96 FOOTE : GEOLOGY OF MADURA AND TINNEVELLY DISTRICTS. 



increases, the whole waste will eventually be reclaimed, for the teris 

 are by no means barren sand heaps. Mixed with the silicious 

 grains is very frequently a percentag-e of fine red clayey matter large 

 enough to make in the presence of sufficient water a very fairly produc- 

 tive soil. 



The rate of advance of the sands on the Ittamoli (Sathaukulam) teri 



Rate of advance of ^^^ been conputed by Lieutenant-Colonel Branfill, 

 *^6"s. Deputy Superintendent, Great Trigonometrical 



Survey, to have been 1,000 yards, or nearly 17 yards a year during 

 the 60 years which elapsed since Colouel Lambton (in 1808-9} fixed his 

 Trigotiometrical Station (Red Hill Station of Atlas sheet) on the top of 

 the teri. In the four years, however, from 1869 to 1874, the advance 

 was only at the rate of 6 yards a year. In both series the direction of 

 the advance was the same, namely, towards the east-south-east. 



The greatest developments of the coast dune sands in Tinnevelly 



Coast dunes at Mana- ^^^s been along the coast from a village called 

 P^*^- Talai to Manapad point. Here the sands, which 



form a high ridge and are extremely calcareous from the great quimtity 

 of comminuted shells they contain, have been to a great extent solidified 

 in some places perfectly, and others imperfectly. In many places 

 the action of the high westerly winds has carried away the loose sand 

 from the consolidated part and left the latter 



Cousolidatiou of sands. 



standmg up in strangely shaped masses. This 

 process of consolidation has gone on much more strongly near the eastern 

 end of the ridge probably because exposed to heavy spray drifts during 

 storms in both monsoons. The rock formed here, which often contains 

 marine shells as well as specimens of Helix rittata, is hard enough to 

 be used for building purposes. 



The Manapad sand ridge must be fully 100 feet high or more. 

 The sands on the north side of the ridge are quite unconsolidated, 

 and in the village of Manapadu (Manah paud) they have been heaped 

 up amongst the houses and churciies in such a way as to render some 

 of them almost untenantable. Some small buildings are said to be quite 

 ( 96 ) 



