68 



NEW YORK STATE MUSEUM 



Table shov/ing the Lower Cambric series as exposed in Rensselaer 

 county and part of Columbia county, N. Y. 



SERIAL 

 LETTER 



DESCRIPTION OF STRATA 



FAUNA 



ESTIMATED 



THICKNESS 



IN FEET 



H 



G 

 F 



E 



D 

 C 



B 

 A 



Greenish shale 



Thin-bedded limestone, or dolo- 

 mitic limestone, in varying alter- 

 nations with black or greenish 

 shale and calcareous quartz sand- 

 stone. Some of the limestone 

 beds brecciated within the sand- 

 stone or shale and forming brec 

 ciation pebbles, in places, how 

 ever, beach pebbles 



Greenish, reddish, purplish shale, 

 in places with small beds of more 

 or less calcareous quartzite. 



At Troy, in upper part a 2^ foot bed 

 of calcareous sandstone 



Granular quartzite, in places a cal 

 car.eous sandstone 



Olive grit, metamorphic, usually 

 weathering reddish; absent at 

 south 



Greenish, or reddish and greenish, 

 shale with small quartzite or grit 

 beds 



Massive greenish quartzite, in 

 places very coarse 



Reddish and greenish shale with 

 small beds of quartzite or grit 

 (rarely up to 5 feet thick) 



Massive greenish quartzite, in 

 places very coarse 



Reddish and greenish shale with 

 small beds of quartzite or grit, 

 from I to 12 and, rarely, 24 

 inches thick 



Olenellus fauna. 



Oldhamia, 

 trails 



annelid 



Hyolithes and Hyo- 

 lithellus 



Traces of? , 



Casts of impressions, 

 Oldhamia ^ 



Casts of impressions, 

 Oldhamia 



Casts of impressions, 

 Oldhamia 



50 

 « 20-200 



2 5?- 100 + 



10-40 



18-50 



4i 



65-535 



10-50 

 30-80 



8-40 



4 



50-80 



« Usually 50 

 all three. 



^ Oldhamia occurs in A, C, or E, and quite possibly in 

 Minimum, 286. Maximum, 1225 + 



^ 



