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their present, outcrop, which occupied the present site of the East-Central and Eastern provinces, as is more fully set forth in the section on the geologic structure.

The Carboniferous portion of these rocks at least has been considered to represent the southwestern continuation of the Missouri and Arkansas strata of the Mississippian field, for the rocks disappear westward beneath later formations of the Central and Plateau provinces. Their buried westward continuation supposedly occupies a great synclinal trough beneath the provinces last mentioned, the western limb of which reappears in the upturned flanks of the Cordilleras.

The Carboniferous and Permian formations occur in a series of parallel belts of outcrop one succeeding another to the northwest in ascending series. The belts extend from southern Kansas and eastern Indian Territory toward south-central Texas, occupying the Central Province of the Greater Plains region. The plications of the eastern or Massern Ranges of the Ouachita system are the most eastern belt, while the Arbuckle and Wichita ranges are plications directly across the strike of the more westerly belts, which are separated by them into northern and southern areas.

Although the general features of some of these belts of outcrop may be traced from Kansas River in Kansas to the Colorado in Texas, a distance of over 500 miles, except where they cross the Ouachita trends, no attempt has been made to outline them as a whole, and the classification herein used must be considered temporary and provisional. In general, their occurrence by districts may be stated as follows:

-The most eastern belt may be termed the Ouachita. This comprises the outcrop of the lower rocks of the Carboniferous, principally sandstones and shales, which compose the Massern Ranges of Arkansas and Indian Territory. Similar rocks outcrop at intervals in the Palo Pinto, Brownwood, and Smithwick districts of Texas, along the interior margin of the Grand Prairie.

-Succeeding the Ouachita belt to the northwest there is usually a region of prairie underlain largely by arenaceous shales of the Coal Measures. This constitutes the prairies of eastern Kansas and north-central Indian Territory. In Texas the rocks of this district are represented along a belt through Cisco and west of Brownwood.

-This is a narrow strip of prairie country, underlain by yellowish limestones and shales of the Permo-Carboniferous, which extends from Kansas River at Fort Riley southward via Arkansas City "

This fact is developed by J. C. Branner in Am. Jour. Sci., 4th series, Vol. IV, 1897, pp. 357-371.

Carboniferous rocks also occur in the Guadalupe and other ranges of the Trans-Pecos Mountains. These belong to a distinct province from that of the phenomena discussed in the present paper, being separated from the latter by the Great Plains and the Central Province.