84 Bepoet of the State Geologist. 



Salina Group. 



The tract of country north of the valley of the outlet (Seneca 

 river) is within the outcrops of the Salina or Onondaga salt 

 group, f?rd eir^bra??3 abcnt one-hrif of the width of its exposure. 



This group was divided by Prof. James Hall (Report Geology 

 N. Y., 4th District, 1843) into four sections, viz , 1, and lowest, 

 red shale of Wayne county ; 2, green and ashen marl with small 

 quantities of gypsum; 3, gray or ash-colored marls and shales, 

 with thin-bedded shaly limestones, usually of the same color, 

 containing gypsum and salt beds ; 4, silico-argillaceous limestone 

 or cement-rock. ISTos. 1 and 2 are not seen in the county ; I^o. 3 

 is seen in Black Brook (Tyre) and at Seneca Falls; No. 4 at 

 Seneca Falls at two points. 



The exposures in Black Brook contain only the third variety. 

 A short distance south of Tyre Center it forms the bed of the 

 creek for a considerable distance, with one cliff 15 feet high. 

 The rock is in rather firm slabs of the usual grayish tint. 



The most important exposures are at Seneca Falls along both 

 sides of the canal east of the village, where it forms cliffs 20 

 feet high. In many places the face of .the cliffs displays the 

 peculiar method of quarrying for gypsum, by gouging into the 

 rock to secure the lumps of the mineral. Much of the rock has 

 in late years been taken out to lay on the roads, where it forms 

 a solid bed in summer, but in wet weather " turns to slush." 



The gypsum is found in the lower part of the cliff, forming 

 irregular whitish masses ; there are also thin seams of satin spar 

 and minute crystals of selenite. The shale in which it occurs is 

 of a grayish drab color, weathering into small pieces with a 

 dusty look. The upper layers are more solid, but they have 

 become softened by weathering and break readily in irregular 

 bits. They contain small narrow cavities arranged horizontally. 



The best exposure is found on the south side of the canal, west 

 of the cemetery, where an unusual dip of 5°-10° exist. Here 50 

 feet may be exposed, beginning with the layers already described 

 and closing with some i 5 feet of rock belonging to the upper or 

 fourth division, the cement-rock. This is in part a slab- shale, but 

 there are thick courses which fracture irrespective of bedding 

 and expose fine conchoidal surfaces. The rock is very tough and 

 rings under the hammer ; it is an argillaceous limestone, dark 



