The Geology of the Lower Leigh Valley. 55 



increased. From the escarpments higher up the river many 

 additional forms have also been collected. Moreover, some 

 important revision work has been lately done by various palaso- 

 conchologists, and a greatly extended, as well as revised, list of 

 fossils is herein submitted. 



Eocene Beds. 



In discussing these, it will be most convenient to commence 

 wi,th that at the Red Bluff (Sec. II.), which is the best known 

 and by far the richest of the fossiliferous outcrops on the river. 

 As stated in our previous notice of it, the fossils on the exposed 

 face adjoining the river show only for about 50 feet from the 

 water's edge, but a rubbly decomposed limestone can be traced 

 to a farther height of 100 feet; that is, within 40 feet of the 

 level country at the top. On the northern face of the bluff the 

 limestone is occasionally hard and compact, but fossils in it are 

 exceedingly scarce. Much of the hill is masked by ii'onstone and 

 basaltic boulders fallen from above — so much so, indeed, that on 

 a cursory inspection one is apt to regard the basalt as a much 

 thicker deposit than it really is. Above the limestone, at the 

 spot where the section was measured, there is about 15 feet of 

 ironstone conglomerate (miocene), which passes directly under 

 the capping of basalt on the summit. The section is therefore — 



Basalt ... ... ... ... 25 feet 



Miocene conglomerate ... ... 15 ,, 



-P, ( Rubbly lime.stone ... ... 100 „ 



I Fossiliferous clays ... ... 50 ,, 



Total ... 190 feet 



Erosion of the eocene surface prior to the deposition of the 

 miocene is evident enough, not only here, but in other sections 

 to be quoted, and the younger rock has apparently filled in 

 depressions in the older ; thus, a few yards to the west of the 

 measured section, miocene boulders were seen cropping out from 

 ten to fifteen feet lower down the hill. On the other hand, where 

 the junction of the miocene with the basalt is visible on the bluff, 

 the latter rock rests horizontally upon the levelled off surface of 

 the former. 



