220 ASHLEY — GEOLOGY OF ARKANSAS. [May 13, 



Permian times) flowed westward, but it has been reversed and 

 now flows east and southeast. 



VII. The igneous rocks of Arkansas and Texas are mostly along 

 what appears to be the edge — possibly faulted — of this depression. 



I have not thought it necessary to exclude or suppress in the 

 present paper statements in conflict with other publications made 

 by the Geological Survey of Arkansas. Reference is here made to 

 the diff"erences between the structural details as worked out by Dr. 

 Ashley and those represented by Dr. Theodore B. Comstock on the 

 map accompanying his report on gold and silver. No geologist 

 with the two maps before him can have any doubt about which is 

 right. It should be said, however, in defense of Dr. Comstock, 

 that the time he could devote to the study of the region on which 

 he had to report was very limited ; and in defense of the publica- 

 tion of his map, that the report giving the economic results of his 

 work (and these were correct and of great importance) was so tied 

 to the theory of the structural lines put down on his maps that it 

 was quite impossible to separate the two. 



John C. Branner, 

 Formerly State Geologist of Arkansas. 



I. Geologic and Geographic Position. 



If in any of the Atlantic or Gulf States, one start from some 

 point on the coast and travel inland, he will, in most cases, observe 

 at one point a striking change both in the topographic and geologic 

 features of the land. He has been traversing at first low-lying, then 

 somewhat more elevated, stretches of level country, characterized, 

 aside from its low elevation above the sea level and comparative 

 flatness, by sluggish, meandering rivers, a luxuriant timber growth, 

 the softness and horizontality of the rocks, consisting of unconsoli- 

 dated clays, sands, gravels, etc., with an occasional hard layer, and 

 by the freshness of the fossil remains. But as one passes the point 

 mentioned, he comes upon a region of higher altitude, frequently 

 or generally mountainous, with rapid rivers, more hardy but less 

 dense timber growth, the underlying strata being highly consoli- 

 dated, frequently crystalline limestones, sandstones, shales and 

 granites, in some regions horizontal, in others highly folded and 

 distorted. 



A study of the geology on either side of the line of division 

 shows that the region on the coast side is of comparatively recent 



