342 Reviews. [April, 



The country treated of consists for the most part of highly-in- 

 clined metamorphic rocks, principally gneiss, with bands of crystalline 

 limestone, trap dykes, and magnetic iron. The Geological age of 

 these rocks is altogether uncertain, and they are succeeded by the 

 Cretaceous and Post-Cretaceous formations of the Payen Ghat, or low 

 country of the Carnatic. These latter form extensive plains or 

 terraces, stretching from the interior to the coast in some places, 

 while in others they are overlaid by very recent deposits of fluviatile, 

 or marine origin, in which shells identical with those now inhabiting 

 the neighbouring sea have been found. The alluvial deposits of the 

 deltas of the Cauvery, Punniar, and Guddeiom rivers are very ex- 

 tensive, and owing to their liability to floods from the rivers them- 

 selves are rescued from the curse of barrenness which overhangs the 

 sandy plains by which they are bounded. In the interior, the 

 crystalline and metamorphic rocks rise into several lofty ranges, be- 

 longing to the Eastern Ghats, of which the most distinguished are 

 the Shevaroys, which, in the Green Hill Ridge, reach an elevation of 

 5,2G0 feet. This mountain is deeply indented by ravines, especially 

 that of the Vaniaur river, a tributary of the Punniar. Along the 

 sides of this ravine nearly perpendicular walls of bare rock rise to a 

 height of a thousand feet, and the authors speak with rapture of the 

 grandeur of the views along the road from Yercaud to Shenguttapady 

 from the brow of these splendid precipices. 



Space forbids a further reference to the general Geology of this in- 

 teresting region, though there are several points upon which we should 

 gladly linger. We therefore hasten on to notice that special feature 

 which renders the Salem district almost unique in a mineral point of 

 view. We refer to the wonderful hills of magnetic iron ore, which 

 have rendered this district famous from very ancient times. These 

 iron-beds occur in many places throughout the country of Salem and 

 South Arcot. They are interstratified with the gneissic, or meta- 

 morphic rocks, following their foldings, or running for miles along 

 the ridges of the hills with marvellous persistency. In the district 

 under consideration there are four distinct groups of these iron-beds, 

 some of which, as that of the Godumullay hills, form the serrated 

 crests of the ridges, rising upwards of 1,200 feet above the valleys. 

 On the northern side of this ridge, the iron-rock suddenly terminates 

 in a splendid precipice several hundred feet high, overhanging in 

 some places. These massive cliffs form the subject of the frontis- 

 piece to the memoir. 



The most remarkable of these masses of magnetite lies just beyond 

 the western limits of the district, and is therefore described in the 

 appendix — it is the ridge of Kunjamullay. 



The ridge attains an elevation of 2,000 feet above the sea, and of 

 1,000 above the surrounding plain. It is of an elongated form, four 

 miles in length ; and around its flanks, several beds of magnetic iron 

 crop out in a series of oval rings, imbedded in garnetiferous gneiss 

 and other schistose rocks, and dipping at every point towards the 

 centre or axis of the ridge. From this description it will be apparent 

 that the ridge is coincident with the axis of a synclinal fold, and that 



