143 



Description of the Valley of Sondur. 



[July 



as they ascend. Towards the summit is a convexity in the face of the 

 precipice on the right, and an almost corresponding depression in that 

 of the precipice on the left, hand : a large fissure cleaves the substance 

 of both rocks in a direction S. 20 E. 



The bed of the stream as in the eastern pass is choked up by blocks, 

 pebbles, silt and sand. These cannot have been transported any dis- 

 tance, as they are of the same nature as the surrounding formation, and 

 the edges of the harder fragments but little worn. The mineral cha? 

 Tacter of the rock here is similar to that of the eastern pass. 



Direction of laminae S. 20° E. 



Dip of do. at 65 east. 



Direction of joints S. 



Dip of do. at 10°- east. 

 Tt seems plausible, from a careful examination of the summit, sides, 

 and bases of the rocks, the bed of the stream, and the face of the sur- 

 rounding country, that the singular breaks through the line of ele- 

 vation of these schistous ranges owe their present appearance to 

 two modes of action, viz. separation of the rock in the first in- 

 stance, and in the next to watery abrasion. It would be ditficult to 

 determine whether the former was first occasioned by volcanic convul- 

 sion, or contraction of the substance of the rock after deposit, as seen 

 in sand stone formations. The marks of watery erosion of the stream, 

 probably under a different former state of dynamical action, are tracea- 

 ble as high as 40 feet above the present bed of the stream, in the 

 rounded pebble gravel formed upon a ledge of the rock, in the softer 

 parts of the rock being worn away leaving the harder mass protrud- 

 ing like an abutment towards the stream, and from the comparatively 

 greater number of cavities in the western face of the rock, once the re- 

 ceptacles of felspar or vesicular hematite, and now washed out by the 

 stream which runs from the east. From what I could gather from the 

 natives, the action of any present flood is insufficient to account for 

 the presence of gravel at the height of 40 feet on the sides of the 

 rivulet. 



The precipitous disrupted appearance of the rocks at a distance from 

 the sides of the ravine, far removed from the infi^uence of the stream, 

 and the corresponding faces of the rocks in the western pass, ihe ab- 

 sence of any continuous beds of rock connecting the bases of the oppo- 

 site precipices, indicate the fissure not to have originated from watery 

 erosion. 



