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Geology of the Deccan. 



[Oct. 



magnesian below the red sand, where the rock salt and gypsum, 

 and where, above all, the characteristic organic remains of the 

 lias and magnesian limestone ? It would be idle, therefore, to spe- 

 culate on the era of a formation without a standard of compari- 

 son to direct the judgment. The question of the manner of the 

 formation of the horizontal beds of trap with their vertical edges 

 is very interesting. It will be said they were ejected under the pres- 

 sure of an incumbent ocean. If such had been the case, where are the 

 marine remains, and would not there have been sedimentary deposits 

 upon them ? Moreover, if viewed as coulees from craters, would not the 

 beds have thinned out, instead of preserving the parallelism of their sin 

 perior and inferior planes and their vertical edges. 



Lalerite.* — Laterite is a ferruginous clay mottled red and yellowish, 

 "When first dug from its bed, it is soft, and is easily fashioned into the 

 form of bricks or large square masses for building; and if my re- 

 collection serves me right, it constitutes the material of the walls of 

 the fort at Tellicherry and the jail at Calicut. It rapidly indurates 

 on exposure to the atmosphere. It is destitute of fossils as far as is 

 yet known. 



That curious and very extensive rock, aptly denominated laterite 

 (I learn from the information of a friend), occurs at the source of 

 the Kristna river in latitude 17° 59', at an elevation of 4,500 feet 

 above the sea. It covers the low land between the sea and the great 

 western range from the southern Konkun to Cape Comorin,and, agree- 

 ably to Dr. Davy, passes into Ceylon. I casually observed it at Tel- 

 licherry and Calicut, respectively seven hundred and forty-four and 

 seven hundred and fifty-six miles south of Bombay ; and at Calicut 

 granite rises through it. On the low land at the base of the great 

 eastern range, Mr. Calder says it re-appears between the 11° and 12° 

 parallels of latitude, and recurs in increasing patches passing north- 

 wards, covering granite. The Rev. Mr. Everest speaks of laterite 

 forming a fringe to great part of the bay of Bengal and covering the 

 edge of the granite of either peninsula. f 



Nodular Limestone.~\n addition to the evidence already adduced of 

 the extensive occurrence of nodular limestone, Dr. Buchanan mentions 



* With regard to laterite, see note at foot of page 364 of this article, and the former 

 Number* of this Journal quoted therein. — Editor Madras Journal. 



■t Gleanings of Science, vol. iii, p. 135, 



