OHIO YALLEY-BALCONES LINE OF DISTURBANCE 545 



Ohio Yalley-Balcones Line of Disturbance 



In the President's address before this Society last year,^ Professor 

 Kemp warns us, and reiterates the warning, that we are never safe from 

 i^aieons rocks. The statement was made in connection with his reference 

 to the row of peridotite dikes which occurs along a line extending south- 

 westward from western New York, crossing Pennsylvania and Kentucky, 

 as far as the dikes in Pike County, southwestern Arkansas. This row of 

 dikes, especially as they outcrop in Pennsylvania and Kentucky, has also 

 been noted by James H. Gardner in his paper published in the bulletin 

 of this Society in 1915,^ in which he calls attention to a practically con- 

 tinuous line of stratigraphic disturbance in the Ohio Yalley, extending 

 from the Appalachian plateau in Pennsylvania to the Ozark Mountains, 

 a distance of over 500 miles. In Pennsylvania and northern West Yir- 

 ginia this structure is known as Chestnut Eidge anticline; in southern 

 AYest Yirginia it is the AVarfield anticline ; in eastern Kentucky it is the 

 Campton anticline ; farther w^est it is the Kentucky Eiver-Dividing Eidge 

 fault ; in western Kentucky it is the Eough Creek uplift, while in Illinois 

 it is the Shawneetown and Bald Hill anticlines. 



While keenly recognizing the fatal fascination of long-distance corre- 

 lation, it has occurred to me that this line of weakness, characterized by 

 faults, folds, igneous dikes, and other earth movements, all of them indi- 

 cations of lines of weakness, might possibly be carried a step further. 



Udden, Baker, and Bose,^ in discussing the Austin-Uvalde occurrences 

 of igneous rocks along the Balcones fault zone, have suggested that the 

 Arkansas dikes belong to the same line of igneous activity. They say : 



"This belt is a portion of a larger belt of igneous activity which extended 

 from the Arkansas River at Little Rock, Arkansas, west-southwestward to 

 beyond the Rio Grande — a belt in which the igneous rocks are characterized 

 by the presence of the minerals nepheline and augite." 



In other words, Kemp ties up the Arkansas dikes to New York, while 

 the Texas geologists tie them to the Uvalde intrusives. The question 

 naturally arises. Who is right ? Obviously, both may be right. The idea 

 that there may be a transcontinental line of weakness, of which the Ohio 

 Yalley disturbance, the Balcones fault zone, and the various igneous 

 dikes are all visible expressions, is therefore presented at this time with 

 the hope that it may invite suggestion and criticism. 



In this connection Mr. Gardner says, in a letter dated December 6, 

 1922: 



XXXVI — Bull. Gkol. Soc. Am., Vol. 34, 1922 



