ON CONGLOMERATED ROCKS. 



207 



1. Grey-TVackt, 



This rock is composed of pieces of clay-slate, grey- 

 wacke, flinty, slate, felspar, and quartz, imbedded 

 in a basis of the same materials, or a basis of clay- 

 slate. The pieces or apparent fragments vary in' 

 magnitude, from that of a pea, to much above that 

 of a man's head. It is distinctly stratified, and 

 alternates with clay-slate, limestone, and other 

 rocks. It abounds in the alpine country, to th^ 

 north and south of the Firth of Forth, 



£. Sandstofje, 



This rock is composed of grains of quartz, seldom 

 exceeding a pea in size, connected together with- 

 out any basis, just as quartz concretions are in 

 mica-slate and quartz rocks. 



3. Limestone, 



Conglomerated limestone rocks are not uncommoa 

 in transition country. They at first sight appear to 

 be composed of fragments of limestoiie, imbedded 

 in a limestone basis or ground. Sometii^nes por- 

 tions of compact limestone appear imbedded in 

 granular limestone ; in other instances, portions 



