PHYSICAL FEATURES.
A zone of mountains and high plateaus extends from the northern nearly to the southern boundary of Utah Territory. The Wasatch Mountains constitute the northern portion of this zone, the High Plateaus the southern. This central zone has a general altitude above the sea of from nine to eleven thousand feet. Many peaks are higher, a few reaching an altitude of about twelve thousand feet. On the other hand many cañons and valleys have been excavated by the running waters far below the general level thus indicated.
The Uinta Mountains stretch eastward from the midst of the Wasatch. This region is a lofty table land carrying many elevated peaks whose summits are from twelve to nearly fourteen thousand feet above the level of the sea. This is the highest portion of Utah, and among its peaks are the culminating points.
South from the Uinta Region, and from the southern extremity of the Wasatch Mountains, another elevated district extends east-southeast beyond the borders of Utah. This table land is cut in twain by two great gorges of the Green River—the Cañon of Desolation and Gray Cañon. The eastern portion is called East Tavaputs Plateau, the western West Tavaputs Plateau.
Between the Uinta Mountains and the Tavaputs table land is the Uinta-White Basin, a low synclinal valley, drained by the Uinta and its ramifications on the west, and the lower portion of the White River on the east.
The district of country lying south of the Tavaputs table land, and east and south of the High Plateaus, is traversed by many deep cañons. This is the Cañon Land of Utah. In its midst the Green and Grand unite to form the Colorado. The Price and San Rafael are tributary to the Green. The Fremont, Escalante, Paria, Kanab, and Virgin are directly tributary to the Colorado from the north and west. From the east the San Juan flows to the Colorado, but its drainage area is not included in our present discussion.
West of the lofty zone lie low, arid valleys, interrupted by short and abrupt ranges of mountains whose naked cliffs and desolate peaks overlook the still more desolate valleys. These short longitudinal ranges are but a part of the Basin Ranges, a mountain system extending through Nevada and northward into Idaho and Oregon. That portion of the Basin Range System which lies in Utah, and which we now have under consideration, is naturally divided into two parts, the northern embracing the drainage area of Great Salt Lake, the southern embracing the drainage area of Sevier Lake, giving the Great Salt Lake District and the Sevier Lake District.
To recapitulate, the grand districts into which Utah is naturally divided are as follows: The Wasatch Mountains and the High Plateaus, constituting the lofty zone above mentioned; the Uinta Mountains, the Tavaputs table lands, the Uinta-White Basin, the Cañon Lands, the Sevier Lake Basin, and the Great Salt Lake Basin, the two latter being fragments of the great Basin Range Province.
The eastern portion of the Territory of Utah is drained by the Colorado River by the aid of a number of important tributaries. The western portion is drained by streams that, heading in the mountains and high plateaus of the central portion, find their way by many meanderings into the salt lakes and desert sands to the westward.
Considered with reference to its drainage, Utah may thus be divided into two parts—the Colorado drainage area and the Desert drainage area; the former is about two-fifths, the latter three-fifths of the area of the territory.
All of the Wasatch Mountains lie west of the drainage crest; a part of the High Plateaus are drained to the Colorado, a part to the deserts. This great water divide, commencing north of the Pine Valley Mountains in the southwest corner of the territory, runs north of the Colob Plateau and enters the district of the High Plateaus. It first runs eastward along the crest or brink of the Pink Cliffs that bound the Markagunt and Pauns-a-gunt Plateaus, and then north and east in many meandering ways, now throwing a plateau into the western drainage, and now another into the eastern, until it reaches the western extremity of the Tavaputs table lands. Thence it runs around the western end of the Uinta Valley, throwing the Tavaputs table lands, the Uinta Valley, and Uinta Mountains into the Colorado drainage, and the Wasatch Mountains into the Desert drainage.
These two regions are highly differentiated in orographic structure and other geological characteristics. The sedimentary formations of the eastern region are in large part of Cenozoic and Mesozoic age, though Paleozoic rocks appear in some localities. The Cenozoic and Mesozoic formations are largely composed of incoherent sands and shales with intercalated beds of indurated sandstone and limestone. The great geological displacements are chiefly by faults and monoclinal flexures, by which the whole country has been broken up into many broad blocks, so that the strata are horizontal or but slightly inclined, except along the zones of displacement by which the several blocks are bounded. Here the strata, when not faulted, are abruptly flexed, and the rocks dip at high angles.
The Uinta Mountains are storm carved from an immense uplifted block. The mountains of the Cañon Lands are isolated and volcanic. In the High Plateaus sedimentary beds are covered by vast sheets of lava. The sedimentary beds exposed in the mountains of the Desert region are of Paleozoic age, and many crystalline schists appear, while the sedimentary beds exposed in the valleys are Post-Tertiary. The crystalline schists and ancient sedimentaries of the mountains are often extensive masses of extravasated rocks. The prevailing type of orographic structure is that of monoclinal ridges of displacement. Blocks of strata have been turned up so as to incline at various angles, and from their upturned edges the mountains have been carved. But these monoclinal ridges are much complicated by mountain masses having an eruptive origin.
In the eastern districts the materials denuded from the mountains and plateaus have been carried to the sea, but in the western districts the materials carried from the mountains are deposited in the adjacent valleys, so that while the mountains are composed of rocks of great age, the rocks of the valleys are of recent origin. In that geological era known as the Glacial epoch the waters of a great lake spread over these valleys, and the mountains stood as islands in the midst of a fresh-water sea. For the history of this lake we are indebted to the researches of Mr. Gilbert. It had its outlet to the north by way of the Shoshoni River and the Columbia to the North Pacific. These later beds of the valleys are in part the sediments of Lake Bonneville, the great lake above mentioned, and in part they are subaërial gravels and sands.
The Wasatch system of mountains is composed of abrupt ranges crowned with sharp peaks. The several minor ranges and groups of peaks into which it is broken are separated only in part by structural differences, since ridges with homogeneous structure are severed by transverse valleys. The drainage of the whole area occupied by the Wasatch Mountains is westward to the Great Salt Lake. The streams that head in the western end of the Uinta Mountains and West Tavaputs Plateau cut through the Wasatch Mountains.
Great Salt Lake and its upper tributary, Utah Lake, exist by virtue of the presence of the Wasatch Mountains, for the mountains wring from the clouds the waters with which the lakes are supplied.
Walled by high ridges and peaks, many elevated valleys are found. In the midsummer months these valleys are favored with a pleasant, invigorating climate. Occasionally showers of rain fall. Vegetation is vigorous. The distant mountain slopes bear forests of spruce, pine, and fir; the broken foot hills are often covered by low, ragged piñon pines and cedars; and the flood plains of the streams are natural meadows. About the springs and streamlets groves of aspen stand, and the streams are bordered with willows, box elders, and cottonwoods. Now and then a midsummer storm comes, bringing hail, and even snow. When the short summer ends, the aspen and box elder foliage turns to gold flecked with scarlet; the willows to crimson and russet; the meadows are quickly sered, and soon the autumn verdure presents only the somber tints of the evergreens; early snows fall, and the whole land is soon covered with a white mantle, except that here and there bleak hills and rugged peaks are swept bare by the winds. The brief, beautiful summer is followed by a long, dreary winter, and during this winter of snowfall are accumulated the waters that are to be used in fertilizing the valleys away below in the border region between the mountains and the desert basins.
From the Wasatch on the north to the Colob on the south are elevated tables, in general bounded by bold, precipitous escarpments. The lands above are highly and sharply differentiated from the lands below in climate, vegetation, soil, and other physical characters. These high plateaus are covered with sheets and beds of lava, and over the lava sheets are scattered many volcanic cinder cones. The higher plateaus bear heavy forests of evergreens, and scattered through the forests are many little valleys or meadow glades. The gnarled, somber forests are often beset with fallen timber and a vigorous second growth, forming together a dead and living tangle difficult to penetrate. But often the forest aisles are open from glade to glade, or from border cliff to border cliff. In the midst of the glades are many beautiful lakelets, and from the cliffs that bound the plateaus on every hand the waters break out in innumerable springs.
Here, also, a brief summer is followed by a long winter, and through its dreary days the snow is gathered which fills the lakelets above and feeds the springs along the bordering cliffs. The springs of the cliffs are the fountains of the rivers that are to fertilize the valleys lying to the east, south, and west.
The Uinta Mountains constitute an east and west range. From a single great uplift, nearly 200 miles long and from 40 to 50 miles wide, valleys and cañons have been carved by rains and rivers, and table lands and peaks have been left embossed on the surface. Along its middle belt from east to west the peaks are scattered in great confusion, but in general the highest peaks are near the center of the range. The general elevation descends abruptly both on the north and south margins of the uplift, and at the crest of each abrupt descent there are many limestone ridges and crags. Between these ridges and crags that stand along the bordering crests, and the peaks that stand along the meandering watershed, there are broad tables, some times covered with forests, sometimes only with grass.
This is a third region of short summers and long winters, where the waters are collected to fertilize the valleys to the north and south.
Away to the southward are the twin plateaus, East and West Tavaputs, severed by the Green River. These plateaus culminate at the Brown Cliffs, where bold escarpments are presented southward.
Outlying the Brown Cliffs are the Book Cliffs. These, also, are escarpments of naked rock, with many salient and reëntrant angles and outlying buttes. The beds of which they are composed are shales and sandstones of many shades of blue, gray, and buff. In the distance, and softly blended by atmospheric haze, the towering walls have an azure hue. Everywhere they are elaborately water carved, and the bold battlements above are buttressed with sculptured hills. In 1869, when the writer first saw this great escarpment, he gave it the name of the Azure Cliffs, but an earlier traveler, passing by another route across the country, had seen them in the distance, and, seizing another characteristic feature, had called them the Book Mountains. Gunnison saw, however, not a range of mountains, but the escarped edge of a plateau, and this escarpment we now call the Book Cliffs. From the Brown Cliffs northward these plateaus dip gently north to the Uinta-White Basin. From the very crest of the Brown Cliffs the drainage is northward.
This is a fourth region of short summers and long winters, where the moisture is collected to fertilize adjacent lands; but the altitude is not great enough nor the area large enough to accumulate a large supply of water, and the amount furnished by the Tavaputs Plateaus is comparatively small.
Such are the lofty regions of Utah that furnish water to irrigate the lowlands.