcanoes. Besides watery 
 vapor, carbonic and hydiochloric acid gases, and hydrogen, 
 both free and combined with sulphur and with carbon, are 
 products of volcanoes. The combustion of the inflammable 
 gases in contact with aii' sometimes gives rise to true burning 
 mountains — a name which does not pro])erly belong to such 
 as give out only acid gases, steam, and incandescent rocky 
 matters, which are incombustible. The escape of elastic 
 fluids from lavas gives to them a cellular stnictm'e, but when 
 slowly cooled under pressure, as seen in the dykes traversing 
 the flanks of volcanoes, the stony materials assume a more 
 solid and crystalline condition, and resemble the older erup- 
 tive rocks ftmnd in regions not now volcanic. These in(3lude 
 granites, trachytes, dolerites, basalts, etc., and are masses of 
 rock which, though extravasated after the manner of lavas, 
 became consolidated in the midst of surrounding rocks, and 
 consequently under considerable pressure. Their presence 
 marks either the lower portions of volcanoes whose cones 
 have been removed by denudation, or outbursts of liquefled 
 rock whicli never reached the surface. The escape of such 
 matters, and the formation of volcanic vents, are but ac- 
 cidents in the history of the igneous action going on beneath 
 the earth's surface. We shall, therefore, regard the extrava- 
 sation of igneous matter, whether as lava or ashes at the 
 surface, or as plutonic rock in the midst of strata, as, in its 
 wider sense, a manifestation of vulcanicity, and iV)r the elu- 
 cidation of our subject consider both those regions charac- 
 terized by great outbursts of phittmic rock in former geologic 
 periods, ami tliose now the seats of volcanic activity, which, 
 in these cases, can generally be trac(Mi back some distance 
 into tlie tertiary epoch. To begin with the latter, the first 
 and most important is the great continental region which 
 
Volcw}joe(i and Earihquah'H. ^ 3 
 
 may be deHcribod as including the Mediterranean and A.ralo 
 Caspian baHina, extending fr(im the Iberian peninsula east- 
 ward to the Thian-Chan Mountains of Central Asia. In 
 this great belt, extending over about 90*^ of longitude, are 
 included all the historic volcanoes of the ancient world, to 
 which we must add the extinct volcanoes of Murcia, Catalo- 
 nia, Auvergne, the Vivarais, the Eifel, Hungary, etc., some 
 of which have probably been active during the liumanpenod. 
 
 It is a most significant fact that this region is nearly coex- 
 tensive with that oecupi(Hl for ages by the great civiliznig 
 races of the world. From the plateau of central Asia, 
 throughout their westward migration to the j)illars of Her- 
 cules, the Indo European nations w(^re familiar with the 
 volcano and the earthquake ; and that the Semitic race were 
 not strangers to the same phenomena, the whole poetic 
 imagery of the Hebrew Scriptures bears ample evidence. In 
 the language of their writers, the mountains are molten, they 
 quake and fall down at the presence of the Deity, when the 
 melting fire buraeth. The fury of his wrath is poured forth 
 like fire ; he toucheth the hills and they smoke, while fire 
 and sulphur come down to destroy the doomed cities of the 
 plain, whose foundatitm is a molten flood. Not less does the 
 poetry and the mythology of Greece and of Rome bear the 
 impress of the nether realm of fire in which the volcano and 
 the earthquake have their seat, and their influence is conspic- 
 uous throughout the imaginative literature and the religi()us 
 systems of the Indo-European nations, whose contact with 
 these terri])le manifestations of unseen forces beyond their 
 foresight or control, could not fail to act strongly on their 
 moral and irttellectual development, which would have doubt- 
 less presented very ditterent phases had the earl;y^ home of 
 these races been the Australian or the eastern side of the 
 American continent, where volcanoes are unknown, and the 
 earthquake is scarcely felt.* 
 
 Besides the great region just indicated, must be mentioned 
 that of our own Pacific slope, from Fuegia to Aliaska, from 
 
 • Compare the fine lines of Pope, in the Essay on Man, where, of supersti- 
 tion, the poet siiys : 
 
 " She, 'mid the li^'htniug's glare, the thundev'B houucI, 
 While ro(!ke(l the earthquake, ami while rolled the ground, 
 She taught the proud to l>eiid, the weak to pray - 
 To Powers unseen and niijjfhtier far than they, 
 She, 'mid the rending earth and bursting skies, 
 Saw gods deseeiid aud fiends infernal rise ; 
 Here ti.ved the balefvd, there the blest abodes- 
 Fear ma<le her Aasilii aud weak hope her gods," 
 
Volcanoes itnd LhrUiqiiaketi. 
 
 whence along tlie oast<^ru shore of Asia, a hno of volcanio 
 activity extends to the terrible burning mountains of the 
 Indian archipelago. Volcanic islands are widely scattered 
 over the Pacific ])asin, and volcanoes burn amidst the thick- 
 ribbed ice of the Antartic continent. The Atlantic area is 
 in like manner marked by volcanic islands from Jan Mayen 
 and Iceland, to the Canaries, the Azores, and the Caribl)ean 
 islands, and southward to Ascension, St. Helena, and Tristan 
 d'Acunha. 
 
 The continents, with the exception of the two areas 
 already defined, present no evidences of modern volcanic 
 action, and the regions of ancient volcanic activity, as shown 
 by the presence of great outbursts of eniptive rocks, are not 
 less limited and circumscril)ed. In northern Eur( pe, the 
 chain of the Urals, an area in central Germany, and one in 
 the British islands are aY)parent, and in Nortli America there 
 appear to have been but two volcanic regions in the paleo- 
 zoic period — one in the basin of Lake Superior, and another, 
 which may be descril)ed as occurring along either side of the 
 Apallachian chain to the north-east, including the valleys of 
 the lower St. Lawrence, Lake Champlain, the Hudson and 
 Connecticut rivers, and extending still farther southward. 
 The study of the various eru])tive rocks of this region shows 
 that volcanic activity in different parts of it was prolonged 
 from the beginning of the paleozoic period till after its 
 close. 
 
 Having thus before us the principal facts in the history of 
 volcanoes, we may proceed to notice the various theories 
 from time to time put forward to account for them. The first 
 and most obvious notion is that of combustion, and we find 
 early writers supposing tbat volcanoes might be due to the 
 bumi^ig of coal, bitumen, or sulphur. As juster ideas were 
 acquired of the nature of combustion, and the necessity of a 
 supply of air for its maintenance, other chemical agencies 
 were invoked as the, probable source of intei'nal fire. Lem- 
 ery suggested the oxidation of siilphurets in the presence of 
 water, and the brilliant discovery by Davy, in the eartlis and 
 alkalies, of metallic bases which decompose water with great 
 violence, and even with the phenomena of combustion, gave 
 rise to the so-called chemical theory of volcanoes, which has 
 found its defenders down to our own time. This theory 
 supposes that the interior of the globe consists of the 
 metallic bases of earths and alkalies, which are oxidized by 
 the gradual access of the ocean's water, with the production 
 of intense heat, causing the fusion of the resulting oxides, 
 
VdvamH-s ami Earihqimkm. 
 
 which constitute hivas and oru])tive rocks. The chemical 
 objtictious which may be urged against this theory, are nu- 
 merous, and to my mind insuperable ; in addition to which 
 it may be added that it fails to explain the facts connected 
 with the ])ast and present distribution of vohMinoes, and is 
 in disaccord with tht)se vitsws of the early condition of the 
 globe most in harmony with the deductions t)f modern astnm- 
 ouiy, physics, and chemistiy. 
 
 I u(H)d not here re])eat the arguments in favor of the 
 theory which supposes our earth to be a cooling globe, which 
 has passed through various stages, fi-om an uncondensed 
 nebulous mass to a liquid, and finally to its present solid con- 
 dition, with a cold exterior ; nor to the evidences of a regularly 
 increasing temperature as we descend into its crust, from 
 which it is concluded that at a depth of a few miles a heat of 
 ignition would be attained. If we suppose the solidification 
 of the once liquid globe to have begun at the surface, which 
 became thus covered with a feebly conducting crust, it would 
 not be difiicult to admit, as some imagine, a still liquid 
 centre, surrounded by a shell of congealed matter upon 
 which are spread the sedimentary strata. Various and in- 
 dependent arguments from the j)henomena of precession, from 
 the theory of the tides, and from the crushing weight of 
 mountain masses like the Himmahiyah, have, however, been 
 brought against this liypothesis of a thin crust resting upon 
 a liquid centre, and in addition to these another important 
 one of a different order. Judging from the known proper- 
 ties of the rocks with which we are acqainted, solidification 
 should commence not at the surface, but at the centre of the 
 liquid globe, a process which would moreover be favored by 
 the influence of pressure. This augments the melting tem- 
 perature of matters which, like the rocks and most other 
 solids, become less defuse when melted, while on the other 
 hand it reduces the melting point of those which, like ice, 
 become more dense by fusion. Pressure, moreover, it may 
 be mentioned in this connection, increases the solvent power 
 of water for most bodies, whose solution may be describ- 
 ed as a kind of melting dow^n with water into a compound 
 whose densitv is greater than that of the mean of its consti- 
 tuents ; the nnportance of this point will appear farther on. 
 The theory deduced from the above considerations, and 
 adopted by Hopkins and by Hcropo, is briefly as follows : the 
 earth's centre is solid, though still retaining nearly the high 
 temperature at which it became solid. At an advanced stage in 
 the solidifying process the remaining envelope of fused matter 
 
6 
 
 VfilaimH.s iinti h'mthoiKth'S. 
 
 bocamo viscid, m^ thfit tlio descofit horn tho surfaco of tlio 
 htiiivior parti(!lea, cooled ])y radiation, was [)rov('nted, and a 
 cmst formed, tlirouf;;h which cooling has since gone on very 
 slowly. Tlu^re were thiiH left lietween this crust and tho solid 
 nucleus, portions of yet unsolidified matter (or even perhaps, 
 as suggested by Scrope, a continuous slieet), and it is in 
 tho existence of this stratum, or of lakes of um-ongealed 
 matter, that we are to tind an explanation of all the phenom- 
 ena of volcanoes and eartlniuakes, of (elevation and subsi- 
 dence, and of tlu^ movements whi(5h result in the formation 
 of mountain chains, as ingeniously set forth by Mr. Hhaler. 
 Tlie slow c<mtraction of th«^ gra(hially (tooling glol)o, a nu)8t 
 important agency in the latter phenomena, is evidently 
 not <>xcludod by this hypothesis. It may be added 
 that a similar structure of tho globe, viz., a solid nucleus 
 and a solid crust separated from each other by a litpiid 
 stratum, was long ago suggested by Halley in order 
 to explain the })henomena of terrestrial magnetism. Scrope 
 has con)])leted this hypothesis l)y the suggestion that varia- 
 tions in tension or piessure may cause portions of matter 
 beneath the surface tf) pass from solid to liquid, or from a 
 liquid to a solid state, and in this way help us to explain 
 the local and tlie temporary nature of volcanic activity. 
 
 This theory of Hopkins and Scrope, appa)ently so com- 
 plete in itself, is an approximation to the oiuj which I adopt, 
 though differing from it in some most important particulars. 
 While admitting with them the existence of a solid nucleus 
 and a solid crust, with an interposed stratum of semi-liquid 
 matter, I consider this last to be, not a [)ortion of the yet 
 unsolidified igneous matter, but a layer of material which was 
 once solid, but is now rendered liquid by the intervention of 
 water under the intluence of heat and pressure. Wh«!n, in 
 the process of refrigeration, the globe had reached the Y)oint 
 imagined by Hopkins, where a solid crust was formed over 
 the shallow molten layer which covered the solid nu(^lous, 
 the farther cooling and contratiion of this crust would result 
 in irregular movements, breaking it up, and causing the extra- 
 vasation of the yet liquid portions confined beneath. When 
 at length the reductioii oi Lemjierature permitted the precip- 
 itation of water from the dense primeval atmosphere, the 
 whole cooling and 'lisintegrating mass of broken-up crust 
 and pom-ed-out igneous rock would become exposed to the 
 action of air and water. In this way the solid nucleus of 
 igneous rock became surrounded with a deep layer of disinte- 
 grated and water-impregnated material, the rains of its 
 
k 
 
Volcanoes and EarUiquah'S. 
 
 7 
 
 former envcloi)e, and the ohaotio maHH from which, under 
 the influence of heat from below and of air and water from 
 above, the world of geologic and of human history waw to be 
 evolved. 
 
 As we descend in the Hedimeutary crust of the earth, we 
 observe a regular increase of temperature, due, as is sup- 
 poHed, to the slow upward passage of the (central ht^at. In 
 tlie present stattj of rcfrigt^'atiou this process is so slow that 
 tlie uicrease of ttimperatui'e in descending is only about (me 
 degree Centigrade for each hundred f(>et ; but if w(i adiuit 
 the hypothesis of a (tooling globe, it can be shown that in 
 early geologic ages this increase must have been tenfold, or 
 even twtjnty-fold greater than at present. As this augmenta- 
 tion of tempi^ratuie in depth obeys the same law alikii in the 
 newest and thf* oldest formations, it follows that the accumu- 
 lation of sedinn)ut at any time and place will resiUt in a slow 
 rise in temperature of the portion covered thereby, so that 
 a de])osit of a few miles in thickness in comparatively recent 
 ages, and probably one of as many thousands of feet in the 
 Laurentian or even the paleo/oic perio<l, would, after a lai)se 
 of time, so elevate the temperature of the buried portions as 
 to produce new chemical and mechanical arrangements of 
 the sediments. The expansive acti(jn of lieat u[)(m these 
 porous materials, which geiierally include several hundredths 
 of water, would soon be counteracted by the great contrac- 
 tion following chemical (;ombination, resulting in the forma- 
 tion of n<!W and denser com])ounds, which constitute the 
 crystalline, and nuitamorphic rocks, Tiio actitm of silicic ms 
 matters in the presence of water, aided by heat, upon the 
 vaiious (!arbonates, chlorides, sulphates, and organic mattera 
 which abound in most sedimentary formations, would gene- 
 rate the acid gases which are so often evolved in volcanic 
 eruptions. It must be borne in mind that water under 
 pressure, and at high temperatures, develops extraordinary 
 solv(!nt powers ; wliile from what has already been said of 
 the iniluenct) of pressuie in favoring solution, it will be seen 
 that the weight of the overlying mass becomes an efticitmt 
 cause of the liquefaction of the lowc.r portions of the sedi- 
 mtmtary material. Time is wanting to discuss the great 
 forces wliicli from early geologic periods hiive been active in 
 transferiing sediments, alteriuitely wasting and building up 
 continents. By the depression of the yiekdng crust beneath 
 regions of great accumulation there follows a softening of 
 the lower and of the mt)re fusible strata, while the great 
 mass of more silicious rocks becomes cemented into com- 
 
^ 
 
 8 
 
 Vokanoi'8 and Earthqnakef^. 
 
 parative rigidity, and finally, as the rosnlt of the earth's con- 
 traction, risoH a hardened and corrugated mass, from whose 
 irregular erosion results a mountainous region. 
 
 Those strata, whi<;h from their composition yield under 
 these conditions the most liquid products, are, it is conceived, 
 the source of all ])hitonic and volcanic rocks. Accom])anied 
 by Avater, and hy liifficultly (soeroible gases, thev are eitlier 
 extravasated among the tissurt^s which form in the overlying 
 strata, or find their way to the surface. The variations in the 
 compositi<^)n of lavas and their accom|)auying gases in dif- 
 ferent regions, and even from the same vent at different 
 times, are strong ccmfirmations of the truth of this view, to 
 which may be added tlie fact that all the various types of 
 lava are riipresen ted among aqueous sedimentary rocks, wln'ch 
 are capable of yieldiug these lavas by the process of fusion. 
 
 Th(> intervention of water in all lavas, of which it appears to 
 form an integral })art, was first insisted u])on by Scrope, and 
 is a fact hardly explicable upon any other liyjx (thesis than 
 th(! one just set forth. Considering the (renditions of its forma- 
 tion, water would seem to be necessarily absent from the <uigi- 
 nally fused globe, in which the older school of geologists con- 
 ceive volcanic rocks to have their source. S'^heerer su]>ple- 
 mented Bcrope's view by showing that the presence of a f(jw 
 hundredths of water, maintained under pressure at a tem- 
 perature approaching ignition, would probably suffice to pro- 
 duce a c^uasi-solution or an igneo-aquetms fusion of most crys- 
 talline rocks, and subsecpient observation of Sorby have 
 demonstrated that the softening and crystallization oi many 
 granites and trachytes must hav«^tak(m place in the piesenco 
 of wat(!r, and at temperatures not al)ov(^ a low red heat. 
 Keeping in view these facts, we can readily understand how 
 the shv^et of water-impregnated debris, which, as we have 
 endeavoi'ed to show, must have formed the envelopo to th(< 
 solid nuchms, assumed in its lower porti(m a semi-tluid ccm- 
 dition, and constitute*! a pi.istic bed on which i\iv> stratified 
 sediments repose. These, which are in part modified por- 
 tions of the disintegrated primitive crust, and in part of 
 chemical origin, by their irn^gular distril)ution over diffcu'ont 
 portions of the earth, determine, after a. lapse of time, in the 
 regions of their greatest ac(!umulation, volcanic pnd plntoniii 
 j)henome!ia. It now rinuains to show tlu» observed r«5lati(ms 
 of tliese phenomena, both in earlier and later times, to great 
 accumulations of sediment. 
 
 If we look at the NoHh American continent, wo. tind along 
 its north-eastern portion evidences of great subsidence, and 
 
Volcanoes ami Earthquakes. 
 
 9 
 
 an acounmlation of not less than 40,000 feet of aodiment 
 along the line of the Appalachians from the (lulf of St. Law- 
 rence southwards, during the paleozoic ^jeriod, and chiefly, it 
 would appear, diu-ing its t^arlier and later portions. This re- 
 gion is prcHrisely that characterized by considerable eruptions 
 of plutonic rocks during this period and for some time after 
 its close. To the westward of the Appalachians, the deposits 
 of ])aleo/oic sediments were much thinner, and in the Mis- 
 sissippi valley are [)r(>l)ably less than 4,000 feet in thickness. 
 Conformably with this, there are no traces oi plutonic or vol- 
 canic outbiu'sts fiom the north-east region iust mentioned 
 tliroughout this vast paleozoic basin, with the exception of 
 the region of Lake Superior, where we find the eariy poi-tion 
 of the paleozoic age marked hy a great accumulation of sed- 
 iments, comparable to that occurring at the same time in the 
 region of New England, and followed or accompanied by 
 similar plutonic phenomena. Across the plains oi northern 
 Russia and Scandinavia, as in the Mississippi valley, the 
 paleozoic period was represented by not more than 2,000 feet 
 of sediments, which still lie undisturbed, while hi the British 
 islands 60,000 feet of paleozoic strata, contort(xl and accom- 
 panied by igneous rocks, attest the connecticm between great 
 accumulation and plutt)nic phenomena. 
 
 Comhig now to modern volcanoes, we find them in theii* 
 greatest activity in oceanic regions, where subsidence and 
 accumulation are still going on. Of tlu; two continental re- 
 gions already ])ointed out, tliat along the Meiiiterranean 
 basin is marked by an accumulation of mesozoic and tertiary 
 sediments, 20,000 feet or more in thickness. It is evident 
 that the great mountahi zone, which includes the Pyrenet^s, 
 the Alps, tlie Caucaims and the Himmalayah, was, during 
 the later secondary and tertiary periods, a basm in wliich 
 vast accumulations of sediments were taking piact^ as in the 
 Appalachian belt during the paleozoic times, l^irning now to 
 the other contintuital region, the American Pacific slope, sim- 
 ilar evidences of great ac(!umulations during the same periods 
 are found throughout its whole extent, showing that the 
 great Pacific mountain belt of North and South America, 
 with its attendant voltianoes, is, in the main, the geological 
 eijuivalent or counterpart of the great cast and west belt of 
 the eastern world. 
 
 It is to be remarked that the volcanic vents are seldom 
 immediately along the lines of greatest accumulation, but 
 appear around and at ceriain distances therefrom. The 
 question of the duration of volcanic activity in a given re- 
 
10 
 
 Volcanoes and Earthquakes. 
 
 gion is one of great interest, which cannot, for want of time, 
 e considered here. It appears probable that the great 
 manifestations of volcanic force belong to the period of de- 
 pression of the area of sedimentation, if we may judge from 
 the energy and copiousness of the eruptions of island volca- 
 noes, although the activity is still prolonged after the period 
 of elevation. 
 
 As regards the geological importance of volcanic and 
 earthquake ])henomena, their significance is but local and 
 accidental. Volcanoes and earthquakes are and always have 
 been confined to limited areas of the earth's surface, and thp 
 products of volcanic action make uj) but a small portion of 
 the solid crust of the globe. Great mountains and mountain 
 chains are n )t volcanic in their nature or their origin, though 
 sometimes crowned by volcanic cones ; nor are earthquakes 
 and volcanoes to be looked upon as anything more than inci- 
 dental attendants upon the great agencies which are slowly 
 but constantly raising and depressing continents. 
 
 Tlie theory of volcanic phenomena here set forth was first 
 partially indicated by Keferstein in 1834, and subsequently 
 and apparently independently by Sir John Herschel in 1837. 
 It, however, attracted little or no attention until, in 1858 and 
 1859, I again brought it forward, and endeavored to show 
 its conformity with the facts of chemistry, jiliysics, and 
 geognosy. In the hasty sketcli of it here given, t-.ie chemist, 
 the geologist, and the geogra])her will alike discover points 
 which require elucidation or provoke criticism, but will, I 
 hope, find, nevertheless, a concise and intelligible statement 
 of a theory of earthquakes and volcanoes which appears to 
 me more in harmony with the known facts of science than 
 any other hitherto advanced. 
 
 P. S. — In justice to myself, it should be said that at the 
 the time this lecture was delivered I had no knowledge of 
 Prof. J. D. Whitney's excellent and suggestive paper on 
 earthquakes, which appears in The North American lieview 
 for April, 1869. The relation of modern volcanic phenomena 
 to great accumulations of newer secondary and tertiary rocks, 
 and the connection of the foldings and contortions of sedi- 
 mentary strata with great thicknesses of the same, are set 
 forth by me in several papers, the chief of which may be 
 found in the Canadian Journal for May, 1858, the Oedogical 
 Journal for November, 1859, and the American Journal of 
 Science for July, 1860 (vol. xxx., p. 1 38), and also for May, 
 1861 (vol. xxxi., pages 406-414), where tlie important contri- 
 butions of Professor James Hall, bearing upon this question, 
 are noticed at length. T. S. H.