®§ A r o(es f chiefly Geological, of a Journey [Jan, 



almost exclusively; those to the south are, in general, gneiss with 

 garnets, with one or two hills of granite. The porphyritic for- 

 mation seems to extend as far as the Ma ( handry mountain (N.), the 

 highest in this district, which does not appear to have the con- 

 formation, outline, and black aspect, of those formed of por^ 

 phyry. The soil all along the level of the pass, is sand and clay of 

 a reddish colour ; the nodular kankar forms the stratum under the vege- 

 table soil, and is also scattered on its surface. A few pieces of loose 

 lateritic stone were met with, but none implanted in the ground ; the 

 gravelly detritus of this ferruginous claystone on the soil was not 

 scarce. 



Poondy, March 5. — The sand, over the whole plain before reaching 

 this place, is very fine grained, whitish and extremely loose. Having 

 ferried over the river near Poondy, we proceeded to our camp, pitched 

 on a sandy eminence, not two hundred yards from the sea. In the 

 swamp, between the river and Poondy, are numerous blocks produced 

 hy the oysters, which are very abundant at this place, the masses pro- 

 jecting some feet above the mud. They are composed of nothing else 

 but oyster shells, with little cement agglutinating them. These are the 

 only rocks at Poondy ; cut into square pieces they are used for con- 

 structing the walls of huts ; with them, also, they line the interior of 

 wells, to prevent the sand, through which they are dug, from falling 

 in. The water of these wells, although a few yards only from the sea* 

 is perfectly fresh and drinkable. 



About two miles north of our camp, near the beach, a village is situ- 

 ated at the foot of a granitic hill, the rock of which is composed of a 

 great quantity of garnets and hornblende, with felspar. At the surface 

 of some blocks the rock appears stratified, but the huge masses at the 

 summit are all unstratified. In the more compact pieces the felspar 

 changes into albite (No. 56) ; and some, composed of a prodigious num- 

 ber of large amorphous garnets, are knobby on the surface, owing to 

 the two other minerals having decomposed, and left the decomposing 

 garnets, like small filberts, protruding (No. 57). Not rarely some 

 masses are entirely formed of garnets, to the exclusion of the other 

 minerals. All the black looking masses along the beach and protrud- 

 ing from the sea, opposite to this hillock, are the continuation of this 

 rock. 



Poondy, March 9. — The whole plain west of this place, and along 

 the shore for some miles, is covered with a very thick deposit of 

 whitish, extremely fine, loose sand, which, extending for a quarter of a 

 mile inland, is undulated with numerous swells and small elevations 

 of this highly comminuted sand, on which nothing but a species of 



