SKETCH OF THE 



argillaceous sclnsts, and the more durable varieties of argillaceous schist, 

 while peaks, often of fantastic form, are seen rising above the surround- 

 ing hills. The softer argillaceous schists occur generally forming round 

 backed hills and gentle swells. While the granites, hornblende rocks, 

 which approach to primitive greenstones, &c. are frequently arranged in 

 large globular heaps piled on each other, as if artificially. The pure 

 white quartz rock, too, frequently assumes the form of low rounded 

 swells, entirely destitute of soil, and resembles, in the distance, extended 

 plains covered with snow. 



The form of the hills in this district is constantly liable to change — 

 during the rains immense blocks of the harder rocks are detached, and 

 the process of decomposition in the softer and less durable varities is car- 

 ried on with amazing rapidity. Hence its rugged and broken aspect, and 

 this ruggedness is yearly increased by the channels which the hill tor- 

 rents are constantly forming for themselves. 



That this district has been subjected, at various periods of time, to 

 those violent convulsions of nature which have operated with greater or 

 less force in every quarter of the globe, there can be no doubt. The deep 

 valleys and rugged ravines — the sliding o& or sinking of the strata form- 

 ing the whole sides of mountains, a narrow ravine only separating the de- 

 tached portions from the parent hills, — ^all which appearances are frequent- 

 ly observed in this portion of the country, are sufficient to prove this ; but 

 let not a love for the marvellous lead us beyond the limits which reason 

 has prescribed. The difference observed in the nature and durability of 

 the rocks, and their capability or the reverse of resisting the decomposing 

 effects of the atmosphere, of the mechanical effects of water, &c. will ac- 

 count for very many of the appearances described, and in a climate like 

 this these causes operate with amazing force. 



