420 



CHARLES EMERSON PEET 



lower part is blue. Bands and blotches of yellow often occur in the 

 midst of the blue layers in the Hudson Valley. The clay often con- 

 tains concretions. In thickness the clay varies from a small amount 



Fig. 2. — Showing joint structure in the laminated clay of the Hudson Valley. 



to 215 feet in the valley of the Hackensack and zero to 243 feet' in 

 the Hudson Valley, where it is commonly 80 to 100 feet or more thick. 

 In the Champlain Valley it is known to have a thickness as great as 

 60 to 75 feet, but is generally thinner than in the Hudson Valley. 



I H. RiES, Bulletin N. Y. State Museum, Vol. Ill, No. 12, p. 184. 



