62 



GRANITE MOUNTAINS. 



summits are uncovered by snow, they are believed to be composed 

 of secondary strata. 



Many of the mountains in the extensive range of the Andes if 

 South America, also rise much higher than Mont Blanc; but, gran- 

 ite has not been found there in a greater elevation than eleven thou- 

 sand five hundred feet, an elevation exceeded by many of the gran- 

 ite mountains in Europe. The range of the Andes is the seat of active 

 volcanic fires, which appear to have covered the primary mountains 

 with an immense mass of matter, ejected by ancient and recent erup- 

 tions. In Mexico and New Spain also, the granite appears to be 

 nearly covered by basalt, porphyry and lava, ejected from the nume- 

 rous volcanoes which now exist, or have existed in those countries. 



To this accumulation of volcanic matter, the mountains in South 

 America, owe their superior elevation. Chimborasso and Cayambo, 

 are nearly the highest mountains in the Andes, — the former rises 

 twenty one thousand four hundred and forty feet, — but their summits 

 are vast cones, composed of volcanic productions covered with snow. 

 Chimborasso is one mile and one hundred and sixty yards higher 

 than Mont Blanc. The general arrangement of the Andes consists 

 according to Humboldt, of granite, gneiss, mica and clay slate, as in 

 the Alps ; but, on these, are frequently laid porphyry, and basalt, 

 " arranged in the form of regular and immense columns, which strike 

 the eye of the traveller like the ruins of enormous castles lifted into 

 the sky." 



In the eastern parts of the United States, and in Canada, granite 

 is seen, near the surface, uncovered by other rocks, and does not 

 rise to any great elevation. The constant occurrence of granite, at 

 a lower level in America than in Europe, is a remarkable geological 

 fact. In Europe, the central part of the principal mountain ranges 

 are granite; as in Scandavia, the Alps, the Pyrenees, and the Car- 

 pathian mountains. In Asia, granite forms a considerable part of the 

 Uralian and Altaic range of mountains, and it appears to compose 

 the principal mountains that have been examined in Africa. 



The parts of England and Wales where granite and granitic rocks 

 occur, are Cornwall, Devonshire, North Wales, Anglesea, the Mal- 

 vern Hills in Worcestershire, Charnwood Forest in Leicestershire, 

 and in Cum^berland and Westmoreland. Granite rises near the bot- 

 tom of Skiddaw in Cumberland. The granite near Shap in West- 

 moreland is porphyritic, containing large crystals of red felspar. 

 There are rolled masses of granite on the banks of Ulswater, resem- 

 bling the granite of some parts of Cornwall and of the Wicklow 

 Mountains in Ireland, but more highly crystalline than the latter. 

 The felspar is in large white and reddish-white crystals. The mica 

 is a blackish green, and on the outer parts, decomposed. I am in- 

 clined to believe, that the same formation of granite, which just 

 makes its appearance on the western side of England and Wales, is 

 continued under the Irish Channel ; or, if broken there that it rises 



