42 



DESCRIPTIONS 



lar gypsum^ laminated selenitej anhydrous gypsum, Jluor spar 

 in limpid cubes, arragonite, dog-tooth spar, brown spar, 

 and waxy hJende. Galena has been found in small masses 

 imbedded in this rock, and bitumen has been observed in ex- 

 udations upon its surface, and in geodes. 



17. CoRNiTiFEROus LiMEROcK,* consists of carbonate of 

 lime, embracing hornstone. Subdivisions. Compact, when 

 the rock is close-grained ; and it generally contains hornstone 

 in layers. Shelly, when it consists of shells and contains 

 hornstone in nodules or irregular masses. 



Localities. Black Rock affords an excellent locality of the 



Extends up , * , i i • i i 



the lakes, compact, and Auburn, behmd the state prison, presents a most 

 perfect locality of the shelly. This stratum has been traced 

 from Lake Erie to the Helderberg in Albany county. It has 

 been traced up the Cayuga and Seneca lakes ; and, from the 

 head of the latter, up Catharine Creek, by Engineer Hughes, 

 But it has not been traced under the Tioga coal beds ; though 

 Mr. Hughes found it at a level, which seemed to demonstrate 

 that it must run several hundred feet beneath that formation. 



Underlays Possibly it may unite with the cherty limerock, which forms 



Tioga coal. j j j -> 



the upper surface of the metalliferous limerock, and which un- 

 derlays the Carbondale coal. If so, the anthracite of Carbon- 

 dale and the bituminous coal of Tioga, are in the same carbo- 

 niferous formation. However, these strata are certainly sepa- 

 He?de!ber°- ^^^^^ gr^ywacke rocks at the Helderberg in Albany coun- 

 ty, several hundred feet in thickness. See both profiles in the 

 map ; particularly the exhibition of the cuneiform termination 

 of strata. 



Class IV. JJpper Secondary, or Fourth Series, 

 4. Carlo- Third Graywacke, is an agsrefrate of grains of quart- 



madoa. zose sand, less angular than those of first and second gray- 

 wackes, and generally contains fine grains of limestone ; and 



* I rfirret that 1 introduced this name. I had not then seen the name Cheriy 

 limerock applied to this stratum. Dr. Bixby has very properly applied it to 

 this very rock ; and Bakewell applies it indirectly. Lut cherty does not apply 

 accurately to the compact kind. 



