76 H. D. Miser— Llano ria, the Paleozoic Land 



carbon ratios of Pennsylvanian coals in northern Texas^^ 



says : > 



' ' The high carbon ratio east of the Carboniferous area, appar- 

 ently higher than that around the Wichita Mountains on the 

 north or the Central Texas Uplift on the south, is very suggestive 

 and apparently points to an area of high disturbance beneath the 

 Cretaceous immediately east of the margin of the latter. 

 Whether there is an old land mass of pre-Pennsylvanian rocks, 

 ah arch of older Pennsylvanian (Bend, etc.) or a series of troughs 

 of the latter between arches of older rocks, is not yet estab- 

 lished." 



Similar conclusions have also been expressed by Fuller 

 in the references cited below.^^ 



Thickness and extent of sediments derived from Llanoria. 



Llanoria was greatly eroded and was of vast size, as 

 shown by the large areal extent and enormous aggregate 

 thickness of the Paleozoic rocks in the Arkansas Valley 

 and Ouachita Mountains and of the Pennsylvanian rocks 

 of north-central Texas. 



The maximum thicknesses of the rock formations in the 

 Ouachita Mountains and Arkansas Valley as given on 

 page 64 aggregate 37,000 feet, but as their thicknesses 

 differ considerably from place to place the total thickness 

 in any particular part of these regions would be less than 

 the aggregate given. Nevertheless the following esti- 

 mates by several geologists of the aggregate thicknesses 

 in different parts of the regions indicate that between 

 20,000 and 25,000 feet of rocks, of which fully 90 per cent 

 are clastic, were laid down in the greater part of the 

 Ouachita geosyncline comprising the present Ouachita 

 Mountains and Arkansas Valley. 



The 'total of the minimum and maximum thicknesses 

 of the rocks in the Atoka and Coalgate quadrangles of 

 Oklahoma, as given by J. A. Taff,^^ are 21,400 and 22,400 



=*^ Fuller, M. L., Eelation of oil to carbon ratios of Pennsylvanian coals in 

 north Texas, Econ. GeoL, vol. 14, no. 7, p. 541, Nov. 1919. 



•'" Fuller, M. L., Carbon ratios in Carboniferous coals of Oklahoma, and 

 their relation to petroleum, Econ. GeoL, vol. 15, No. 3, p. 234, April-May, 

 1920. Discussion of paper by F. B. Plummer on the stratigraphy of the 

 Pennsylvanian formations of North-Centi-al Texas, Assoc. Amer. Petroleum 

 Geologists, Bull., vol. 3, pp. 149-150, 1919. 



^^'Taff, J. A., U. S. GeoL Survey GeoL Atlas, Coalgate folio (No. 74), 

 1901, and Atoka folio (No. 79), 1902. 



