.nkw rOBS B MUSEUM 



inches, and the white calcite of which they consist contrasts 

 Btronglj with the light bluish gray of the containing limestone. 

 In the Schoharie region where these cups characterize the lower 

 beds of the member, the overlying layers have been called the 

 upper Pentamerus beds from the fossil 1*. p s e u '1 o g a leal us 

 which they contain, and this name has been employed to soi 

 tmt to comprise all the 1 eds. In the eastern extension of the for- 

 mation the distinction is lost. About Cat-kill, Davis designal 

 the lower layers the " Encrina] " and the upper layers the " upper 

 Pentamerus" limestone. Owing to the inappropriateness of the 

 name Scutella and the varying significance of the other names 

 that have been employed, the geographic name of Becraft lime- 

 Btone has been suggested to me by Prof. Hall. The name is from 

 Becraft mountain in Columbia county, where the rock is typically 

 develo] The Becraft limestone has a thickness of 10 to 15 



feet near Schoharie, and the amount does not vary greatly east- 

 ward to the Helderberg mountains and by Clarksville, Aquetuck 

 and ( Oxsackie. Thence it increases rapidly, and Davis reports 

 a thickness of 120 feet below Leeds, the npper 10 feet consisting 

 of impure and sandy or shaly layers. There are, as Davis sug- 

 T s, many local slips in this section, and my estimate of the 

 thickness of the purer limestone would be about 60 feet. 



" Tn the Bondout region the Becraft limestone is 40 feet thick 

 and the upper shaly beds 100 to 150 feet thick. In the ridge just 

 <-;i~t <>f AVhiteport there are 30 feet of Becraft limestone." About 

 Rosendale and southward no exposures have been noted by 

 Darton. "Underlying the Becraft limestone throughout are the 

 h»wer shaly beds, consisting of thin bedded, impure, highly fos- 

 Biliferous limestone with some shale beds." At some localities 

 though, as for instance westward on the Fox kill above Gallup- 

 ville, it is in greater part a massive, relatively pure limestone. 

 In Greene and Ulster counties it has the character of the upper 

 shaly beds, with a more or less slaty cleavage and outcropping 

 in ragged ledges, in some cases closely resembling the lighter 

 col., red outcrops of the Esopus slate. Its thickness from Scho- 

 harie eastward is about s <) feet, and there and elsewhere in the 

 great Helderberg escarpment it constitutes a steep slope between 



