GEOLOGY AND PALEONTOLOGY OP THE SCHOHARIE VALLEY 



155 



These facts point to an hiatus or stratigraphic unconformity 

 between the Becraft and the Oriskany, which may be due merely 

 to nondeposition in the Schoharie and Helderberg region, without 

 much erosion of previously deposited rocks. 



The Becraft, though a very good limestone, is quarried only in 



two places in the Schoharie valley. One is on the slopes of East 



hill on the road which leads up the hill northeast from Schoharie 



[map : XI g, 44], and the other about half a mile east of Frisby's 



mills in a field between the Middleburg road and the railroad 



track [map: IX j, 62]. 



Fossils of the Becraft limestone 



While this limestone is almost entirely composed of fossils, the 

 number of species is limited. The crinoids are mainly repre- 

 sented by Aspidocrinus scutellif ormis, of which 

 only the broad, shieldlike base is preserved. This is very abun- 

 dant in the lower Becraft and the upper Xew Scotland, for 

 which reason this portion of the formation was formerly called 

 the Scutella limestone. This fossil varies from one to two inches 

 in diameter, and in convexity, from low-rounded to subcorneal. 

 It is always crystallized and the calcite cleavage is a very 

 characteristic feature. 



The brachiopods are the most characteristic fossils of this 

 horizon. Among the orthid shells Schizophoria m u 1 1 i - 

 striata [fig. 69] Avith its strongly convex valve, and sharp, 

 fine surface striae, predominates. Spirifer c o n c i n n u s 

 [fig. 70] is generally represented by small individuals with faint 

 rounded plications and shallow rounded sinus. It is the only 

 common species of the genus. On large specimens the fold of the 

 brachial valve shows incipient plications. The rhynchonelloid 

 shells are represented by Stenoschisma f o r m o s u m [fig. 

 53] already noted in the Xew Scotland ; W i 1 s o n i a vent r i - 

 cosa [fig. 71], a small round, extremely ventricose species, 

 wii li low rounded plical ions ; U n c i n u 1 us c a m p be 1 1 a n n s 

 [fig. 72] and U . nob i li s [fig. 73] easily distinguished by their 

 form and plications. Meristella princeps [fig. 57] 

 and Airy pa reticularis [fig. 38] also occur in this 



