1845.] across the Peninsula of Southern India. 403 



till at length the base of the Ghauts is reached near Udigherry. The 

 hypogene schists, penetrated by granite and dykes of basaltic green- 

 stone and overlaid by patches of kunker, continue up to the base of 

 the Ghauts. Mica schist is seen at Samulraygudda, about four and a 

 half miles E. S. E. from the town of Udigherry, and also about seven 

 miles farther to the S. W. at Timmapolliam with quartz rock. Se- 

 veral of the hypogene spurs in the plain are capped with, this quartz 

 rock, which is usually of a light reddish eolour passing into greenish 

 grey, and white cherts. It is evidently altered sandstone. The hy- 

 pogene schists are in great confusion at the base of the Ghauts, and in 

 one place I observed the mica schist dipping at an angle of 41° to the 

 W. i. e. towards the great line of dislocation. In some places they are 

 but little inclined ; in some vertical ; while in others they appear to 

 have been reversed, and folded back upon themselves, the upper parts 

 of the flexures having disappeared in weathering or by denudation. 

 Hence they have the appearance of alternating in a reversed order to 

 that in which they usually occur, viz., the gneiss lowermost in the se- 

 ries. This occurs in most other hypogene areas of South India, and 

 care should be taken to ascertain in such disturbed regions the true 

 order of superposition from the horizontal or less inclined beds in the 

 neighbouring districts less disturbed, and where there is no likelihood 

 of inversion or folding back of the strata. These phenomena, though 

 written in plainly legible characters on the faces of the gigantic es- 

 carpments of the Alps, must in Southern India generally be patiently 

 traced out, letter by letter, amid the jungle and debris which usu- 

 ally obscure their features. 



Eastern Ghauts. The Eastern Ghauts, in the vicinity of Udigher- 

 ry, and the Dorenal Pass, have an altitude, approximatively obtained 

 by a rough trigonometrical measurement, of about 700 feet from the 

 maritime plain at their base, which is from 60 to 70 miles broad, its 

 surface roughened by spurs from the Ghauts, and a few occasional 

 rocky clusters and detached hills. 



The Ghauts here have usually their escarpments, or steepest acclivi- 

 ties facing towards the East. The lower portions of the hills, which 

 are composed of mica slate or gneiss, have usually a much less abrupt 

 and steep descent than the sandstone, which often caps them in mural 

 cliffs and hog. backed ridges. The line of junction of the two rocks 



