64 



SKETCH OF THE 



rock of nearly a similar nature, but which is softer and has a greater 

 proportion of alumina associated with the silica, which last, however, 

 appears to be the most abundant ingredient. This rock greatly resem- 

 bles, in its structure, the fine grained freestones ; but it occurs in strata 

 highly inclined alternating with the other rocks. It is seen passing 

 both into the more compact quartz rocks and the argillaceous schists. 



A very common variety of quartz rock in this district appears in the 

 form of a compact, fine grained rock, — translucent, or translucent at the 

 edges, — of a bluish color, with sometimes a tint of red, and capable of 

 being split into layers of from half an inch to nearly a foot in thickness, 

 and in the deep ravines in which this portion of the country abounds, many 

 sections of the strata of this rock may be observed. From the compact- 

 ness and durability of its structure, — from the regularity of its stratifica- 

 tion, and the nearly vertical position of these strata — the surface of these 

 crags is often perfectly smooth and perpendicular. This variety occurs 

 abundantly in the boundary ranges of the valley, and forms the entire 

 of the hills which skirt the lldayasdgar lake, running south, till it is 

 succeeded by the granitic rocks and gneiss of the neighbourhood of the 

 Dhdbar lake. It is also of very abundant occurrence throughout the 

 whole of the southern portion of the district under consideration. It is 

 the hornstone and columnar hornstone of Captain Dangerfield. 



Ferruginous quartz is also abundant, and the color of this varies 

 from very dark blackish red to a red of a light shade. The quartz rocks, 

 too, sometimes approach to the nature of the millstone grits, and many 

 of them have a tendency to assume, on exposure, a globular form, the sur- 

 face of these exhibiting a concentric laminary structure. This is parti- 

 cularly the case with those varieties which have a small quantity of 

 felspar associated with them. Indeed, these last seem, in many instances, 



