546 



C. N. GOULD CRYSTALLINE ROCKS OF THE PLAIXS 



"Since the New York-Pennsylvania-Kentucky zone is so long, and since the 

 other zone is correspondingly long, and since the two are more or less lined 

 up, it certainly does look like it jna.j be a transcontinental feature. 



"The Ozark region of isostatic adjustment could easily be an area related 

 to it or a swell on it. The Ozark uplift being a long time in isostatic equilib- 

 rium, at a later period this long diastrophic disturbance could easily be an 

 expression of adjustment running from Appalachian folding (recurrence) 



FiGfRE 2. — Relation of hypothetical Balcoyies-Arkansas-Ohio Yalleif Line of Weakness, 

 to adjacent Mountain Masses; also Exposures of igneous Rock 



down across the Cincinnati uplift and across or adjacent to Ozark uplift and 

 on down east of Llano-Burnett into Mexico. I recall an expression of Cham- 

 berlain to this effect : 'diastrophism works against isostasy,' which is worth 

 thinking about in this connection." 



Professor Kemp, however, is inclined to be rather cautious in this 

 correlation. In a letter December 12, 1922, he says : 



"I have never attempted to plot in detail the peridotite dikes of Arkansas, 

 nor have I ever in my own mind connected them with the Balcones fault zone 

 of Texas. . . . This is also true of the others from this region clear through 



