REVIEWS 675 



of a few Mesozoic formations in South Africa, are Paleozoic in both cases, 

 and were originally spread out in horizontally uniform sheets of great vertical 

 diversity. Great thicknesses of rock were laid down on slowly subsiding 

 peneplains until compressional forces crowded them into parallel folds 

 with overturns directed toward the continental center and with essentially 

 flat plateaus on the landward side of the systems. In both cases, therefore, 

 the mountain-making forces produced thrusts directed from the ocean 

 toward the land masses. The massive Karroo formations in southernmost 

 Africa, as the Carboniferous strata in the Appalachians, have been almost 

 entirely removed from the folded area by a long period of erosion, which 

 produced a partial peneplanation; while the renewal of deep erosion since 

 that period is the result of another relative uplift. The present configura- 

 tion of the mountains is in no sense due to the form the country received 

 originally as a result of the action of the compressional forces, though the 

 prevalence of anticlinal ridges and synclinal valleys has proved a snare to 

 some observers. The synclinal valleys are occupied by resequent, not 

 consequent, streams; the early consequent streams were diverted to the 

 anticlines at one period, but were forced back into synclinal positions by the 

 resistance of a second deep-lying hard stratum. Where the beds of a regu- 

 larly folded region are of great vertical diversity and the geologic history is 

 similar to that of the Alleghenies or the Cape Colony ranges, the resequent 

 type of valley is the one which theoretical considerations indicate as the 

 natural result of the conditions prevaiUng. H. H. 



Drainage Modifications in the Tallulah District. By Douglas 

 Wilson Johnson. Proceedings of the Boston Society of Natural 

 History, Vol XXXIII, No. 5; pp. 211-48. Boston, February, 

 1907. 



The Chattooga River flows southwest between Georgia and South 

 Carolina to the westernmost point in the latter state, where it receives the 

 Tallulah River as a tributary from the northwest and then turns abruptly 

 to the southeast and flows to the Atlantic Ocean under the names of the 

 Tugaloo and Savannah rivers. A few miles from this abrupt bend. Deep 

 Creek, one of the headwaters of the Chattahoochie system, continues the 

 course started by the Chattooga to the southwest. 



The conclusion is reached that, by a process of "remote capture," the 

 Chattooga River, which formerly flowed southwest into the Gulf of Mexico 

 as a part of the Chattahoochie system, was captured by a member of the 

 Savannah system. The Atlantic drainage gained this victory over that of 



