GEOLOGY AND GEOGRAPHY OF THE OLAY DEPOSITS 495 



As will be seen from the above statement bricks are the chief 

 source of income. That the other branches of the clay industry 

 are not further advanced is probably due in a large measure to 

 the fact that the clay deposits of the State have been so little 

 exploited or otherwise examined. Though many of the deposits 

 have been opened up and are still being worked, there are numer- 

 ous others scattered over the State which are still untouched. 

 Few of the clays are found to be of sufficiently refractory char- 

 acter to be used for making fire brick, gas retorts, or other prod- 

 ucts which in use are subjected to a higher degree of heat ; but 

 for the manufacture of coarse pottery, terra cotta, paving brick, 

 etc., many of the clays are eminently suited. 



Within the last seven or eight years the manufacturers in New 

 York have turned their attention toward the extensive beds of argil- 

 laceous shale which the State contains, and which on trial have 

 given very satisfactory results. Several large firms are using them 

 for the manufacture of sewer pipe, terra cotta paving brick and 

 roofing tile. The shale formations at present used are the Salina, 

 Hamilton and Chemung. The Hudson River shales are no doubt 

 sufficiently argillaceous over many areas to be used for the manu- 

 facture of cla}^ products, and the same may be said of the Niagara 

 shale, which weathers to a red clay. A sample of this latter 

 shale from Niagara Falls was first ground and then molded in a 

 stiff mud machine and found to burn to a white brick, which was 

 unaffected by a temperature of 2,500 degrees. 



That the clays and shales of ISew York are comparatively 

 undeveloped is, no doubt, largely due to the lack of knowledge 

 of their extent and character. There seems, however, to be no 

 reasonable doubt that they will in future become a valuable 

 source of revenue. 



GEOLOGY AND GEOGRAPHY OF THE CLAY 



DEPOSITS. 



Deposits of clay occur in nearly every county of New York. 

 They belong to three geological periods, namely : 



Quaternary, Tertiary and Cretaceous. 



The clays of the first age are by far the most common. Those 

 of the second are somewhat indefinite in extent, but they probably 

 include a large number of the Long Island deposits. Of the 



