LIME AND CEMENT INDUSTRIES 7G5 



the Scntella and Oriskany shelf above the Pentamerus escarp- 

 ment below. Its thickness apparently decreases somewhat in the 

 Kingston-Rosendale region, but it retains its characteristics. 



The Pentamerus or lower Pentamerus are the most conspicuous 

 members of the lower Helderberg formation. They give rise to 

 the great escarpment which marks the eastern edge of the Helder- 

 berg formation as it passes along through central l^ew York. 



The beds are mostly hard, massively bedded and vertically 

 jointed limestones. The rock is generally bluish gray in color 

 but weathering imparts a lighter tint to the surface. Partings 

 of slate occur occasionally as well as lenses of chert, specially in 

 the east and south. 



The Pentamerus limestone is a quite uniform member, and its 

 thickness does not vary greatly. " At Schoharie its thickness is 

 between 60 and TO feet, in the Helderbergs it is the same and a 

 trifle more about Catskill, 80 feet according to Davis, 60 feet at 

 Saugerties, 30 to 40 feet about Pondout, 70 to 100 feet about 

 Posendale, the maximum being in the ridge just northwest of 

 the village. The Pentamerus beds are quite sharply demarked 

 from those above and below them.'' 



The finest exposures of the Pentamerus ledges are in the great 

 escarpment of the Helderberg mountains near the Indian Ladder, 

 where they rise in great cliffs surmounting steep slopes to an 

 altitude of 700 feet above the plain lying to the north and east. 



The Tentaculite beds are thin bedded, dark blue limestones,, 

 lying below the Pentamerus beds, and usually constituting the 

 base of the Pentamerus escarpment or lying beneath its talus. 

 The beds vary in thickness from an inch to a foot in greater part^ 

 but two or three inches is the average. 



The Tentaculite beds have a thickness of 40 feet at Howe 

 Cave and Schoharie, somewhat less in the Helderberg mountains 

 and from 30 to 40 feet through the Catskill and Kingston regions. 

 In the Posendale region the amount is less. «. 



There are several outliers of the Helderberg limestone, of 

 which an important one is Becraft mountain. 



