544 NEW YORK STATE MTSET'^T 



dolomite pebbles become more abundant toward the upper 

 horizons. Dolomite also occurs in thin beds intercalated 

 between the layers of sandstone toward the higher levels, and 

 in the uppermost horizons, as already mentioned under heading 

 2, gradually crowds out the sandstone. In the upper levels 

 frequent beds are composed of nicely rounded grains of clear 

 quartz with little cement, that crumble to a sugary powder 

 under the hammer. Rounded grains of quartz of a slightly 

 larger size occasionally cover the upper surface of a layer 

 of finer grained sandstone, and being without cement, they 

 stand out in relief above the surface with an appearance of 

 having been sprinkled from a pepper pot. In other cases aggre- 

 gations of noncemented grains have been found embedded 

 within layers of heavy though porous beds, as in the case of 

 the Hyolithes bed, 150-A3, in the Ausable chasm. 



5 No fossils have been recognized in the lower portions of 

 the formation. The middle portion has afforded only the 

 Climactichnites tracks at the Birmingham bridge, and numerous 

 irregular, unidentified worm borings and trails. 



The upper portion of the formation holds fossils through a 

 series of beds aggregating at least 350 feet in thickness. We 

 have at present no evidence on the position of these fossil- 

 iferous beds in relation to the actual top of the formation. 

 The list of fossils includes: trilobites, four species; brachio- 

 pods, three species; gastropods, three species; annelids, two 

 species, and several undeterminable burrows and trails; 

 fucoids, several; tracks, one species of Climactichnites. 



To some extent these fossils may be arranged in zones. Such 

 arrangement can only be tentative and will certainly need 

 readjustment with the extension of the field work over a 

 larger area. Two species of brachiopods, L i n g u 1 e 1 1 a 

 acuminata and Obolella prima, seem to occur 

 throughout the entire range of the fossiliferous horizons, as 

 do also the fucoids and many worm trails and branching 

 burrows. 



