Chap. VI.] suPEiiFrciAL deposits and soils. 125 



been woi'n in the deposit by the streams. In one very good example, 

 north of Toriore, a perpendicular- sided gully below Goondoor Peak, the 

 bottom of the soil is not seen even at a depth of 15 feet. 



At various depths there are layers of rolled and sub-angular frag- 

 ments of gneiss and quartz, the size and quantity of the boulders de- 

 creasing- in proportion to the distance from the base of the mountain. 

 In the bed of a stream which flows west from a narrow neck on the 

 Patchamullay plateau, past Woodianputty, to the Permalpolliam 

 tank, some very characteristic deposits of boulders and gravel are 

 to be seen. A vegetation similar to that of the grits, such as Tamarind, 

 INIango trees, and Euphorbias, with other thorny plants, characterises this 

 belt ; at the time of our survey, the castor-oil appeared to be the plant 

 principally cultivated on it. 



The Ldl is in many cases nothing more than the result of the 

 decomposition of the underlying or closely adjoining rocks of the meta- 

 morphic series, which are all more or less ferruginous, and have a more 

 irregular texture than the grits. 



The red and sandy soils are very largely cultivated for, and appear to 

 • Fertmty of coarse ^^ admirably adapted to the gro^vth of, dry grain 

 arenaceous soils. crops ; the survey of the country south-west of 



Trichinopoly was being conducted in the months of September and 

 October, and at that time most luxuriant crops of cJiohim, cumboo, and 

 ragee were ripening on all sides. Many of the cholum crops were 8 

 or 10 feet in height, while the ears of grain were correspondingly large. 

 In the month of July fine crops of the Gingelly oil plant (Sesamum Incli- 

 cum) were noticed growing on the red sandy soil of the Cuddalore sand- 

 stone plateau. The same plant appears to thrive also on an identical 

 soil in the neighbourhood of Trivellore, 25 — 30 miles westward of Madras. 

 This part of the country is also much better wooded than any other part 

 of the country which is not actually covered by forests, excepting only 

 the eastern edge of the delta. A view from any of the elevated ridges 



( '3i7 ) 



