These were followed by a period of minor tilting and faulting in early Mesozoic, by a moderate upwarping in Tertiary, and by a moderate uplift in post-Tertiary time.
Farther south, through Oregon and northern California, many members of the coast ranges resemble the Cascades and the Sierra in offering well-attested examples of the uplift of masses of disordered structure, that had been reduced to a tame surface by the erosion of an earlier cycle, and that are now again more or less dissected.
Since the uplift and stream dissection a slight depression has allowed the sea to invade the lower portions of the river valleys, forming the bays known as Narragansett Bay, Providence "river," Sakonnet " river," &c. Glaciation has disturbed the river 1 Block Island, over which the jurisdiction of the state extends, lies Jo m.
Extensive and deep-seated crumpling was necessarily accompanied by vertical uplift throughout the zone affected, but once at least since their birth the mountains have been worn down to a lowland, and the mountains of to-day are the combined product of subsequent uplift of a different sort, and dissection by erosion.
The mountains rapidly grow wider and higher northward, by taking on new complications of structure and by including large basins between the axes of uplift, tintil in northern Colorado and Utah a complex of ranges has a breadth of 300 m., and in Colorado alone there are 40 summits over 14,000 ft.
The region was by no means a peneplain before its slanting uplift; its surface then was hilly and in the south mountainous; in its central and still more in its northern part it was overspread with lavas which flowed westward along the broad open valleys from many vents in the eastern part: near the northern end of the range, eruptions have continued in the present cycle, forming many cones and young lava flows.
The lower division appears on the Newfoundland and Labrador coasts, and is traceable thence, in a great belt southwest of those points, through Maine and the Hudson-Champlain valley into Alabama, a distance of some 2000 m.; and the rocks are brought up again on the western uplift, in Nevada, Idaho, Utah, western Montana and British Columbia.
Marine deposits were laid down over the south of the state after a submergence of the region; an uplift afterwards made of these deposits a coastal plain.
The ores of the Joplin district, in the Ozark uplift in the Mississippi Valley, are remarkable in that they are specially adapted to mechanical concentration.
North-west of the Bad Lands of the White river lie the Black Hills (q.v.), an irregular dome-shaped uplift, about 125 m.
Are attained in the Boston Mountains, which are the highest portion of the Ozark uplift, and the most picturesque.
An extensive water-parting in the north central part of the state, an elevation whose inclination is almost imperceptible, determines the course of three great continental river systems. From this central elevation the land slopes off in all directions, rising again in the extreme north-east corner, where the rugged granite uplift in Cook county, known as the Misquah Hills, reaches an altitude of 2230 ft., the highest point in the state; and in the south-west corner, where an altitude of 1800 ft.
The rivers are shallow and more or less broken by rapids in the notches; rapids occur also near the outer border of the crystalline belt, as if the rivers there had been lately incited to downward erosion by an uplift of the region, and had not yet had time to regrade their courses.
An uplift, increasing to the south, revealed part of the shallow sea bottom in the widening coastal plain, from its narrow beginning at New York harbour to its greatest breadth of 110 or 120 m.
The coastal plain, however, is the result, not of a single recent uplift, but of movements dating back to Tertiary time and continued with many oscillations to the present; nor is its surface smooth and unbroken, for erosion began upon the inner part of the plain long before the outer border was revealed.
The results of the first cycle of erosion are seen in the widespread exposure of the resistant Carboniferous limestone as a broad platform in the south-western area of greater uplift through central Arizona, where the higher formations were worn away; and in the development of a series of huge, south-facing, retreating escarpments of irregular outline on the edges of the higher formations farther north.
The northernmost part of the coast ranges, in Washington, is often given independent rank as the Olympic Range (Mt Olympus, 8150 ft.); it is a picturesque mountain group, bearing snowfields and glaciers, and suggestive of the dome-like uplift of a previously worn-down mass; but it is now so maturely dissected as to make the suggested origin uncertain.
Then came a broad uplift followed by the erosion which carved out the valleys, leaving hard rocks as mountain ridges which rise about to the level of the old erosion plain.
The uplift is completely enclosed by a rim of hog-back ridges from 300 to Goo ft.
All the higher lands of this area are covered by forests; but the Red Valley, lying between the outer ridges and the main uplift, is treeless.
Although the Coast Prairie is a sea bottom of very modern uplift, it appears already to have suffered a slight movement of depression, for its small rivers all enter embayments; the larger rivers, however, seem to have counteracted the encroachment of the sea on the land by a sufficiently active delta building, with a resulting forward growth of the land into the sea.
As far north as the gorge of the Missouri river in Montana, the Front range, facing the Great Plains, is a rather simple uplift, usually formed by upturning the flanking strata, less often by a fracture.
With the renewal of uplift by which the earlier cycle of erosion was interrupted and the present cycle introduced, inequalities of surface due to renewed faulting were again introduced; these still appear as cliffs, of more nearly rectilinear front than the retreating escarpments formed in the previous cycle.
The few rivers of the region must have reached the quiescence of old age iii the earlier cycle, but were revived by uplift to a vigorous youth in the current cycle; and it is to this newly introduced cycle of physiographic evolution that the deep canyons of the Plateau province are due.
Gold occurs in quartz veins traversing various formations (some as young as Jurassic), and also in gravels, which were for the most part deposited previous to the uplift of the Sierra block.
This epoch of relative uplift and active erosion is sometimes called the Sierran or Ozarkian epoch.
In the third, after the Campagna, by a great general uplift, had become a land surface, volcanic energy found an outlet in comparatively few large craters, which emitted streams of hard lava as well as fragmentary materials, the latter forming sperone (lapis Gabinus) and peperino (lapis Albanus), while upon one of the former, which runs from the Alban Hills to within 2 m.
==Flora== Arkansas lies in the humid, or Austroriparian, area of the Lower Austral life-zone, except the highlands of the Ozark uplift and Ouachita Mountains, which belong to the humid, or Carolinian, area of the Upper Austral.
The sloping surface is gently rolling, and has resulted from the uplift and dissection of a nearly level plain of erosion developed on folded, crystalline rocks.
Arizona itself is mostly included in the great arid mountainous uplift of the Rocky Mountain region, and partly within the desert plain region of the Gulf of California, or Open Basin region.
Its central core of Lower Carboniferous rock is broadly displayed towards the north, while southward it contracts; on either side lie the younger rocks, the coal-fields, the Permian strata and the Triassic formations, the last-named, while sweeping round the southern extremity of the Carboniferous axis of the uplift from its eastern and western flanks, spread out in a large sheet over the midland counties.
The Triassic beds rest on the various Carboniferous series in turn, indicating, as in England, the amount of denudation that followed on the uplift of the Hercynian' land.
Denudation, consequent on the renewed uplift of the country, affected the Jurassic beds until the middle of Cretaceous times.
The Turonian is also sandy, but in most areas was not deposited, or has been denuded away during a local uplift that preceded Senonian times.
Three physiographic regions may be distinguished within the state - the first, a small portion of the Ozark uplift in the extreme south-east corner; the second, the Prairie Plains, covering approkimately the east third of the state; the third, the Great Plains, covering the remaining area.
The elevations of the crest in Missouri (the highest portion of the uplift is in Arkansas) vary from 1100 to 1600 ft.
Until the post-Mesozoic uplift of the Rocky Mountain region the north-western portion of the state drained westward.
Copper occurs in various localities, but is of economic importance only in the Ozark uplift; it was first mined in small quantities in 1837.
EUREKA SPRINGS, a city and health resort, one of the countyseats - Berryville being the other - of Carroll county, in the extreme north-western part of Arkansas, U.S.A., in the Ozark uplift, 1800 ft.
After the uplift which caused the rivers to cut below the general " uplands," and develop well marked valleys for themselves, came the period of the great continental glaciation.
After the uplift came a period of subsidence, during which this region sank one or more thousand feet, allowing the sea to encroach on the land and run far inland into the previously made river valleys.
After the subsidence came another period of uplift, possibly still in progress.