Mr Calder on the Geology ofliulia. 153 



oF the elevated portion of thai chain ; gneiss being, according to 

 Captain Herbert, the predominating rock, along with granite, 

 mica^'schist, hornblende, chlorite-schist, and crystalline limestone. 

 On these repose clay-slate and flinty-slate ; and, towards the 

 base, we find sandstone composing the southern steps of the 

 chain, and forming the north-east barrier of the valley of the 

 Jumna and Ganges, by which, and the diluvial plains of Up- 

 per Hindoostan, this great zone is separated from the mountain 

 ranges of the peninsula. The opposite or southern boundary 

 of this valley is of the same rock. Advancing to the south, 

 we come to three inferior mountain ranges on which the penin- 

 sular table-land of India may be said to rest, or, more properly, 

 to which it owes its peculiar form and outline. We may con- 

 sider these ranges separately: the western, or Malabar; the 

 eastern, or Coromandel ; and the central, or Vindya. Of these, 

 the principal in elevation, and most remarkable in continuity of 

 extent, is the western, which may be said to commence in Can- 

 deish, and runs along the Malabar coast, within a short distance 

 of the sea, in an unbroken chain, to Cape Comorin, excepting 

 where it is interrupted, near its southern extremity, by the great 

 chasm which forms the valley of Comibitoor. The direction of 

 this chain deviates but little from north and south, bending a 

 little eastward towards its southern extremity. Its elevation 

 increases as it advances southward ; the highest points being 

 probably between latitudes 1 0° and 15°, where the peaks of gra- 

 nite rise to 6,000 feet and upwards. 



The northern extremity of this range is entirely covered by 

 part of the extensive overlying trap formation, to be more parti- 

 cularly described hereafter ; extending, in this quarter, from the 

 sea-shore of the northern Concan, to a considerable distance 

 eastward, above and beyond the Ghauts, as far east and south 

 as the river Tumboodra and Nagpore. These rocks assume all 

 the various forms of basaltic trap, passing from the columnar 

 (of which some fine specimens are to be seen opposite to Bas- 

 sein, near Bombay,) into the globular, tabular, porphyritic and 

 amygdaloidal ; the two latter containing an unusual abundance 

 and interesting variety of included minerals peculiar to such 

 rocks. The landscape liere exhibits all the characteristic fea- 

 tures of basaltic countries ; the hills rising abrupdy in perpen- 



