YELLOWSTONE NATIONAL PARK SHEETS. GENERAL DESCRIPTION. features of central Wyoming, and is one of the the amount of precipitation is higher, and the tion of the schists and granites under atmospheric longest and broadest ranges in the State, extend­ mean annual temperature lower. Rain storms agencies. These earlier sediments everywhere BY ARNOLD HAGUE, ing in a series of high alpine ridges well up occur frequently throughout the summer, while consist of coarse quartz grains and fragmentary S---71I GEOLOGIST IN CHARGE. toward the Park. An outlying ridge within the snow is likely to fall at any time between Sep­ material of the underlying rocks. Over this area of the map has been designated Big Game tember and May. Such climatic conditions favor comes somewhat finer and lighter material, carry­ GEOGRAPHY. Ridge, and the culminating point has long been forest development and the growth of luxuriant ing mica and clay, the latter derived from the The area covered by the maps of the Yellow- known as Mount Hancock. This mountain, grasses, together with a varied alpine verdure. decomposition of the feldspars contained in the stone National Park folio is represented upon situated just inside the southern line of the These conditions, with numerous mountain tor­ crystalline rocks. Overlying these latter beds four atlas sheets, known as the Gallatin, Canyon, Park, has an altitude of 10,100 feet above sea- rents, plateaus, lakes, and waterfalls descending the first calcareous sediments were deposited, Lake, and Shoshone sheets, and is embraced level, and commands one of the most picturesque from the table-land to the lowland, add much to associated with quartz and mica and carrying less between the parallels of 44° and 45° north lati­ views of the adjacent country. the scenic attractions of the far-famed Yellow- and less foreign material, until beds of nearly tude and the meridians of 110° and 111°. It is Along the entire eastern side of the Park stone Park. Owing to the elevation of the coun­ pure limestone made their appearance. In these situated in the northwest corner of the State of stretches the Absaroka Range, so called from the try and consequent severity of its climate, the beds occur the first remains of a marine fauna, Wyoming, and includes 3,412 square miles. Indian name of the Crow Nation. At its south­ region is one unfit for agriculture and undesir­ showing a grouping of species characteristic of In 1871 Dr. F. V. Hayden, a United States ern end the range is topographically so closely able for settlement, and as the Park and Forest the middle Cambrian period. From the base of geologist, explored this region, at that time com­ connected with the Wind River Range by the Reservation are under Government supervision, this limestone to the top of the Madison forma­ paratively unknown, accompanied by a corps of Wind River Plateau that any line of separation no person is allowed to reside there permanently tion the great limestone body of the Carbon­ skilled scientific assistants including geologists between them must be drawn arbitrarily. The or without permit from the Secretary of the iferous period in the northern Rocky Mountains and topographical engineers. Their explorations Absarokas trend in a north-south direction for Interior. Good roads traverse the country and the beds consist almost wholly of calcareous were eminently successful, and immediately more than 80 miles, forming an unbroken barrier substantial bridges span the rivers, both being deposits, varying considerably, however, in the attracted the attention of the world. It must along the entire eastern side of the Park. All the built and maintained by the General Govern­ purity of their sedimentation, some of them always redound to the credit of Dr. Hayden that western slope of the mountains and many of the ment. arenaceous, others more or less argillaceous, while he appreciated the exceptional character of the higher peaks come within the Park limits, but GENERAL GEOLOGY. still others are marked by the presence of ferru­ region and the advisability of its forever being the great body of the range lies to the eastward, Archean rocks. The oldest rocks in this region ginous material and belts of cherty and nodular held intact by the General Government. He presenting an uncommonly rugged group of are crystalline granites, gneisses, and schists of limestones. Differences of color, mode of bed­ laid the matter before the Congress of the United peaks and mountain masses, scored by deep various kinds, and, like similar occurrences else­ ding, and a tendency of certain beds to assume a States, and upon his earnest solicitation the Yel- canyons. Near the northeastern corner of the where, are assigned to the Archean age. They shaly structure, render it possible to separate this lowstone National Park was established. Park a confused mass of mountains connects the are thought to constitute the earlier rock forma­ great body of limestone into a series of beds. By far the greater part of the Yellowstone Absarokas with the Snowy Range. The latter tions of the crust of the earth. The granites and Many of them are easily recognized and their Park is situated within the area of the four atlas range, high and alpine in character, as its name gneisses are for the most part coarsely crystalline, geological position determined wherever they are sheets, but a strip of country about 2|- miles in indicates, shuts in the Park on the north, its west­ and the entire series shows the eiiect of meta- exposed. One of these characteristic beds in the width lies to the northward in Montana, and a ern foothills connecting with the outlying eastern morphism by pressure. No exposures of Archean Cambrian has been designated the Mottled lime­ still narrower belt extends along the western side spurs of the Gallatin Range. Only the southern rocks are known in the central region, but they stone, so named from the irregular dark-gray and in Idaho and Montana. The eastern boundary of end of the Snowy Range falls within the borders occur in connection with all the great mountain brown lenticular patches scattered through it. It the Park, as defined by law, is placed 10 miles of the Park reservation. uplifts that encircle the Park plateau. In con­ is a persistent horizon, easily traced far beyond east of the most eastern point of the Yellowstone Across the elevated plateau inclosed by these sequence, they are found only near, the borders of the limits of the Park region. No well-preserved Lake. This eastern line nearly coincides with mountains lies the continental divide, separating the district, where, with the exception of those organic remains have been found in it, but the the meridian of 110°. The southern boundary the waters of the Atlantic from those of the found in the Gallatin Range, they represent out­ fauna found below it has been referred by Mr. lies 10 miles south of the lake, and is shown on Pacific. Entering the Park at the southeast cor­ lying portions of much larger masses. In the C. D. Walcott to the middle Cambrian, while all the maps (Shoshone and Lake sheets). ner, it runs with an irregular course in a north­ Snowy Range they occur along the northern fossils immediately above this horizon in the In the organic act of 1872, defining the pur­ west direction. Following along the top of Two border of the map, and are found on both sides Gallatin Range belong to the upper Cambrian. poses and boundaries of the Park, Congress Ocean Plateau, it skirts the northern escarpment of the Yellowstone for a long distance. Along The Cambrian has an estimated thickness of 860 declared that the reservation was " dedicated and of Flat Mountain, winds among the undulating Big Game Ridge and in the mountain mass of feet. set apart as a public park and pleasure ground low ridges lying between Yellowstone and which Wildcat Peak is one of the culminating The beds assigned to the Silurian, consist of for the benefit and enjoyment of the people." As Shoshone lakes, and thence, with a broad sweep­ points, no Archean rocks occur, but southward, dark-colored, massive limestones, for the most defined by law, the area of the Yellowstone ing curve around the streams running into the in the Wind River Range, as in the Tetons, they part sharply defined lithologically, but in the National Park includes 3,344 square miles. latter lake, crosses the Madison Plateau and form the central body of the mountains. Gallatin Range poorly defined by organic remains. All the country situated between the southern leaves the Park a short distance southwest of the Algorikicm rocks. In the Rocky Mountains As the Cambrian limestone passes into that of line of the Park and the parallel of 44° belongs Upper Geyser Basin. north of the Yellowstone Park there rests uncon- the Silurian without any marked change of to what is known as the Yellowstone Park Forest Four large rivers drain this region. The Snake formably upon the Archean a series of sandstones deposition, it is natural that conditions favorable Reservation, set aside by proclamation of Presi­ carries off all the water on the south and west and slates which have been referred to the to the development of many preexisting species dent Harrison on March 30, 1891, and therefore side of the great divide, and the Yellowstone, Algonkian period, yielding as yet no organic should continue upward into higher horizons, and may be regarded as practically forming a part of Madison, and Gallatin that on the east and north. remains. Within the Park, rocks provisionally that there should be a commingling of both the the grand National reservation.