• 834: NEW YOKE STATE MUSEUM 



sample gave quite a plastic mass, with 21^ of water. The air shrink- 

 age was Sfo. When heated to .06 the total was 4^ with incipient 

 fusion, and the color deep red. The clay vitrifies at 1, with a total 

 shrinkage of 7^. The shale has .2^ soluble salts. 



'No. 5 of Bishop is also from near Windom. It is a fine-grained 

 shale, which worked up to a lean mass with 19^ water. Tensile 

 strength, 35 pounds a square inch. The air shrinkage was 3^. At 

 .03 the total shrinkage was 7fo, and the bricklet was nearly vitrified. 

 It was completely vitrified at 1 with 9^ shrinkage. It became vis- 

 'Cous at 5. The soluble salts were .35 fo. Its composition is: 



Silica 61.15 



Alumina -. . . . 14 . 57 



Ferric oxid Y . 20 



Lime 3.06 



Magnesia .20 



Alkalis 1.90 



Water 5.95 



94.03 



Portage. (^See Hall. Geology of the Wh district of New YorJc. p. 

 224.) Another important shale occurs in this member of the Devon- 

 ian formation. The group consists of a lower shaly member, the 

 Cashaqua shale, a middle member of shales and sandstones, and 

 an upper one of sandstones. 



The Cashaqua shale is exposed along Cashaqua creek, where it is 

 a soft green shale that weathers to a tough clay. It also occurs along 

 Seneca lake and at Penn Yan, but east of this becomes very sandy. 

 Good exposures are seen along Allen's creek and Tonawanda creek, 

 and the branches of Seneca and Cayuga creeks. On Lake Erie at 

 Eighteen Mile creek it is 33 feet thick, while along the Genesee 

 river it is 150 feet thick. 



Concerning the Gardeau shales, Prof. Hall states that they 

 are exposed along the Genesee river, where the section involves al- 

 ternating layers of shales and sandstones. Toward the east the 



