50 KING : NELLORE PORTION OF THE CAKNATIC. 



lying clay-slates ; and their altered condition is plainly attributable to 

 the great crushing and folding displayed in nearly every cross gully or 

 gorge in the mountain wall. 



Throughout this description of the metamorphic and sub-metamor- 

 C. M. Oldham's notes phic rocks, I have availed myself largely of the 



PennIr!" 0CkSn0rth0fthe notes and fiel d ma P s o£ the la * e Cnarles Oldham, 

 referring to the southern half of the field ; but as 



I myself only touched very slightly on the country north of the Penner, 



I think it best to give his remarks on that area in exlenso : — 



" The rocks to be noticed are throughout of the metamorphic class, 



with exceptions to be noticed hereafter, and may be generally described 

 as alternating bands of hornblende schists, micaceous talcose schists, 

 gneiss (proper), and quartz-rocks — an intensely quartzose gneiss. This 

 quartz -rock forms a very marked feature of the country — many, indeed 

 the great majority of the small ridges and hills, consisting largely or 

 exclusively of it — owing, doubtless, to its great hardness and consequent 

 power of resisting denudation and atmospheric action. 



" There are, however, as noticed hereafter, some instances near the 

 ghats of a quartz-rock of another series, overlying and uneonformably 

 overlying these older metamorphic rocks. 



" In going across the country westward from the coast to the lino 

 of the ghats, we first rise from the alluvial deposits and sands over a 

 scarped ridge of laterite nearly continuous from the river to the north of 

 the sheet, and descending on the west, frequently over well-marked scarps 

 and bluffs of 20 to 40 feet, find ourselves in the region of metamorphic 

 rocks, which extend thence in uninterrupted succession to the ghats in 

 a series of rolling beds. 



" Locally granite and quartz veins are numerous, but small. There 

 is considerable variety in these metamorphic rocks. Typical gneiss, of 

 compact substance, is comparatively poorly represented, though it occurs 

 in several places, and is in some of these largely quarried for building 

 purposes, as, for instance, near Boochareddypalliam (a large village about 

 12 miles north-west of Nellore), where on the north of the village a 

 close-grained compact granitoid gneiss occurs in considerable quantities, 

 ( 158 ) 



