﻿1 60 SMITH. 



to 65°. These sandstone beds alternate with thin seams of shale, of 

 from 2 to 6 inches in thickness. The sandstone is of a dirty-brown color, 

 while the shale is more of a buff ; both the sandstone and the shale appear 

 to be unfossiliferous, as a diligent search for fossils was unrewarded 

 even by the poorest cast or fragment of a shell, or of vegetable matter. 

 There also appeared to be no conglomerate between the sandstone and the 

 underlying serpentine, nor was any indication of contact metamorphism 

 visible. 



The resemblance between this sandstone and some phases of the San 

 Francisco formation in the Coast Range near San Francisco at once 

 impressed me; however, from this we need not argue any close connection, 

 save that the sediments originated from the degradation of similar rocks. 



I have called this formation Bangui Sandstone because of its typical 

 occurrence near that pueblo, where however, it is exposed in a more hori- 

 zontal position, in a great cliff of 50 feet or more. 



Pasuquin arenaceous Limestone Formation. — An arenaceous limestone, 

 dipping on the average of 25° to the east and southeast is encountered 

 in going across the river at Pasuquin in a northeasterly direction; the 

 trail up the hill approximately crosses the strike of the beds the outcrops 

 of which form a succession of small terraces or steps. 



The only indications of fossils which I encountered were a series of 

 snake-like markings which strongly resemble similar infpressions in the 

 Cambrian sandstone. However, some of these in the Pasuquin formation 

 are larger than any the writer has yet seen, in some instances they are 

 nearly 2 inches in diameter and several feet in length. Several small 

 casts of what I believe to be Pteropoda were found; in fact one of these 

 is unmistakably a species of Cleodora. 



I am told by Mr. Burdette, who knows this country perhaps better 

 than anyone else, that this formation can be followed in a semicircular 

 course all the way to Bangui, with the igneous mass to the left and the 

 sedimentaries to the right. 



The Negra Tuff and Ash beds. — Two of the most conspicuous points 

 scenically as well as geologically along the entire north coast of Iloeos 

 Norte are Pnnta Negra, and Punta Blanca which is very close to the 

 former. Exposure of beds of tuff, sandstone and shale alternating occur 

 at these two points. I estimated the cliff of Punta Blanca to be 150 

 feet high, a sheer wall, the beds being approximately horizontal. A short 

 distance to the east, opposite the place where the manganese is being 

 opened up, these same beds are tilted at a high angle. (PL X, fig. 12.) 

 Below is a sketch of the exposure along this part of the coast : 



