90 FOOTE : GEOLOGY 01? MADURA AND TINNEVELLY DISTRICTS. 



stand perched on great cones of fibrous roots 6 to 10 feet high, as 

 shown in the diagram sketch. 



In several places where the teri has been deeply cut into by wind 

 action, banks of dull Indian-red loam are seen to be exposed, which show 

 distinctly their true seolian origin by the peculiar false bedding, often at 

 very high angles, observable among blown sands. This teri, like most 

 of those in South Travancore which I described in my paper on the 

 geology of South Travancore,^ is in a state of degradation ; only a thin 

 sprinkling of sand on the surface of the teri is now affected by the wind. 

 The main mass has been partially solidified or fixed by the action of rain 

 water percolating from the top aided by the action of heavy showers, 

 which have fallen on the surface and washed the lighter clayey and 

 smaller, though heavier, ferruginous particles down the slopes or into 

 hollows where on drying a fairly hard, often slightly glazed surface of 

 dark red loam has been found. This loam is very fairly fertile, and 

 soon becomes covered with vegetation, which further helps to defend 

 the surface against wind action. The loose sand when deprived of the 

 clayey and finer ferruginous particles, unless unusually coarse in grain, is 

 carried off by extra high winds, or remains on the surface in shallow 

 barren wreaths of lighter red colour. This Kuttan Kuli teri shows more 

 of the fixed loam formation than any of the other teris eastward of Cape 

 Comorin, and less of the rich loamy form of the loose sand. 



The teri north of Kuttan Kuli saltpan creek offer no special features 

 worth noting. It runs up to the estuary of the Nambi-ar, and has great- 

 ly covered up the shelly grit beds occurring there. 



Immediately on the east side of the Nambi-ar estuary begins the 

 great Iddayangudi teri which extends north- 

 eastward for fully 15 miles, and increases till 

 it reaches the south end of the Taruvai lake. At its western ex- 

 tremity it is a mere narrow strip, but increases in width after a couple 

 of miles, and then runs on with an average width of about 2 miles till it 



^ On the Geology of South Travancore, by R. Bruce Foote, Deputy Superintendent, 

 Geological Survey of India. Kecords, G. S. I., Vol. XVI, pt. 1, 1883, page 32. 



( 90 ) 



