SOILS. 85 



cut throuo-li in making an excavation for some railway work.^ The 

 averao-e thickness is far smaller, and may probably be set down at about 

 4 feet or rather less. The base of theregur bed is here as in other places 

 often hio-hly calcareous from the presence of a large accumulation of 

 small gravelly kankar. 



No organism of any kind was seen in tbe 

 No fossils in the regur. o n/r i i m- n i- i • a 



regur or Madura and inmevelly districts. 



The red soils being generally tbe product of decomposition in situ 



of underlying ferruginous rocks, vary considerably 

 Varieties of red soil. . ■,■,■, t t J^ p 



in character. Over hornblendie and other rer- 



ruginous forms of gneiss they are very ferruginous. Near the great 

 and conspicuous beds of granular quartz rock the soil is very gritty 

 and of pale red colour. The soil derived from the decomposition of the 

 highly silicious variety of gneiss, such as that which I have called the Cape 

 Comorin type, is very sandy and of pale reddish colour. A very remark- 

 able formation of deep red loamy soil occurs in a band several miles 

 Eed loam along the i^ width along the foot of the Southern Gh^ts, 

 base of the Ghats. especially in the bay-like recess formed by the 



great curve of the mountain-range to the north and west of Kuttalam 

 (Courtallum). This is very probably a pluvial deposit brought direct 

 down from the mountain flanks, but it has not been sufficiently examined 

 (because mostly out of the limits of the area surveyed up to the 

 present) to have enabled me to form any positive opinion as to its origin. 

 A very remarkable feature connected with the red loamy soil, which 

 covers so much of the surface in the south-western 

 part of Tinnevelly District, is the enormous number 

 of white-ants' (Termites) nests. They are often so numerous as to 

 affect very strikingly the character of the fore-ground of the landscape 

 as their generally large size and bright red colour make them very 

 conspicuous objects. They attain a height very generally of from 



^ I am indebted for this fact to Mr. Spalding, C.E., of the South Indian Railway, who 

 further had the kindness to lay down the course of the railway on my maps with far 

 greater correctness than it is given in the last edition of the Altas sheets. 



( 85 ) 



