n6 C H. GORDON 



iferous. Owing to the hardness of the rock, however, good speci- 

 mens are difficult to obtain. Toward the south there is an increase 

 in the development of blue shale and limestone, while the red clays 

 and sand show a corresponding diminution. In a recent paper 1 

 Case has endeavored to correlate certain of the sandstones occur- 

 ring throughout the area, one of which he calls Fulda, from a little 

 station by that name in eastern Baylor County. With this sand- 

 stone he correlates others which outcrop as far east as Wichita 

 Falls, a distance of 37 miles. With this conclusion the writer is 

 not in accord. In the first place, the sandstones at Fulda are 

 underlain by some thin limestones which outcrop toward the north- 

 east in the northwestern part of Archer County. It is quite 

 apparent that the sandstones in eastern Archer and Wichita 

 counties represent horizons below these limestone beds. Assum- 

 ing the general westward dip of the strata to be no more than 20 

 to 25 feet per mile, there must be a descent of not less than 650 

 to 800 feet to which must be added the rise of the plateau surface 

 which is about 200 feet, making a total of 850 to 1,000 feet between 

 the horizon represented at Wichita Falls and that at Fulda and 

 rendering untenable the correlations suggested. 



Albany area. — The eastern boundary of the Clear Fork and 

 Double Mountain formation in eastern Jones County is marked 

 approximately by the Clear Fork River. The region to the east 

 of this point to the limits of the Cretaceous in western Parker and 

 Wise counties, a distance of over 100 miles, known as the Brazos 

 Coal Field, is occupied by rocks of Carboniferous age. These beds, 

 which have a thickness of nearly 7,000 feet, present lithological, 

 stratigraphic, and faunal characteristics, which permit their 

 separation into four well-marked divisions, known as the Strawn, 

 Canyon, Cisco, and ' 'Albany" divisions. 2 Southward in the Colorado 

 Coal Field the equivalent rocks were first studied by Tarr, 3 who 



1 E. C. Case, Bulletin of the American Museum of Natural History, XXIII (1907), 

 659-664. 



2 These names appear first in the First Annual Report of the Geological Survey oj 

 Texas in the State Geologist's "Report of Progress," pp. lxv-lxvii. Hill, however, 

 credits them to Cummins (Twenty-first Annual Report, U.S. Geological Survey, Part 

 VII, 97). 



3 R. S. Tarr, First Annual Report of the Geological Survey of Texas (1889), 201-16. 



