Area in Louisiana and Eastern Texas. 75 



now covered by later formations, and only a very small 

 part of it from the older rocks of the Central Mineral 

 region. His reasons for this conclusion may be briefly 

 summarized as follows : 



1. The outcrop or strike of the beds is almost at right 

 angles to the northern border of the Central Mineral 

 region. 



2. The beds indicate deeper v/ater and slower deposi- 

 tion near the Central Mineral region than farther north. 



3. Each bed at or near the border of the Central Min- 

 eral region dips westward and overlaps in this direction 

 the underlying beds, in much the same way that the 

 younger foreset beds of delta deposits overlap the older 

 beds. 



4. Conglomerates extend almost to Eed River, and 

 the pebbles composing them remain remarkably uniform 

 in character; they include no pebbles of limestone and 

 marble such as would be derived from the rocks in the 

 Central Mineral region. 



5. The beds indicate that the sea was deeper to the 

 west than to the east. 



The same view regarding the source of the land-derived 

 sediments of the Pennsylvanian rocks of north-central 

 Texas has been expressed by C. L. Baker,^^ R. T. Hill,-'^ 

 E. T. Dumble,^^ and F. B. Plummer,^^ but Hill at the same 

 time expressed the view that an old land mass in eastern 

 Texas also supplied the sediments for the Carboniferous 

 rocks in southeastern Oklahoma and western Arkansas. 



Carlson ratios of Pennsylvanian coals in northern Texas. 

 M. L. Fuller in a recent paper on the relation of oil to 



^' Udden, J. A., Baker, C. L., Bose, Emil, Eeview of the geology of Texas, 

 Texas Univ., Bull. No. 44, pp. 106-107, 1916. 



^^Hill, E. T., Geography and geology of the Black and Grand prairies, 

 Texas: U. S. Geol. Survey, Twenty-first Ann. Eept., pt. 7, pp. 91-92, 103-104, 

 1901. 



^'Dumble, E. T., The individuality of Texas geology, The Eice Institute 

 pamphlet, vol. 3, No. 2, pp. 155-156, April, 1916. Origin of the Texas 

 domes, Am. Inst. Min. Eng., Bull. 142, p. 1634, Oct., 1918. The Geology of 

 East Texas, Univ. of Texas Bull. No. 1869, pp. 11-13, 1920. Discussion of 

 paper by E. DeGolyer on the theory of the volcanic origin of salt domes. 

 Am. Inst. Min. and Met. Eng., Trans., vol. 61, p. 476, 1920. 



■"' Plummer, F. B., Preliminary paper on the stratigraphy of the Pennsyl- 

 vanian formations of north-central Texas (unpublished manuscript). 



