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NEW YORK STATE MUSEUM 



(13) Port Ewen shaly limestone. The beds below those noted 

 in the preceding paragraph are essentially argillaceous, shaly lime- 

 stones. They vary from rather massive to thin bedded, are dark 

 grayish in color, and have a peculiar nodular or concretionary de- 

 velopment along certain sedimentation lines. These spots have less 

 resistance to weather than the surrounding rock and therefore 

 develop rows of pits along the face of an outcrop. Their size, 

 6 to 18 inches or more across, together with their persistence makes 

 an easily recognized physical feature. The few fossils that are 

 found are not very characteristic. The following should be men- 

 tioned : Spirifer perlamellosus. 



In the discussion and on the maps the Port Ewen and Oriskany 

 are treated together as a single unit as the Oriskany-Port Ewen 

 beds. 



(14) Becraft limestone. Massive, heavy to thin bedded, light 

 colored, semicrystalline to thoroughly crystalline limestone. More 

 massive beds very pure, 94 + /^CaCOo. Shaly beds resemble the 



New Scotland which they pass 

 into at the base. The most char- 

 acteristic features for field iden- 

 tification are (a) pink or light 

 colored spots, (h) a more 

 coarsely crystalline condition 

 than any of the associated strata. 



(0 



occasiona 



1 lar2'e calcite 



Fig. 4 Sieberella pseudogal- 

 e a t a Hall, the most characteristic index 

 fossil of the Beacroft limestone of the Ron- 

 dout region , 



cleavages to be seen wherever 

 a fossil crinoid base A s p i d o - 

 crinus scutelliformis 

 is broken, {d) the very charac- 

 teristic fossil Sieberella 

 pseudogaleata, and {e) many crinoid stems. 



The formation carries many fossils in addition to those given 

 above, among which are Spirifer concinnus, Uncin- 

 ulus c am p b e 1 1 a nu s . 



(15) New Scotland shaly limestone. Thin bedded, dark gray to 

 reddish sandy and shaly limestones. The rock breaks out in slabs 

 on weathering and develops red iron stains. It has especially 

 abundant fossils, the most characteristic of which are : O r t h o - 

 thetes woolworthanus, Spirifer macropleura. 

 Other common ones are: Leptaena rhomboidalis, 

 Strophonella headleyana, Ripidomella oblata, 

 S t r op h e o d o n t a becki. 



