The salt anticlines of eastern Utah and western Colorado formed in the deepest part of Paradox basin, a basin developed during Pennsylvanian time and filled by great thicknesses of upper Paleozoic sediments, including a thick sequence of evaporites belonging to the Paradox member of the Hermosa formation. The salt anticlines originated either as tectonic folds or as folds over basement faults soon after the evaporites were deposited, probably in Middle Pennsylvanian time. These structures were parallel to and probably formed concomitantly with the rise of the ancestral Uncompahgre highland, the front of which paralleled rather closely that of the southwest front of the present-day Uncompahgre Plateau. Rapidly accumulating arkosic sediments of the Permian Cutler formation, derived from this highland, probably buried parts of the salt anticlines; elsewhere along the anticlines the salt rose isostatically as rapidly as the sediments were deposited. In places the Cutler was later intruded by the cores of the buried salt anticlines. Parts of the cores were exposed at the surface at least until the Morrison formation was deposited in Late Jurassic, so that the formations pinch out along the flanks of the salt cores. Variations in thicknesses--chiefly thinning--of the Morrison and later Mesozoic formations over the crests of the salt cores indicate that salt flowage was still active after the salt cores were buried.

The salt anticlines attained their present form--except for modifications imposed by later collapse of the crestal parts of the anticlines--during the early Tertiary when the rocks of the region were folded, and the salt anticlines were accentuated.

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