While Pennsylvanian and Permian sediments were being deposited in and southwest of the park, a large area to the northeast—called by geologists the Uncompahgre highland, because it occupied the same general area as the present Uncompahgre Plateau—rose slowly above sea level. Whatever Paleozoic rocks there were on this rising land, plus part of the underlying Precambrian rocks, were eroded and carried by streams into deep basins to the northeast and southwest. Thus, while mostly marine or nearshore deposits were being laid down in and near the park, thousands of feet of red beds were being laid down by streams in an area between the park and the Uncompahgre Plateau. During part of Middle Pennsylvanian time a large area including the park and known as the Paradox Basin was alternately connected to or cut off from the sea, so the water evaporated during cutoff periods and was replenished during periods when connection with the sea resumed. In this huge evaporation basin were deposited the layers of salt and gypsum plus some potash salts and shale that now make up the Paradox Member. The old Uncompahgre highland continued to shed debris into the bordering basins until Triassic time, when it began to acquire a veneer of red sandstone and siltstone of the Chinle Formation (Lohman, 1965). The area remained above sea level during the Triassic Period and most if not all the Jurassic Period, although the Jurassic Carmel Formation was laid down in a sea that lay just to the west. Late in the Cretaceous Period a large part of central and southeastern United States, including the eastern half of Utah, sank beneath the sea, as shown in figure 81, and received thousands of feet of mud, silt, and some sand that later compacted into the Mancos Shale. This formation and all the younger and some older strata have long since been eroded from the park area but are present in adjacent areas, such as the lower slopes of the Book Cliffs north of Green River, Crescent Junction, and Cisco (fig. 7). The land rose above the sea at about the close of the Cretaceous and has remained above ever since, although inland basins and lakes received sediment during parts of the Tertiary Period. Compressive forces in the earth’s crust produced some gentle folding of the strata at the close of the Cretaceous, but more pronounced folding and some faulting occurred during the Eocene Epoch, when most of the Rocky Mountains took form. During the Miocene Epoch molten igneous rock welled up into the strata to form the cores of the nearby La Sal, Abajo, and Henry Mountains (fig. 7). Additional uplift and some folding occurred in the Pliocene and Pleistocene Epochs. [Illustration: LATE CRETACEOUS SEA, which covered parts of central and southeastern United States. (Fig. 81)]