GEOLOGY OF SARATOGA SPRINGS AND VICINITY 95 



they have furnished the great number of fossils, other than grapto- 

 Htes, recorded by the writer in Bulletin 42. Frequently concretions 

 of both limestone and clay are found scattered or more or less 

 obscurely arranged in layers. 



Owing to the extreme pliability of the argillaceous shales and 

 the lack of strengthening intercalations of grits etc., the Snake 

 Hill beds are, as a rule, intricately contorted and crumpled and cut 

 by cleavage planes and smoothed slip planes, until they have the 

 character of the shales which were termed by the geologists of the 

 first survey " glazed " and " semimetamorphic " shales. These 

 shales so designated were Snake Hill shales of the Hudson valley. 

 Yet, localities have been observed, as at the west shore of Saratoga 

 lake, where these shales were distinctly slaty, and near Argyle, just 

 beyond the edge of the sheet, they have been quarried for slate. 



At Snake hill — a picturesque high promontory on the east side 

 of Saratoga lake and an old landmark, suspected by many of the 

 settlers of the region of being an '' old volcano " — the formation 

 has a different character, the shales containing here compact grit 

 and conglomerate beds i to 4 feet thick, consisting of coarse sand- 

 stone with silicious and argillaceous cement and many pebbles, up 

 to I inch in diameter, well rounded and consisting of shale, black 

 limestone, cherty '' white bed " and milky quartz. While the grit 

 and conglomerate beds are bent into recumbent, nearly flat folds, 

 the intercalated shales are intensely crumpled. There also occur 

 thinner beds of gray, crystalline, often sandy limestone. In follow- 

 ing the grit beds along the shore it is seen that they are not very 

 extensive, very irregular in thickness and sometimes replaced in a 

 short distance by shale. All the rocks of this locality, the shales, 

 the limestone bands, the grits and the conglomerates, are fossili- 

 ferous and besides a few graptolites furnish 'cystids, crinoids, 

 brachiopods, gastropods, pelecypods and trilobites. In the shore 

 cliffs of the lake a mile north of Snake hill, lamellibranchs and 

 gastropods occur in association with some of the characteristic 

 graptolites of the formation, and in the Httle disturbed beds of the 

 west shore the graptolites were found in fine preservation in a 

 number of places. 



Only one other outcrop of the conglomerate bed was observed, 

 6 miles northeast of Snake hill. The bed may therefore be len- 

 ticular and of but local extent. Intercalations of silicious shales 

 weathering whitish and of sandstone beds were observed in the 

 section exposed along the road leading southeast from Gansevoort 



