Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/322

308 Blue, the Great and Little Nemaha, and Salt Creek. The water-power of the State is enormous. Though the streams meander through broad bottoms, places can be found every few miles where the fall is from 3 to 10 feet to the mile.

Flora. Nebraska is the meeting-place of two rather distinct floras that of dry regions from the west, and their relatives from the moister east. Even many native Rocky Mountain plants have crept down to the plains of Nebraska. Of plants indigenous to the State 2000 species have been collected; among these, 1671 species are flowering plants. The Composite?, are represented by the largest number of species, there being 244 within the State. The sedges are represented by 151 species, though there are comparatively few individuals. The grasses are the leading vegetable forms in the number of individuals, though as yet only 147 species have been detected. Originally the short buffalo grass (Buchloe dactyloides) was everywhere abundant, but it has almost entirely disappeared from the eastern half of the State and from large sections in its western portions, the taller blue-joint (Andropogon furcatus, &c.) grasses taking its place. Nothing can surpass the beauty of the prairies during the summer season when covered with rank grasses and myriad flowers. Of forest trees 71 species are native. The leading variety in the number of indi viduals and forests is the cotton-wood (Populus monilifera), which grows luxuriantly on river bottoms and many uplands. The ash-leaved maple, soft maple, elms, various species of ash, lindens, and willows are in various parts of the State about equal in abund ance. The most valuable tree is the noble black walnut, which is extremely hardy and grows luxuriantly. The red cedar is abun dant in some sections, and grows well everywhere. Two species of spruce and two of pine are found on tributaries of the Niobrara and Loup, and in the extreme western part of the State. Shrubs are represented by 91 species. Wild fruits abound, among which plums and grapes are most conspicuous, the former represented by three species and an endless number of varieties. The grapes are limited to timber belts, where they sometimes grow so luxuriantly as to make an almost impenetrable thicket of vines. The smaller wild fruits are widely distributed over the State.

Fauna. Before the advent of the white man Nebraska was a paradise for wild animals, the buffalo, elk, deer, antelope, beaver, wolves, lynx, foxes, &c. The buffalo has been banished, but the rest are still found in the sparsely settled sections of the State. The bird fauna is well developed, being rich in genera (156) ; the species number at least 261. Many species of fish, molluscs, and a few reptiles are present in the streams. During a few years, and notably in 1874, 1876, and 1877, the migrating locust (Caloptenus spretus), whose native habitat is beyond Nebraska, did considerable damage. It does not appear on the average more than once in a decade, and owing to the continually increasing area brought under cultivation the damage from its visitations is continually growing less. Com paratively little damage has yet been experienced from other insect pests.

EB9 Nebraska - geological map.jpg

Geology. No Archaean rocks are found in situ in the State. The Paloeozoic system is represented only by rocks of Carboniferous age, which are found in south-eastern Nebraska, and cover an area of about 2500 square miles. These represent only the Upper Carboniferous, and are mainly yellowish micaceous sandstone, drab, greenish, lead-coloured, ash-coloured, and brownish clays, and indurated, hard, greyish and yellowish limestones. No thick beds of coal have yet been discovered. The lower coal horizon is about 800 feet below the surface along the Missouri as far south as Richardson county, where the upper strata indicate a possible lower level geologically than is exposed elsewhere in the State. Thin beds of coal, from 6 to 18 inches thick, are found near the surface in Cass, Otoe, Nemaha, Johnson, Pawnee, and Richardson counties ; in the last occurs the best coal yet found in the State. At Aspinwall and on the State boundary it is 24 inches thick in places. In the south-western part of the county a bed occurs from 20 to 28 inches thick, from which at least half a million bushels have been taken within two years to supply local demands. This bed has been traced from east to west about 20 miles, and from north to south 4 miles. The coal is of good quality. On the west side of the Carboniferous formation, and commencing at the mouth of Salt Creek, is a narrow strip of Permian rocks which on the Kansas line is about 15 miles broad. The rocks are mainly variously-coloured magnesian limestone, full of geode cavities, the entire thickness ranging from 20 to 100 feet. The Jura Trias is entirely wanting in eastern Nebraska. Resting conformably on the Permian are the various strata of the basal- members of the Cretaceous system. Variegated clays are overlaid by reddish brown conglomerates and sandstones which form the Dakota group, whose thickness ranges from 20 to 300 feet. Above this group occur blackish and ash-coloured shales ; then a yellowish limestone ; then a layer of whitish limestone full of shells called the Inoceramus bed ; and then on top towards north-eastern Nebraska a great thickness of impure chalk rock varying in hue from greyish white to a blueish pink and yellow. These beds constitute the Colorado group, or the Fort Benton and Niobrara groups of Meek and Hayden, and vary in thickness from 100 to 500 feet. Next above occur the shales containing selenite that constitute the Fort Pierre Cretaceous, which are only found in Nebraska in Holt county and on the upper Republican river. At the close of the Fort Pierre epoch Nebraska was again a dry land surface, and remained so through the Fox Hills (Upper Cretaceous) epoch. In extreme south-western Nebraska a small area is covered in isolated spots by the shales and sandstones of the Laramie, or transition group between the Cretaceous and Tertiary. No Eocene beds exist in Nebraska. Miocene beds exist in the north-western part of the State, but during this period the remainder of Nebraska continued to be a land surface which supported a gigantic forest vegetation and an abundant mammalian animal life. The deposits in the Miocene section are mainly indurated grits, silicates of lime, sandstones, conglomerates, and tabular limestones. Towards the close of the Miocene a further subsidence of the region of the plains inaugurated the Pliocene epoch. The great lake now extended as far east as Columbus, covering at least three-fifths of the State and an immense tract outside of its present boundaries. The Pliocene beds are made up of sandstones, conglomerates, marls, and variously-coloured clays. Between the Niobrara and the Loup rivers there are in many places immense quantities of loosely compacted sands, which some geologists, from the abundance of the fossils, have called the Equus beds. On the Republican river curious beds of flour-like geyserite occur. During Pliocene times this was a great geyser region whose activity commenced in the Cretaceous and continued through the Tertiary into the Quaternary. This flour-like material equals for polishing purposes the best tripoli. The thickness of the Pliocene beds in Nebraska ranges from 10 to 700 feet. There is evidence of increasing cold in the upper deposits of the epoch : warm-temperate were gradually dis placed by cold-temperate vegetable forms. The lake itself was drained before the end of the Pliocene.

The memorials of the Glacial epoch are here undoubted. Along the lower Platte, and on the Missouri wherever hard limestone constitutes the surface rocks, they are worn smooth and crossed by glacial scratches in a direction averaging 17 east of south. On the surface rock occur (1) blue clay from 1 to 30 feet thick; (2) modified drift, gravel, and clay from 1 to 9 feet thick ; (3) gravel and boulders 1 to 6 feet thick ; (4) occasionally black soil contain ing large quantities of silicified wood; (5) gravel, sand, and drift boulders ; (6) calcareous sand ; (7) loess from 2 to 200 feet thick ; (8) black surface soil from 1 to 30 feet thick. On the return of mild conditions at the close of &quot;the Great Ice Age&quot; a freshwater lake covered much of Nebraska and the adjoining region on the east and south-east. The sediments brought down by the Missouri in the course of ages filled it up. Thus originated the loess deposits which are the source of the great agricultural wealth of the State. The rising of the land or the removal of barriers effected the drainage of the loess lake. Through the old lake bed the present rivers commenced to cut channels which at first filled the whole of their present valleys. That the loess was a subaqueous deposit is evident from the vast number of freshwater shells entombed in it. It is composed of 81 per cent, of extremely fine siliceous matter, over 3 per cent, of ferric oxide, 10 per cent, of the carbonates and phosphates of lime, and a small amount of carbonates of magnesia, soda, and potash, clay, and organic matter. It forms one of the best soils in the world, and can never be exhausted until the hills and valleys of which it is composed are worn away. The loess and alluvium of the river valleys have a larger amount of organic soil is frequently from 5 to 30 feet thick, than is found on the uplands, where it ranges from 2 to 5 feet. The source of this black soil is the swampy condition that prevailed here towards tke close of the loess age. The rivers often stood long at the same 
 * matter combined with them, especially at the top, where the black