14 A POPULAR SKETCH OF THE GEOLOGY 



line, then, is called the anticlinal line, the beds inclining downwards 

 from it on either hand. The amount of their inclination varies, but 

 it is frequently as much as sixty or seventy, and I never saw it less 

 than twenty-five, degrees. 



SlENITE. 



In describing the aqueous, or stratified, rocks, we have seen two 

 kinds of igneous rocks associated with them, namely basalt with the 

 coal measures at Snibston, and porphyry with the slates of Charnwood 

 Forest. There is yet, however, another igneous rock, which makes a 

 conspicuous feature in the country, but is not so intimately associated 

 with any aqueous rock as to admit of being described with it. This 

 is the sienite, or granite as it is commonly termed, from which in- 

 deed it differs only in the scarcity or absence of mica. The sienite 

 occurs in detached hills round the outskirts of Charnwood Forest, at 

 Mount Sorrel, Grooby, Markfield Knoll, Cliff Hill, and in Bradgate 

 Park ; it also protrudes above the new red sandstone, a few miles 

 South of the Forest district, forming the hills of Enderby and Croft, 

 and being visible near Narborough, at Burrow Hill near Potter's 

 Marston, at Stoney Stanton, at Sapcote, and probably at some other 

 spots with which I am not acquainted. It becomes a question of 

 some importance to determine how far this latter group is connected 

 with that which fringes the south of Charnwood forest. If (as I 

 have been informed) the sienite was reached at the depth of eighty 

 yards, in a boring that was made near Kirby Muxloe, it would go 

 far to prove that there is a connected sienitic ridge running across 

 the county, beneath the level beds of new red sandstone, the higher 

 peaks of which only appear at the surface at different places. It is a 

 fact, however, that the type of the southern group differs materially 

 from that of the northern, being less granular and crystalline, and 

 more compact and porphyritic looking. How far, however, this dif- 

 ference may be due to the difference of the conditions under which 

 they were produced, or how far it might bear us out (in the absence 

 of contrary evidence) in supposing them to be only connected at a 

 considerable depth, I am not prepared to say. There is certainly no 

 reason to suppose them to have been produced at different periods of 

 time. 



These are the principal materials of which (so far as has yet been 

 ascertained) the county of Leicester is composed, and the positions 

 which they occupy with respect to each other. It remains for us 



