The fresh-water Tertiary of northwestern Texas : American Museum expeditions of 1899-1901. Bulletin of the AMNH ; v. 19, article 26.

Abstract

"Following is a summary of the conclusions reached by the writer from this study of the formations of northwestern Texas: (1) There has been no great disturbance or change of level in the region of the Staked Plains since the close of the Triassic, hence the strata of the Triassic which underlie this whole region are for the most part nearly horizontal, and the country at the beginning of the Miocene was comparatively level. (2) The Panhandle (Lower or Middle Miocene) beds were comparatively evenly distributed over the vast area now occupied by the Staked Plains and in addition extended westward to the Rocky Mountains in New Mexico, and spread out to the eastward over a much greater territiory than they now occupy. These deposits seem to be, at least partially, lacustrine in origin. (3) All the formations of the Staked Plains that are of more recent date than the Lower or Middle Miocene are represented by comparatively small areas, and are fluviatile, or aeolian and fluvaiatile, in origin. These later depositions are represented by the Clarendon beds in the vicinity of Clarendon, the Blanco Beds at Mount Blanco, and the Rock Creek beds at Tule Cañon and Rock Creek"--P. 635.