229 



observed, arc vertical ; and it is obvious that tlicrc is room for 

 not more than half of the conglomerate series between the 

 mela{)hyr on the southeast and that on the northwest. The 

 lower beds, from the melaphyr (2) and the great conglomerate 

 (3) to the third conglomerate (7), are clearly continuous. 

 Hence there can be but little doubt that the missing beds 

 belong in the uj)])er half of the section, or that their absence is 

 due to a great fault which has elevated the melapiiyr on the 

 northwest. The map represents the melaphyr between the 

 conglomerate series and the granite as broadening rapidly 

 toward the northeast, and this would seem to indicate a 

 marked flattening of the dip. Outcrops are wholly wanting, 

 however, south of Lincoln Street and east of Hawke's Lane ; 

 and it now seems much better that this ai'ca should l>e 

 colored as granite. But even then there would be a decided 

 increase in the breadth of the melaphyr east of the lane. 



The steep monocline can not be traced beyond Unit's Cove 

 Lane. The first one of the two transverse faults represented 

 here appears to be justified by the offsetting of the strata as 

 seen in the actual ledges ; and it is probably less important 

 than the other, which is based upDii the general interruption of 

 the outcrops and especially upon the fact, that to the eastward 

 of this line, so far as the scattering ledges allow us to judge, 

 an entirely different type of structure prevails. The dips, of 

 both the melaphyr and the sedimentary rocks, are everywhere 

 low and indicate broad shallow folds. In the absence of 

 outcro[)s immediately east of the north end of Huit's Cove 

 Lane, we can not know whether this change takes place 

 abruptly or gradually, by faulting or otherwise ; but the fault 

 line on the map calls attention to the fact that a change 

 occurs somewhere in that vicinity, and it also makes it easier 

 to interpret the outcrops along the line of Lincoln Street east 

 of Huit's Cove Lane. 



The melaphyr south of Lincoln Street and west of Thaxter 

 Street, at the northern base of Squirrel Hill, is mostly 



