«F ■^.. IMAGE EVALUATION TEST TARGET (MT-3) ^/ „* **>^ .•v^^ ^^n^>^ ^o 1.0 I.I ■30 ~^^ ■■■ ■^ 1^ 12.2 Ilm |L25||U,,.6 ^ 6" ► ^ '^ ^>. ^^^'^^ /1 Photographic ^Sciences Corporation ',!3 WES\ MAIN STREET WEBSTER, N.Y. I4S80 (716) S79 4503 V iV jd^ < *^*'*^'^^*^ ^Olr^^: J.Uurra// ^ilboruxrle/ Street, ^^^rryyt^^u^ZZmc />/ yyi/reii -finyOtii'^ EXCERI'T I-K03I THK JoURNAL Ax\D PkOCKEDINGS OK THE ROYAL GKOGRAPMICAL SOCIKTV, 1, Saviik Rr)„v; FRANCIS EDWARDS, 85, IIicn Stkkkt, Maryi.kdonk, W. 49 r . Cook oi'Woodv Cin„^^'^\^^,^^ MAP OF and part of BRITISH COLUMBIA to accompany the Paper by R. Brown, Esq^" f^iig'lish Miles o 10 io Geotfi-aphical Miles 10 io 4o flo l'J7 12 (> N«c«*^ .V'* ^^ ^.cvf \^\mAM Barclay •=> ^^^ve^V ^(^ 4^ .^ Bo^*" Vo C.Clasi let or Flattmy^; /^tUiUs/ii.i rir rJit ti: ♦ The late Professor Edward Hitchcock, of Amherst, U. S. America, has published a memoir " On the Erosions of the Earth's Surface, especially by Rivers," in ' The Smithsonian Contributions to Knowledge,' vol. ix. ; but this treatise I am unable, in the place where this paper is written, to refer to, — a matter which I the more regret as I am convinced, from a familiar acquaintance with many of the venerable author's other researches, that it must contain many strikingly original observations. 126 Brown on the Formation of Fjords, Canons, Benches, These broadly marked " benches " ought not to be confounded with some terraces found on various rivers, such as the Columbia, &c., to the west of the Cascades. These terraces are probably connected with glacier action A^hen the mouth of that river was hollowed for more than a hundred miles of a great and uniform depth. The channel of the Golden Gate (San Francisco) has a maximum depth of nearly 50 fathoms, being greatest imme- diately in the line of the axis of the chain, through which it is cut, while the bar without, and the bay within, are silted up to within less than 10 fathoms of the surface. The straits of Car- quines, near the mouth of the Sacramento, have a maximum depth of 18 fathoms, and in the line of the range which bounds them an average depth of 14. Dr. Newberry* thinks that these phenomena are due to glacier action of a similar charac- ter to that which hollowed out the fjords ; and on the whole there seems some reason to accept his theory, with reserva- tions. In passing down the Columbia from the Dalles (Lat. 45° 35' 55 N., Long. 120° 55' w.) to the Cascades, a curious feature is seen, which though scarcely strictly coming under any of the headings of this paper, is yet interesting, as help- ing to explain some of the phenomena of bench and caiion. Under the water can be seen, standing upright and firmly rooted in the soil, the remains of a forest of Ahies Douglasii (Lindl.). General Fremont noticed this in his voyage down the river, and attributed it to a landslip. This explanation may be easily proved to be erroneous, and must, I think, though gene- rally received without investigation, give way to a totally different one. The vicinity of the Cascade exhibits marks of recent volcanic action and disturbance of the traps. The Indians even say that, at one time, the river used to flow under an archway, but that during an eruption of Mount Adams this bridge was thrown down, forming an island in the centre, and helping to give rise to the " Cascades." The effect of this would be to form a dam in the water, raising its waters above the scene of disturbance, and submerging the forest which grew down to its margin. The very recent date of this sub- mergence is shown by the sound character of the wood. The " bench " is also well figured in the plate of the Caiion of Psuc- see-que Creek (Oregon) in volume yi. p. 85 of the * Pacific Eailroad Surveys.' f 4. Prairies. — The central portion of the American continent, as indeed of Asia and Africa (witness the great " Steppes " and the " Sahara ") is almost treeless, and with a correspondingly * * Pacific Railroad Surveys,' vol. vi. p. 43. t On this subject, see also Hector, in the ' Quarterly Journal of the Geological Society,' 1863, p. 399. Prairies, and Intermittent Rivers. 127 small rainfall. The Cascades and tlie Rocky Mountains pre- vent the moisture-laden breezes of the Pacific from reucning the tracts under their special influence, and the distance of great prairies from the sea-board of the Atlantic, renders the moist wind of little influence before reaching the country over which the great " plains " extend. East of the Mississippi the rainfall is greater, and here we have an almost unbroken forest. Between the Cascades and the Rocky Mountains, for the same reason, trees are scarce and the climate dry ; so much so, that some portions of the country are little better than desert, while immediately to the west of the former range, the slopes of the mountains are covered with luxuriant forest and fertile soil. Along the line where the treeless and forest districts meet, local causes determine the presence or absence of trees. Belts of timber border the streams, and cover the more porous and absorbent soils, while level surfaces, with fine and unporous soils, sometimes very wet, and sometimes very dry, sustain only a growth of grass, which could endure the alternations fatal to trees. Annual fires have had their influence in extending the area of grassy surface, and over much of their middle ground, by man's intervention, the causes limiting the growth of trees could be removed, and the forest area extended. The forces of nature are here so nicely balanced, that slight causes would make one or the other preponderate. The many theories which attribute prairies to other causes than the want of water are wholly erroneous, and of only local value. On the great prairies west of the Mississippi, every variety of soil and surface fails to sustain trees, and only a change of climatic conditions will there change the grass-covered surface to forest.* It would, however, be generalising on very imperfect data were we to conclude that all grassy land known vaguely under the term " prairie," was formed under the same conditions ; for to the west of the Cascades are also prairies of some extent, due to totally different causes. These West of the Cascade " Prairies" may be shortly enumerated under three heads : — (1.) " Tide lands " overflowed by the tide only at its highest periods, and of excellent soil. These are almost invariably found at the mouth of rivers, and the absence of trees upon them is due to the overflow by salt water, or the coldness of the mountain flood, which must sap the roots of deeply growing plants like trees. (2.) Other small prairies are found along the sources of rivers, particularly mountains always marshy from springs, and ♦ J. S. Newberry, ♦' On the Origin of Prairies," ' Transactions of the American Scientific Association,' 1866 (BuflFalo Meeting), and Foster's ' Mississippi Valley.* 128 Brown on the jcormation of Fjords^ Canons, Benches, producing a growth of plants almost identical with those at 5000 feet on the mountains of North- West America or on the northern regions of Europe and America. The "Cranberry swamps " are of this nature. (3.) Dry prairies — with rich black vegetable loam — said to be sometimes too rich for wheat. On Whidby's Island and other places on De Fucas Straits, such as Orcas and San Juan Islands, are prairies of this description, which though now high above water, appear to have been formed of a deposit from some river when the distribution of land and water was different from what it is now. The Nisqually plains, the Great Willamette Prairie, &c, are examples. They are generally thinly scattered with oak (Quercus Garryanus), and with a very characteristic group of plants, rarely or never found out of such tracts. Often scattered with lakes and clumps of trees, their park-like cha- racter has been frequently noticed and admired.* A modifica- tion of this, or perhaps rather of the tide lands, is seen in strips of sand, grass lands covered with coarse grass found at various places along the coast, and distinguished by such plants as Ahronia arenaria, A. umheUata, Orohus littoralis, Franseria, Calystegia, &c. These dry prairies are scattered through the forest land, such as the Squak Prairie, near Seattle, in Washington Territory, and even the Willamette Prairie in Oregon must bo classed as of this nature. The Comox Prairie in Vancouver Island, the Cowichan Prairies in the same island, &c., are also of a similar character. What strikes one particularly is the abruptness with which the forest ends, giving these prairies almost the appearance of "clearings" in the forest. They can certainly be produced by no climatic or terrestrial peculiarities, as the neighbouring forest is sub- ject to influences iu every respect the same. I quite agree with Dr. Cooper, to whose excellent work on the ' Natural History of Washington Territory ' I have been much indebted, that these prairies bear the mark of having been at one time much greater, and that they have been to a great extent pro- duced by burning, either through the Indians, or by the forests catching fire. I know that in various places the forest is now covering tracts which within the memory of man were grassy prairies on which the Indians grazed their horses ; and on the Nisqually prairies, only as far back as 1847, several seamen and officers of one of H.B.M.'s vessels, then lying in Puget Sound, were buried on the prairie. Their graves are now in a dense % ill • Wilkes, * Exploring Expedition ;* Lord, * Naturalist in British Columbia,' and in * Temple Bar,' Oct., 186tj; Suckley and Cooper, ' Nat. Hist. Washington Terri- tory,' &c. Prairies, and Intermittent Rivers. 129 thicket of trees. Other prairies, such as most of the Willamette Prairies, appear never to have been covered by forest, and great changes seem to have occurred since these were formed. Several species of animals if not confined to the prairies are yet quite characteristic of them, such as the gopher (Thomomys Dougrlasii, Rich.), meadow mice {Jaculus Hudsonius, Zimm.), sewellel {Ajplodontia leporina, Rich.), and the prairie mole (Hesperomys austeru», Baird). These animals are principally seen on the Nisqually prairie, and seem, like certain plants found there, to have wandered from the east of the mountains.* On some of these prairies are peculiar mounds of gravel and soil, which appear to have been produced by some tidal influ- ence when these prairies were covered by the sea. The whole subject of the formation of Western prairies is very interesting, but would lead me into discussion foreign to my subject, so that I can only touch on what would require a volume specially to treat of.f In connection with this subject, I may mention that in Southern Oregon and other parts, the south side of a hill is generally bare, while the north is covered with vegetation, a fact taken advan- tage of by the Indian skirmisher. 5. Intermittent Rivers. — All the great rivers of North- West America rise either in the Rocky Mountains or in some of its tributary spurs, and though the Cascade Range gives various tributaries to the rivers which flow into the Pacific, none of them, with the exception of the Willamette, Rogue River, Chehalis, and some smaller streams, have their source in the Cascade Range : , indeed the former unites with the larger Columbia, and under that name reaches the ocean. Only one river of the slightest consequence rises on the eastern or arid side of the mountains, viz., the Deschutes, which, after keeping along near the base of the mountains, dashing over falls and between high rocky walls, joins the Columbia just above the "Dalles" of the latter river. Some indeed (like tlie Klamath) take their rise in lakes, fed by streams from the mountains, and gathering strength find their way to the Pacific through some of the broken portions of the chain immediately south of the 42nd parallel of north latitude. It is only the great rivers such as tlie Columbia, which gather- * Cooper, loc. cit. t I have described these Western Prairies, and other points in the physical geography of North- West America, more fully in a memoir entitled " Das Innere der Vancouver Insel " (Peterman's 'Geographische Mittheilungen,' Heftes i.-iii. 1869), in a paper "On the Geographical Distribution of the Coniferoe and Gnetaceae" ('Trans. Botanical Society, Edinburgh,' vol. x. p. 175); in another, " On the Geographical Distribution and Physical Characteristics of the Coal Fields of North- West America " (• Trans. Edin. Geological Society,' 18(i8-9), in an official report of my 'Explorations in Vancouver Island' in 18«4 (Victoria, V, I., mtifi), and in a separate i/rork now publishing, entitled ' Hone Sylvauo:.' VOL. XXXIX. K 130 Brown on the Formation of Fjords, Canons^ Benches, ing tributaries on every hand, such as the Snake (the Saptin or Lewis River of the older travellers), the Kootane, the Flathead, &c., can muster strength to cross the " great desert " or " basin," and reach the ocean in triumph. The smaller ones are less fortunate and are swallowed up in this Sahara of the west, gradu- ally lessening and lessening until they are lost in the sand. Such are the " sinks " of Carsons and Humboldt rivers to the south. Sometimes these rivers rise and sink several times in the course of a few miles, and their course can only be laid down by alternate dotted and " full " lines. At least we suppose them to be the same river, for in this strange cavernous region another curious phenomenon presents itself, viz., that of small rivers springing cold and clear, like Minerva full armed from the brain of Jove, right from Mother earth, without undergoing any of the preliminary operations which their slow-going sisters suffer in older lands, but again, after describing a sullen course, making fertile some oasis in the desert, disappearing at once under the ground. An even still more curious feature presents itself in some of the creeks flowing from the snows of the Cascades ; down their eastern slope sometimes in the forenoon we would encamp by the side of a stream with but barely sufficient water for camp purposes, but on returning in the evening found it roaring and crashing along so full of water as to render the fording of it a matter of difficulty, and again in the morning would find it almost diy, with the marks of last night's flood visible on the wet sand and gravel. I see that General Marcy narrates a similar circumstance when exploring the Red River of the South,* but failed to account for it, though I believe that the explanation I am about to give will be found not very far from the truth. These streams head in high mountains, and the sun is not of sufficient power to melt the snow which jforms their volume until late in the day, when they gather force, and again decrease after sunset until they are almost dry. I have seen muleteers near the base of Mount Shasta (14,400 feet) in North California waiting for the rising of the creek, like the children of Israel for the smiting of the rock ; and it was some- times long after dark before the stream would be heard rushing down its former dry bed. So familiar was this phenomenon that sufficient water for breakfast would be saved over night, knowing that the creek would be almost dry before morning. In this paper, for the sake of conciseness, I have endeavoured to present the conclusions at which I have arrived rather than the data on which these deductions were founded. I trust, however, that I have to some extent presented sufficient facts to i * * Army Life on the Border' (1866), p. 135, ^.I Prairies, and Intermittent Rivers. 131 establish thepoints at which I have been aiming, viz : — 1. Fjords are in almost every case identical in formation, and were the beds of former glaciers. 2. Canons are formed by the action of river currents. 3. Benches are the marks of the successive levels of the river when in the form of a lake, and the successive levels are the results of the sudden breaking down of barriers tending eventually to form the present canons. 4. Prairies in the interior of America are due to the cause which renders arid the greater portion of the interior of conti- nents, viz., want of rains. 5. Intermittent Rivers are the result of the dryness of the great basin owing to the moist breezes of the Pacific being intercepted by the peaks of the Cascade Mountains, the melting of the snows, and other minor causes, and the " sinks " of rivers are due to these same causes (especially the drought), and the volcanic cavernous character of the country.