FAULT SYSTEMS OF THE HEGION. 313 



interior strike throughout Arkansas, Indian Territory and Texas, and it 

 belongs to the phenomena discussed by McGee under the head of " The 

 Lafayette Formation."* The position and history of Red river during 

 this epoch have not been determined. All the terraces, benches and 

 wide bottom lands lying above the present Red river and the wide flood 

 plains are called "second bottoms." It would be just as appropriate to 

 speak of the third, fourth and fifth bottoms in some cases, for the so- 

 called bottom phenomena do not represent a single epoch of baseleveling 

 and deposition, and for the j)resent we class them together and lay them 

 aside for future investigation to interpret. 



These alluvial deposits and their wide eroded valleys occupy a large 

 proportion of the country and in some instances extend fifteen miles 

 from the river. They are not only developed in Red river, but they 

 especially characterize all the northward laterals flowing down from the 

 Ouachita mountains. Together with the timbered Trinity valley they 

 surround the quadrangular gravel plateaus of Arkansas and Kiamitia 

 prairies with belts of lower timbered valleys. 



The second bottom formations of Red river and of Sulphur fork unite 

 in the easternmost Texas county and send wide prolongations up their 

 respective streams. As we go westward the Cretaceous prairies begin to 

 appear in the angle between them, gradually increasing in proportionate 

 area to the westward as the second bottom phenomena diminish. 



Fault Systems and their Influence on Topography and areal 



Geology. 



The northwest and southeast faulting mentioned has greatly influ- 

 enced the areal distribution of the formations and especially in the 

 eastern portion where the rocks are mostly of an unconsolidated char- 

 acter. I have previously described f a great line of faulting with a 

 northeast-and-southwest strike and an eastern downthrow known as the 

 Balcones system, which extends from the Rio Grande northeastward via 

 San Antonio, Austin, Bel ton and Dallas toward Red river, and probably 

 crosses into Arkansas. It would be represented on the east border of 

 the map west of where the Arkansas-Choctaw line touches Red river. 

 This system of fiiults, the writer believes, crosses the area under dis- 

 cussion through the unconsolidated beds, but it is difficult to locate 

 them where the consolidated rocks are unexposed. 



The Red river system of faults, however, strike at right angles to 

 the Balcones system and apparently crosses it in the central Red river 



* 12th Annual Report U. S. Geological Survey. 



tTexas Section of American Ci'etaceous: Am. Jour. Sci„ October, 18S7. 



XLIII— BuLt Gkol Soc, Am,. Voi,. 5, 1893. 



