Page:The Habitat of the Eurypterida.djvu/112

 more especially due to difference in origin. The sediment of the Bertie and its fossils came from the continent of Atlantica, and those of the Pittsford from Appalachia. This is more fully discussed in a subsequent chapter (see p. 229).

The Bertie waterlime of Upper Siluric or Monroan age is confined to central and western New York, and the adjacent portion of Ontario, Canada. It is a gray, fine-grained, argillaceous calcilutyte of a remarkably uniform character, showing practically no variation in texture from place to place. Chemical analysis has shown it to be an impure limestone, high in magnesia, silica and alumina. The following analysis is that of an average specimen (39, 101).

A typical section of the Bertie is exposed at Buffalo where Pohlman has recorded the following succession the lower part being obtained from borings. (See also Grabau, 82, 115).