VARIATION IX THE SEDIMENTATION. 315 



where it reaches the foot of the escarpment of the Balcones fault, against 

 which it was deposited, and follows it from thence indefinitely south- 

 westward toward the Rio Grande. The Eocene strikes southward alon^ 

 the line which I have previously indicated upon the maps, but at no 

 place south of Malvern do I know that the denuded outcrop now touches 

 the original shore as far inland as it formerly extended, and one of the 

 great unstudied problems in Texas is the interpretation of this former 

 interior extent of the Eocene beds. 



The beds of the Glauconitic division strike more southward than do 

 those of the Eocene from their last outcrop in northeastern Texas, and 

 are completely overlapped by the latter, except in the Red river coun- 

 ties. Far coastward in the Eocene area — in Anderson, Smith and other 

 counties of Texas, and also in Louisiana, Avhere the Tertiar}^ has been 

 eroded away, these beds are revealed occasionally, as shown by Hilgard, 

 Johnson and Lerch, in small spots, which are sometimes spoken of as 

 " Cretaceous islands," In fact, the Glauconitic beds of Arkansas are all 

 inliers in the Tertiary area.* These outcrops are sufficient to demon- 

 strate that the Glauconitic beds underlie a large part of the east Texas 

 Tertiary surface sheets. 



These profiles have an important bearing upon the question frequently 

 asked the writer — Why has the great calcareous portion of the Lower 

 Cretaceous so well represented in the Texas region no representation in 

 the North Atlantic or New Jersey area? The sedimentary conditions of 

 the last named region, do occur in Arkansas and may be traced southward 

 to Arkadel{)hia. Stated briefly, the}^ consist of numerous thin, unindu- 

 rated, mostly ferruginous terranes of basal Lower Cretaceous (Potomac), 

 Upper Cretaceous (Glauconitic), Eocene and later littoral deposits. Li the 

 profiles given it will be seen that the deeper water or limestone beds ap- 

 pear to the westward in greater proportion as the land stripping has pro- 

 gressed, and are concealed eastward by the successive overlapping more 

 and more toward the interior of the newer and differently striking shore 

 deposits. The off'-shore limestone deposits of the Cretaceous, if they exist 

 in the New Jersey area, would only occur in that portion of the crust 

 now beneath the ocean. In the Arkansas region the area of littoral depo- 

 sition was constantly repeated, owing to the mountainous barrier. In 

 Texas south of Red river these shorelines had wider room for sweeping 

 and differential overlapping. , 



The beds of the Lower Cretaceous have a slightly different strike 

 away from the Ouachita shoreline than those of the Upper Cretaceous. 

 The individual beds also vary in like composition and sedirnental 

 characters away from the Ouachita shore. 



♦This fact was not appreciated by the writer at the time when his Arkansas report was written. 



