LOWEST RED SANDSTONE. 409 



SYNOPSIS OF THE LOWEST (RED) 

 SANDSTONE, 



FIRST DIVISION. 



Simple : of quartz alone. 

 A. Sandstone, of various degrees of hardness. 



a. Fine, arenaceous. 



b. Gravelly. 



c. Compact, splintery, scarcely arenaceous. 



These varieties are comparatively rare. The 

 colour is sometimes white, but it is also occa- 

 sionally reddish, yellowish, or grey ; the quartz 

 itself being coloured : Var. c. is not to be dis- 

 tinguished from quartz rock, except by its con- 

 nections. 



SECOND DIVISION. 

 Compound : of two or more ingredients. 



A. Quartz sand mixed with clay. Argillaceous 

 sandstone. 



a. Gravelly. 



b. Fine, arenaceous. 



c. Very fine, the particles of quartz 



invisible. 



These vary materially in aspect and character, 

 according to the relative proportions of the in- 



