99

measurement on a line run from the upper part of the measures at the northeast corner of Throckmorton County to the west line of Hood County." The section as thus stated is given from above downward and against the dip, which is to the west. The lower beds of the section are at the west line of Hood County and the upper beds at the northeast corner of Throckmorton County.

This section by Cummins does not represent the entire thickness of the Carboniferous series, for these continue downward from 1,500 to 3,000 feet lower than the base of Cummins's section, beneath the overlap of the Cretaceous formation of the Grand Prairie region to the eastward. The deep artesian well at Fort Worth, 40 miles from the nearest Carboniferous outcrop, after passing through 1,200 to 1,400 feet of Cretaceous, penetrated nearly 1,500 feet of Carboniferous strata.

In the Ouachita and Muscogee districts the relations of the beds which initiate the Carboniferous proper to the Marble Falls and Bend limestones of the base of the Texas sections can not be stated at present. The basal Carboniferous of the Ouachita and Muscogee districts is succeeded by shales and sandstones, which in a general way are the equivalent of the Richland formation of Texas. In the Ouachita district the beds are intensely folded. The chief characteristic of the Indian Territory section of the districts mentioned is its tremendous thickness in comparison with that of Texas, which leads to the belief that a previous and at present inexplicable pre-Carboniferous topographic barrier in some manner separated or partially separated the deposition areas of Texas from those of northern Indian Territory in Carboniferous time.

The Eocarboniferous, which may be absent in Texas, is well represented at the base of the series in Indian Territory, although, so far as the writer is aware, it has not been detected in the Ouachita district. No strong line of demarcation is found between the Eocarboniferous and the Carboniferous. According to Drake the latter in its entirety consists of shales, grits, and sandstones, attaining the enormous thickness of 24,500 feet.

The Muskogee section is divided by Drake into the Lower and Upper Coal Measures, but to all intents and purposes it is practically a continuous formation. These beds homotaxially are equivalent to the Richland, Brownwood, and Waldrip divisions of the Texas section.

Throughout their extent in Kansas, Indian Territory, and Texas the western outcrops of the Coal Measures proper grade up without "

Proc. Am. Philos. Soc., Vol. XXXVI, 1898, p. 361.