280 



Memoir on ike Geology of the 



Oct.] 



several excursions in the neighbourhood, I shall describe their geolo- 

 gical features first, and say a few words afterwards on scenery and other 

 subjects. 



Going up from Sispara (where the Pioneer's Camp is) three miles 

 along the new road, we come to a deep ravine along which the road 

 passes, and the western end of the same where we found the charac- 

 teristic pegmatite. Before reaching this we see in the bed of the 

 torrent the implanted pegmatitic masses traversed by trap (No. 143) ; 

 and half way up the left hill there are some protruding masses of gra- 

 nite (No. 144). Ascending still the rise of this hill, to the little 

 flat at its foot, nearly all the protruding masses are granite (No. 145), 

 the mica predominating ; and it appears that these blocks must have 

 been hurled down from the hill just in front; since, although loose 

 boulders, many of them are traversed by basaltic dykes. At the foot of 

 the hill, these blocks, either loose or implanted, exhibited few or more 

 of these dykes. The extensive convex acclivity of this side of the hill 

 (S. W.) is formed by an immense mass of basalt which lays mantle- 

 shaped on its side and, spreading over its summit, caps it also ; and, 

 in both places, it entangles stones of granite of different dimensions 

 and shapes. 



But the eastern side of this same hill has a different formation. Al- 

 though the colour, aspect, configuration, &c. of the rock appear simi- 

 lar on both sides, yet there the rock is all granite, of the three usual 

 minerals, the surface of which only differs from the basaltic side in 

 being rough with little prominences and cavities (No. 146). There is 

 an enormous mass of this rock projecting from the sides of the hill, 

 which is cut in an horizontal direction by a basaltic dyke more than a 

 foot thick, and the line of demarcation, between the intruded and the in- 

 truding rock, is well and clearly defined (No. 147). Probably the sur- 

 faces of both rocks were at one time in the same line, but the upper 

 part of the granitic mass, which overlays the dyke, having exfoliated 

 to some depth, the upper surface of the dyke forms a kind of little shelf. 



If, instead of returning to Sispara by the new road, we follow the 

 verge of this group, which terminates at Sispara, we meet with no 

 other rock but granite, the w 7 hole way. Sispara, or Murraypet, is at 

 the head of the long and deep ravine, enclosed between two almost 

 perpendicular ridges; along the side of one of which (N. W.) the 

 Ghaut is to be constructed. Lieut. Johnson of the Engineers, makes 

 the absolute height of Sispara about 5,623 feet. 



Passing through the huts of the encampment, and ascending the bluff 

 high peak of Sispara, half an hour's walk leads to a mural precipice 

 (the escarpment facing the plains of Malabar), the height of which 

 cannot be seen, on account of the numerous trees growing at the foot of 

 the precipice, but it cannot be much, since the tops of these lofty trees 



