Chap. III.] post-cretaceous rocks. — (cuddalore sandstones) . 43 



flat shallow valley filled with white soil, abounding in quicksands along* 

 the banks of two or three large nullahs which run north. This white 

 soda-soil lies on the gneiss, which, however, is only occasionally exposed, 

 as, by the side of the road a few hundred yards west 'of Buttalur 

 (Buddelur) Trig, station, to which place the boundary of the Cuddaloi'e 

 sands trends generally north-east from the spot where it crosses the 

 Trichinopoly road. This white soil is not only very barren, producing 

 little more than low prickly gum-tree {Babul) jungles, but, owing to the 

 large quantity of soda and potash it contains, is veiy unstable, causing 

 very serious trouble in maintaining the earth-works in connexion with 

 the high road and the Great Southern India Railwa}^ (between Trichi- 

 nopoly and Negapatam) . 



On the left or west side of the valley above referred to, about half 

 a mile east of the Travellers^ Bungalow at Thoongoody, the laterite again 

 appears, in all probability a continuation of the Singiputty deposit. It 

 here makes a considerable spread in all directions, but chiefly to the 

 south, where it extends beyond the limits of the map. It forms a bay 

 round the MummuUay (a group of low rounded gneiss bosses) , and spreads 

 northwards almost down to the alluvium, from which it is divided by a 

 narrow strip of gneiss. The higher grounds are regularly capped by it, 

 and numerous small springs issue from below the scarped edges, which 

 form a contour line along the slopes. It confines itself almost entirely 

 to the higher ground, being scarcely ever found in the depressions 

 occupied by existing streams. 



Crossing the great bay of alluvium which runs south for some 

 miles from the Errumbesprum Pagoda Rock, there is another laro-e 

 patch of laterite-conglomerate, which commences about a quarter of 

 a mile north of the new Trichinopoly Road, crosses the old road a 

 little south-east of Ponmullay (Golden Rock), and making a bend 

 like the lower limb of an S, terminates a few hundred yards west 

 of the village of Sunthasaputty, and about Ij mile south of ^^Fakir^s 



( ;iG5 ) 



