694 



SYDNEY H. BALL AND MILLARD K. SEALER 



These gouges occur level with the contact elsewhere, and do not 

 resemble any river-worn scratches with which we are familiar. 

 The grooves, crescentric gouges, and the finely striated planed 

 surface appear to be of glacial origin, and indicate that the glacier 

 once extended to at least this point, or to 4° south latitude. The 

 glacier, from this evidence, advanced from south to north. 



ERRATIC BOWLDERS 



In the immediate Lualaba and Luama valleys in the Maniema, 

 and for several miles on either side between Nyangwe and the 



CROS5 SECTION 



CROSS SfCTION 



A. 



Fig. 4. — Probable glacial grooves and scratches on Paleozoic slaty quartzites, 

 Piana Mulambo Waterfall, Lualaba River. 



5th parallel south, the shale of the Lubilache has sparsely and 

 irregularly scattered through its mass, pebbles and bowlders with 

 a maximum diameter of five feet. These bowlders are not known 

 to occur within the large areas of the Lubilache away from these 

 rivers. They are usually well rounded, and consist of granites, 

 quartzites, diorites, and other older rocks. There is in no case 

 any change in the fineness or character of the well-laminated shale 

 immediately surrounding these isolated bowlders. 



