88 The Lower Devonian DErosixs of Maryland 



are overlain by a great thickness of the latter. It is these physical differ- 

 ences which render it so easy to obtain the fauna of the New Scotland 

 member in New York and so difficult to extract the fossils from the solid 

 cherty limestones of Maryland. The thickness of the New Scotland varies 

 from 12 feet at Tonoloway, where the shale is absent, to 43 feet at Keyser, 

 West Virginia, the limestone beds being 29 feet thick and the shale beds 

 14 feet thick at the latter place. 



Fauna. — The New Scotland member abounds in fossils which are pre- 

 served in great perfection, especially in the chert. The fauna, as far as 

 obtained, is a duplicate of that of New York in nearly all respects. Almost 

 nothing of a local character has been found, but the reason for the rarity 

 of brj'ozoa which are so profusely developed in New York has not yet 

 been ascertained, although the heavy-bedded cherty nature of the lime- 

 stone may account for the scarcity of the latter forms. 



'New Scotland-Coeymans Boundary. — The New Scotland-Coeymans 

 boundary is not so well defined lithologically as that between the Keyser 

 and Coeymans. The lower 4 to 8 feet of the New Scotland contains less 

 chert and is more or less transitional, both lithologically and faunally. 

 At a number of loealties a thin bed of shale is found at the horizon of 

 most rapid change in the lithology and fauna. The base of this stratum 

 has been selected as the base of the New Scotland member where it occurs. 



lite Becraft Member 



Character and Thickness. — In the early days of American geology, 

 this division was known as the Upper Pentamerous limestone and also the 

 Encrinal or Scutella limestone. Together these, compose the Becraft lime- 

 stone, so named by Barton'' from Becraft Mountain an outlier of the 

 Helderberg rocks on the east side of the Hudson Eiver, a little south of 

 Hudson, Columbia County, New York. The Becraft represents the clos- 

 ing stage of the Helderberg. In Maryland this member is an arenaceous 

 limestone interbedded with much black chert. It occurs only in Washing- 

 ton County. Its thickness is about 85 feet. 



Fauna. — The Becraft member contains an abundance of organic re- 

 mains, as yet not exhaustively collected. The guide fossil is Rensselceria 



' 13th Ann. Kept. N. Y. State Geol., 1894, pp. 245, 246, 304. 



