« PreviousContinue »
that region was left somewhat incomplete in consequence of a prolonged snow-storm.
As the Togwotee Pass some characteristic views were obtained of the remarkable breccia mountains, whose castellated forms adorn that portion of the continental divide, and also some of the curious "bad lands" farther down on Wind River. The season's work closed at Camp Brown, where some excellent portraits and groups were made of the Bannock prisoners in confinement at that post.
A brief summing up of the season's operations of three months, much of which time was characterized by extremely inclement weather, shows an increase to the already very extensive collection of the survey, of 45 negatives 11 by 14 inches in size, and 110 of smaller ones, 5 by 8. The number was purposely kept small that a better quality might prevail in them.
The geologist in charge accompanied the photographic division, and the route pursued gave him an opportunity to secure a very accurate general knowledge of the geological structure of a large area. The Wind River Range proved one of remarkable interest. It has a trend about northwest and southeast, with a length of about 100 miles. On the west side all the sedimentary belts have been swept away, down to the Archæan, older than the Wahsatch, and the latter formation rests on the Archæan rocks all along the base of the range, seldom inclining more than 50 to 100. On the east side of the range the seams of sedimentary formations usually known to occur in the northwest are exposed from the Potsdam sandstone, which rests upon the Archæan rocks, to the Cretaceous inclusive.
Along the northwestern portion of the range the Wahsatch Group only is seen for some distance, but as we proceed down the Wind River Valley the formations appear one after the other, until at the lower end the entire series is exposed. The Wind River Range may be regarded as originally a vast anticlinal, of which one side has been entirely denuded of the sedimentary, except the Middle Tertiary. On the same side of the range the morainal deposits and glaciated rocks are shown on a scale such as we have not known in any other portion of the West. Three genuine glaciers were discovered on the east base of Wind River and Frémont Peaks, the first known to exist east of the Pacific coast.
The morainal deposits are also found on a grand scale in the Snake River Valley, on the east side of the Teton Range. The numerous lakes have been the beds of glaciers, and the shores of the lakes are walled with morainal ridges. North of the Teton Mountains the prevailing rocks are of modern volcanic origin, and in the Yellowstone Park the hot springs and geysers are the later manifestations of the intense vol. canic activity that once existed. All these interesting features were studied with care, and the results will be elaborated for the twelfth annual report of the survey.
It was with great pleasure that the geologist in charge reviewed the ground passed over in 1860, over eighteen years previously. In the years 1859 and 1860 he acted as geologist to the exploring expedition under the command of Col. William F. Raynolds, now of the Engineer Corps, U. S. A. A portion of the geological report made on that expedition will be reprinted in the 11th annual report.* A geological map accompanies this report, which embraces Dakota and Montana, with portions of Idaho, Wyoming, and Colorado.
* Geological Report of the Exploration of the Yellowstone and Missouri Rivers, under the direction of Capt. (now Lieut. Col. and Brevet Brig. Gen.) W. F. Raynolds, Corps of Engineers, 1859-1860. By F. V. Hayden.
The publications of the survey during the past year have been numerous and important. The atlas of Colorado, in twenty sheets, has received the most unqualified praise for its accuracy and beauty, both in this country and in Europe. The following analysis of the atlas was written for the London periodical “Nature," of September 12, by Prof. Archibald Geikie, director of the geological survey of Scotland and professor of geology in the University of Edinburgh, and one of the ablest geol. ogists in Europe :
In the magnificent atlas just issued by the Department of the Interior we have the consummation and crown of all the labors which Dr. Hayden and his staff have carried on so triumphantly for the last five years, and of which they have already given us so inuch interesting and important information in a series of annual reports. Before examining the work from a scientific point of view, no reader can refrain from expressing his admiration of the style in which the atlas has been produced by the United States Government. As a specimen of cartography, typography, and lithography it is altogether worthy of the highest praise. For beauty and, indeed, sumptuousness of execution, it may be classed with those livres de luxe which from time to time have been issued from the National Imprimerie of France.
The atlas consists of two series of maps, the one of a general, the other of a detailed kind. The first series, on the scale of twelve miles to one inch, comprises four sheets, each embracing the whole State of Colorado and part of the neighboring territory. The first of these illustrates the system of triangulation adopted in the survey; the second shows the drainage system of the area; the third, by a simple and clear arrangement of colors, exhibits at a glance the economic features of the whole regionthe agricultural land, pasturage, forests and woodlands, sage and bad lands, mineral tracts, and the portions rising above the limit of timber-growth; the fourth contains a con• densed and generalized geological map of the same territory. Nothing can surpass the lucidity of expression and artistic finish of these maps.
The second series—twelve in number—is on the scale of four miles to one inch, and consists of six topographical sheets and six identical sheets, colored geologically. The topographical details, though numerous, are so selected as not to neutralize each other or mar the broad, clear picture which the maps were designed to be. By means of contour-lines of 200 feet vertical distance, the surface-configuration of the whole region is depicted as in a model. We can follow the lines of the broad valleys, of the deep, narrow cañons, and of the hundreds of minor tributaries which have scarped out their courses on either side. Here we look down upon a vast table-land, deeply trenched by stream-channels; there upon a succession of bold escarpments or mesas, which bound the table-land and hem in the neighboring valley. Huge mountain-ranges rising out of the plateaus are so vividly drawn that they seem to stand out of the paper; yet no shading is employed. All the effects of inequality are produced by contour lines, so faithfully set down that a single line may be tracked in its sinuous course along the whole of a mountain front until it comes out upon the table-land beyond. When will our map-makers learn to use this, the only true method for expressing the surface of a country! The best of our atlases are distigured by strips of shading running across the map, like so many caterpillars, to represent mountain ranges. Even our ordnance maps, so admirable in most respects, are sometimes so loaded with shading that a steep billside, only a few hundred feet high, is made as black as our highest mountains, and the topographical names can hardly be read, even with a magnifying-glass.
But, above all, welcome are these six geological maps. In the previously published maps and charts accompanying the annual reports only small detached areas were represented, and even from the careful descriptions of the various geologists of the staff, it was hardly possible to frame a satisfactory conception of the geology of Colorado as a whole. Ever since the marvels of its deep gorges and vividly painted cliffs were made known, that region bas possessed a high interest to the geologist. He has now the means of gratifying his desire for further knowledge. With the help of these maps and the two accompanying sheets of sections, he can realize most satisfactorily every great feature of Colorado geology. The ancient Archæan ridge-the nucleus or backbone of the American Continent-may be traced running north and south nearly along the present hydrographical axis of the country. Flanking that ridge comes a series of Palazoic deposits, the oldest of which have been identified palaontologically with Silurian formations. Rocks regarded as of Devonian age overlap the Silurian beds, and repose against the ancient crystalline ridge on the southwest side of the San Juan Mountains. They are soon buried under later accumulations, and they seem to be of but local development, since in most places where the rocks are found in juxtaposition, the Silurian are directly succeeded by Carboniferous strata. These last-named rocks cover large tracts of country, running as bands round the Archæan area, and lying in basins across it. Far to the west, where the Grand River has so deeply trenched the Utah plateau, the flat Carboniferous beds appear from under the brilliant red Triassic strata. The difficulty of drawing any line between Triassic and Jurassic formations in that region is again acknowledged on these maps, the lower red series being doubtfully assigned to the older, and the upper variegated deposits to the latter system.
Cretaceous rocks are abundantly developed, and cover a vast extent of territory. In particular, they spread over the wide plateaux between the San Juan and Gunnison Rivers, and form the platform on which the enormous volcanic outbursts have been piled up from the West Elk Mountains southward into New Mexico. It is more easy to trace on these maps, too, the area respectively occupied by the Laramie, Wasatch, Green River, Bridger, and Uintah formations which represent Post Cretaceous and Tertiary times. Glacier moraines, lake deposits, drifts, sand-dunes, and recent alluvia, all find adequate expression on the maps. Especial care, too, seems to have been bestowed upon the eruptive rocks which form so important and interesting a feature of Colorado geology. The more characteristic varieties are represented by distinct shades of crimson or orange, and they have been mapped in such a way as to convey at a glance, and even without the aid of sections, a tolerable clear notion of the volcanic phenomena of the region. On the one hand we see the great lava-sheets capping the mesas and spreading far over the plateaux; on the other, we notice the great centres of volcanic activity, with their abundant flows, dikes, and breccias.
Two sheets of sections, drawn across all the more interesting and important portions of the geology, complete the vast fund of information given by the maps; while, that nothing may be wanting to enable readers to realize what has been done by the survey, and the conditions under which it has been accomplished, two large sheets of sketches are given, which most vividly represent the forms of the monntains, plateaux, mesas, and river channels as seen from various commanding heights.
Dr. Hayden, with whose personal supervision this great work has been accomplished, has increased tenfold the obligations under which he has laid geologists all over the world for the number and value of his contributions to geology. He now furnishes us with new light whereby to read his former researches and those of his able colleagues. May we venture to hope that he may find leisure to confer yet one further benefit before the progress of his survey plunges him into a new whirl of work? If he could be prevailed upon to sketch out a plan for digesting the materials of his published annual reports, he could doubtless find among his staff some competent writer who, under his guidance, could produce a well-arranged systematic guide-book or text-book to complete the value of the work of his survey. Such a book of reference as would give a reader who has never had access to the annual reports a clear and comprehensive view of Colorado geology would be of great service.
These remarks may be fitly closed with an expression of the warmest admiration of the liberal spirit in which the United States Government has conducted these surveys of the Territories and has published their results. This costly atlas has been distributed gratuitously all over Europe. That this is a wise policy cannot be doubted. Whether actuated or not by a desire to diffuse scientific information, the authorities at Washington do well to make as widely known as possible the geological structure and economic resources of their country. They cast their bread upon the waters and the harvest comes to them in the form of eager, active emigrants from all parts of Europe.
The Bulletin of the Survey has now reached the close of the fourth volume, which contains 37 articles and about 900 octavo pages. The tenth annual report embraces 550 closely printed pages, octavo, with 80 plates, maps, sections, &c. About 50 of the plates illustrate the remarkable cliff-dwellings which were found by the members of the Survey along the cañons of the streams of Southern Colorado and New Mexico. Volume IV, quarto, on the Miocene and Pliocene vertebrates of the West, by E. D. Cope, and Volume XII, by Dr. Joseph Leidy, on the Rhizopods, are far advanced, and will be ready for distribution in the spring. The eleventh annual report is in press; about 300 pages already in type. This volume will be issued early in the spring.
The members of the Survey are now all in the office from their fieldwork, and busily engaged in elaborating their field-notes. The materials for the twelfth annual are very ample and of great interest. Very respectfully, your obedient servant,
F. V. HAYDEN,
United States Geologist, Hon. CARL SCHURZ,
Secretary of the Interior.
The following articles on the geology of the Rocky Mountain region were published in the American Journal of Science, New Haven, Conn., several years ago, and are now entirely out of print. Inasmuch as they contain some views that have either been absorbed or overlooked by modern geologists, they are reprinted in this connection. There are some views that, if written at this time, might be restricted or modified, but in the main they are correct. The articles are reprinted without any alteration.
SOME REMARKS IN REGARD TO THE PERIOD OF ELEVATION OF
THOSE RANGES OF THE ROCKY MOUNTAINS NEAR THE SOURCES OF THE MISSOURI RIVER AND ITS TRIBUTARIES.
(From the American Journal of Science, vol. xxxiii, May, 1862.) The object of the present article is to show, as nearly as can be done from known geological data, the period of the elevation of a portion of the Rocky Mountains. My observations have been more especially confined to the ranges from which the Missouri and Yellowstone Rivers, with their numerous tributaries, take their rise, though I feel confident that principles which will apply to mountains occupying so large an area will also be applicable to the whole Rocky Mountain district. It will be impossible, at this time, to mention in detail all the facts in support of my statements, and therefore I shall assume that the reader has examined the previous papers of my associate, Mr. Meek, and myself. During the coming year I hope to prepare a series of articles for this journal which will have a more or less direct bearing on the physical geography of this region and the influences which gave to it its present configuration. Some erroneous statements, growing out of our limited knowledge of the structure of these mountain chains, may be made, but these, when known, will be corrected. Geology is a progressive science, and even our best efforts are but approximations to truth rather than the truth itself.
• The evidence seems to me to be clear that the great subterranean forces that elevated the western portion of our continent were called into operation toward the close of the Cretaceous epoch, and that the gradual quiet rising continued, without a general bursting of the earth's crust, until after the accumulation of the Tertiary lignite deposits, or at least the greater part of them; also, that after the fracture of the surface commenced and those great crust movements began to display themselves, the wholo country continued rising, or at least, though there may bave been periods of subsidence or repose, there was a general upward tendency, which has continued even up to our present period. I hope hereafter to illustrate the correctness of these statements by all the facts that have been obtained in my past explorations as well as by those I may secure in the future.
Let us, in the first place, examine some of the barometrical profiles across the country from the Mississippi River to the Pacific coast, constructed under the direction of the War Department. Previously, however, to this examination we may make the statement that west of longitude 98° the surface of the country may be separated into two divisions, mountain and plain, and that a combination of the two compose the Rocky
* For most important information I would direct attention to second series of this journal, articles xiii, xxxix, vol. iii, 1847, article xxxiv, vol. xii, 1849, and articles xxiv, Xxv, vol. xxii, 1856, by Prof. J. D. Dana, in which, it seems to me, will be found the most profound, far-reaching generalizations in regard to the physical geography and geology of the West and other portions of our country which have ever been given to the public. The origin and character of those subterranean forces which have produced such important results in the West are fully discussed in those papers.
Mountain district. After leaving the Mississippi the intervening country westward to the upheaved ridges is an apparently level or undulating plain, with no disturbance of the strata of the underlying formations until we come in close proximity to some of the mountain elevations. Reaching the base of the elevated ridges which form the mountain crests, we at once commence a rugged and abrupt ascent.
If we look at the profile constructed by Governor Stevens, from Saint Paul, Minn., latitude 44° 58' and longitude 920 58', to the Pacific coast, we shall find that the starting point is 828 feet above the ocean-level. Near Fort Union, at the junction of the waters of the Yellowstone and Missouri, 670 miles westward, the height above the ocean-level has increased to 2,010 feet, or 1,182 feet higher than Saint Paul. We thus see that the average ascent of the country between these two points is not quite two feet to the mile. From Fort Union to the valley of Dearborn River, just under the base of the elevated ridges of the principal eastern range, we find the distance to be 448 miles and the height above the ocean 2,081 feet greater then that at Fort Union, or the average rate of ascent increased to nearly five feet per mile. Over this vast extent of country extends an almost limitless prairie, apparently level, with no forests or groves, with no timber except that which skirts the streams. There is in this great distance a gradual increase in the inclination of the strata proportioned to the increase of the ascent, but no marked disturbance of the beds until we arrive in close proximity to the mountain elevations. There are a few local fractures of the earth's crust caused by the elevation of the Bear's Paw, Little Rocky Mountain, &c., around which the sedimentary rocks are more or less disturbed, but all these lesser mountains are more or less remotely connected with the main chain. After passing the highest point of the principal range, along this line, which is near Cadotte's Pass, we commence our descent toward the Pacific very much as we ascended the eastern slope, but over a much more rugged route, We find a continued series of more or less parallel ridges of elevation until we approach the coast for a distance of from 400 to 600 miles. From Fort Walla Walla to the ocean, however, the average descent is a little less than one foot to the mile.
Again, if we examine the profile constructed by Frémont, commencing at the mouth of the Kansas River, we find that the initial point is 690 feet above the ocean. Proceeding westward, the average grade for the first 300 miles is between 4 and 5 feet per mile. "Thence to Fort Laramie the ascent, as stated by Frémont, is 8 feet to the mile, and from Fort Laramie to Hot Spring Gate, although still passing over prairie country, the average grade of ascent is given by the same explorer as 45 feet per mile. Over this entire route, however, loaded wagons have been transported with ease. When we reach the foot of the mountains in this direction, the lofty elevated ridges seem to rise abruptly out of the prairie, averaging from 1,000 to 6,000 feet in height above the surrounding country. From thence to the Pacific coast we pass over a continued series of elevations which taken in the aggregate seem to trend nearly northwest and southeast, but which, when examined in detail, often present no definite direction or continuous line of fracture. This mountain region is composed of a series of these ridges forming a belt or zone 400 to 800 miles in width from east to west, interspersed with beautiful valleys through which wind streams of clear water. So numerous are the profiles which have now been made across the continent by different explorers that it is hardly necessary to describe each one, since what we have already said indicates the object in view.
We have said that the western portion of our continent, especially if we look only at the easterly slope, may very properly be divided into mountain and prairie. It is true that in Kansas and Iowa, groves of timber of considerable size are seen, but they form rather the exception than the rule. Along the eastern slope there is a belt of country 300 to 600 miles in width, where, for the most part, the only timber to be seen is a thin fringe bordering the streams. Even in the eastern portion of the main range the timber is not luxuriant, like that so common along the coast of Oregon and California. The pine trees are seldom more than 3 feet in diameter.
Again, we may divide the mountains or elevated ridges which form the different ranges into two kinds, viz, those with long extended lines of fracture, with a granitic nucleus and a comparatively regular outline, and those which appear to be composed of a series of cones or peaks more or less intimately connected, exceedingly irregular in their outline and of eruptive origin. Of the first class, the Black Hills, Bighorn, Laramie, and Wind River Mountains are good examples, while the Wahsatch, Green River, Teton Ranges, and many others west of the dividing crest might be cited as illustrations of the second class. From all the information within our reach we have inferred that after passing the eastern slope the mountain ranges of eruptive origin are far the most numerous. We also know from personal observation that the main range of the Rocky Mountains and the subordinate ridges on either side, near the headwaters of the two principal branches, the Yellowstone and Missouri, are of similar origin and present similar rugged features. We may now return to the Cretaceous period. In a previous paper in this journal..
* Vol. xxxi, March, 1861.