HUDSON RIVER BEDS NEAR ALBANY 531 



Besides this occur: 



Diplog^raptus quadrimucronatus, Hall 



Diplograptus cf. foliaceus, Murchison^ fragments 



Corynoides curtus, Lapworth 



Leptobolus insignis, Hall 



Station 19. Ravine by Normans kill 

 About half a mile farther up the river in a ravine in the south 

 bank a gray, arenaceous and micaceous, thin bedded shale wa« 

 found which yielded quite a number of specimens of D i p 1 o - 

 g rapt us putillus. Hall (station 19). The beds of this, as 

 those of all preceding stations, dip steeply to the east and have 

 been involved in the tilting of the Hudson river beds. 



Station 20. Black creek, Voorheesville 



Following the Normans kill no outcrops are found in its widen- 

 ing valley or along any of the tributaries till reaching Black 

 creek, a small southerly affluent, 4 miles farther up (station 20). 

 The banks and the bed of this creek are formed of dark, often 

 black, soft, non-metamorphic, mostly argillaceous shales, from 

 which the creek derives its name. While near its mouth the 

 shale is slightly disturbed by a fault which, according to its south- 

 west strike, still belongs, as an accessory fault, to the Hudson 

 river system of faults, the shales farther up the creek show a 

 regular n 70° w dip and n 160° w strike, and lie hence outside 

 the easterly tilted block of the Hudson river region. The large 

 fault reported by Emmons and Ford as extending from Saratoga 

 Springs across the Mohawk river and separating the tilted and 

 folded Hudson river region from the undisturbed region to the 

 west, probably passes the Normans kill between the last two sta- 

 tions and may also account for the lack of outcrops and the 

 broadening of the valley between them. These black ehales con- 

 tain : 



Orthograptus quadrimucronatus. Hall sp. 



Diplograptus putillus, Hall 



Climacograptus typicalis. Hall j 



