68 H. B. Miser — Llanoria, the Paleozoic Land 



E. 0. Ulrich,^^ who has made field studies of the forma- 

 tions under discussion, holds: (1) that the Hot Springs 

 sandstone and Stanley shale are equivalent to the Chester 

 group and to beds that bridge the Chester-Pottsville 

 interval, (2) that the Jackfork sandstone is of lower 

 Pottsville age, and (3) that the Caney shale is of upper 

 Pottsville age. The reasons for these opinions can not 

 be discussed here for lack of space. 



Evidence for a Paleozoic land arEx^ in Louisiana and eastern 

 Texas, and its features. 



Any land area that may have existed in Louisiana and 

 eastern Texas during the Paleozoic era is now largely if 

 not entirely concealed by Cretaceous and younger sedi- 

 ments of the Gulf Coastal Plain. Evidence regarding it 

 must therefore be obtained from (1) the Paleozoic and 

 older rocks that are exposed in the regions bordering the 

 Gulf Plain, (2) the structure of the sediments of the Gulf 

 Plain, and (3) wells that have passed through the Creta- 

 ceous and younger rocks of the Gulf Plain and penetrated 

 the underlying Paleozoic and pre-Cambrian rocks. This 

 evidence follows. 



General character of Ordovician and Silurian rocks in Ouachita 



Mountains. 



The rocks of Ordovician and Silurian age exposed in 

 the Ouachita ^lountains consist mainly of shale and 

 sandstone, whereas the rocks of these ages in the Arbuckle 

 Mountains, in the Ozark region, and in the Nashville dome 

 in middle Tennessee consist predominantly of limestones. 

 This strongly suggests that the present Ouachita region 

 was near an old land area undergoing vigorous erosion 

 during these two periods, and if this is true it is necessary 

 to assume that the old land area existed south of the 

 present Ouachita Mountains. 



Blakely sandstone of Ouachita Mountains. 



The Blakely sandstone, of Ordovician age, thins out 

 to the north in Montgomery County, Ark. This forma- 

 tion is 500 feet or less thick and is composed largely of 

 shale but partly of sandstone, though the sandstone is 



^^ Oral communication. 



