GEOLOGY. 291 



Cambrian, like the Montalban series of North America, which 

 it closely resembles. Areas of similar rocks are found near 

 Loch Maree, in Scotland. 



LEICESTERSHIRE. 



The crystalline rocks of Charnwood Forest, in Leicester- 

 shire, which rise like islands through the Triassic strata, have 

 been examined by Hill and Bonney. They consist in part 

 of ancient eruptive rocks, including probably the reddish 

 hornblendic granitoid masses of Mount Sorrel, and in part 

 of crystalline schists which, like those of the Welsh areas, to 

 which they are compared by Hicks, will probably be found 

 to contain representatives of two or more pre-Cambrian se- 

 ries. Portions of them, according to Hunt, closely resemble 

 the Huronian of North America. 



SHROPSHIRE. 



Another area of crystalline rocks appears in Shropshire, 

 forming several hills, among which are the Wrekin and Caer- 

 Caradoc. The former of these was described by Murchison 

 as an igneous outburst which had altered to a quartzite the ad- 

 jacent sandstones, then believed by him to be of Caradoc age 

 (Upper Cambrian, Sedgw.). Callaw r ay has, however, shown 

 that the crystalline rocks are unconformably overlaid by the 

 fossiliferous strata, which are in part of Tremadoc age, and 

 in part identical with the Hollybush sandstones of the simi- 

 lar Malvern area, which are probably Menevian. The quart- 

 zites in question are still older, and, in the opinion of Cal- 

 laway, are perhaps pre-Cambrian. They contain worm-bur- 

 rows, but no other evidence of organic life, and rest uncon- 

 formably upon the still older, or so-called, volcanic series. 

 The greenstones, which form a part of the latter, are, accord- 

 ing to Allport and Callaway, distinctly bedded. Another 

 portion consists of rocks which, according to Hunt, are red- 

 dish banded petrosilex- porphyries, sometimes epidotic, and 

 resemble closely the Arvonian series of Wales and the simi- 

 lar rocks in North America. 



ARDEXXES. 



Portions of the ancient crystalline rocks of Charnwood 

 have been by Hill and Bonney compared with those of the 



