DESCRIPTION OF THE FORMATIONS. F\ 51 



scanty it is true, but quite satisfactory, of the persistence 

 of a characteristic Clinton fauna with the Sand-vein ore bed. 

 Here however the Clinton fauna, pure and alone, ceases. 



Above the Sand-vein ore (or limestone) comes a mass of 

 green shale and thin hard limestone bands in which fossils 

 are scarce, but from which. I have obtained two or three 

 species. Among these are Lingula oblonga, Hall, found 

 in the Clinton group of New York and Beyrichia notata, 

 Hall, described from the Lower Helderberg of that State. 



There are also some Lamellibranchs not yet determined. 



We have here therefore a mingling of the Clinton and 

 Lower Helderberg faunas indicating passage beds from the 

 one system to the other, such as should be looked for at all 

 such changes of horizon. The commingling of species is 

 limited, so far as my observations have gone, to the belt of 

 green shales and limestones here mentioned. 



Immediately above comes the Bloomsburg Red Shale which 

 is almost barren. Only in one or two places has it yielded 

 any fossils that bear upon this question, and those two are 

 the well-known Lower Helderberg forms, Beyrichia notata % 

 Hall, and Leperditia alia, Conrad. No Clinton form has 

 yet occurred. 



Paleontology therefore fully bears out the proposed sep- 

 aration of No. V of Rogers thus : — 



Onondaga group, Bloomsburg red shale. (See Report G 7 .) 

 Passage beds, Green shale and limestone. 



/ Sand-vein ore bed. 

 Ore, sand-rock, and fossil ore. 

 Upper green shale and fossil ore. 

 Iron sandstone. 

 | Hard fossil block ore. 

 I Lower green shale. 



Clinton group, ^ 



These beds are thus correlated with those of the First 

 Survey of Professor Rogers, (Vol. 1, p. 132.) 



Onondaga, Bloomsburg red shale, Surgent Red shale. 



Passage beds, Green shale, " Upper shale. 



( Ore sand-rock, " Ore sandstone. 



Upper green shale and ore, \ " Lower shale ' 

 Clinton, | B ) « Upper slate. 



i Iron sandstone and ore, " Iron saruNtone. 



L Lower green shale, " Lower slate. 



