Chap. VI.] superficial deposits and soils. 135 



the inland shores of this lagoon, which is sometimes, if not always, filled 

 with fresh water, that regur-like soil is now forming*.* 



It is evident from the above that shells might be expected to be 

 found in undoubted black lagoon mud in some cases, though rare in the 

 Cliilka and Negombo lakes, cited by Mr. Blanford. 



Another argument in favor of the fresh water character of the reo-ur- 

 High level spread of depositing waters may be drawn, and apparently 

 regur. ^^-^j^ ^^^^ reason, from a consideration of the 



various levels at which the Cotton-soil occurs. It has already been ob- 

 served (see page 132) that spreads of regur occur at comparatively great 

 elevations above the level of the Indian Ocean ; as, for example, at 

 Adamancotta, Darmahpoor, and other places in the Baramahal, and to 

 the west of Namcul, in the low country. 



In the first cases, if the plains around Darmahpoor and Adamancotta 

 had become covered with regur, through the existence of brackish water 



* Since our examination of the Cotton soil of the south, I have seen the greater part 

 of the Nellore coast, in which is included nearly the whole of the Pulicat lake, and though 

 there is evidence of a very considerable area of back-water alluvium, which is now dry and 

 cultivated land, I have seen no true Cotton-soil, though there is an approach to it, while 

 the back-water alluvium differs from that of the rivers (which is generally a pale sandy de« 

 posit) in being dark coloured and humic. The only approach to a black soil like Cotton 

 soil appeared to me to be forming in two long parallel fresh water jheels between the Soor- 

 namookey and Kistnapatam, and similar swamps thickly covered with screwpine (Pandanus) 

 and Rattan jungle on the long sandy spit which forms the eastern shore of the Pulicat lake. 

 The dried up parts of this lake show a dark grey calcareous mud, with remains of estuarine 

 shells.— W. K. 



The dark coloured clayey or sandy and clayey mud turned up In various parts of the 

 Covelong back-water (in digging wells whence the brine is during the cby season pumped 

 into the salt pans) abounds generally in sub-fossil shells of existing marine and estuarine 

 mollucca. This dark clay and the shells are met with at frequent intervals between Cove- 

 long and Madras, as shown by the soil turned out m digging the canal to Sadras, Both the 

 clay and the shells are also to be met with under various parts of Madras in sinking for 

 water, which is almost invariably of bad quality when it has to traverse the black clay.— 

 R. B. F. 



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