og GEOLOGY 07 TRICHINOPOLY, &C. [ChaP. III. 



Again^ at Tanjore^ above the fort^ and in the ditch of the little fort or 



citadel, there is a fine display of mottled grits, which 



and Tanjore. 



are covered up by pale drab or reddish sands pass- 

 ing to the south-east and east, and the grits are but rarely seen. 



On the top of the rising ground immediately east of Vellum stand 

 the remains of an old square fort, surrounded, 



hert m t e gn s. g^^gp^ ^t the north-west corner, by a deep moat 

 dug out of the mottled grits. Close to the north-east corner of the 

 moat, and exposed by the denuding action of a spring emerging from the 

 grits, are some boulders of whitish chert imbedded in the grits. These 

 boulders have a very close resemblance externally to the extremely hard 

 limestone occurring at Naicolum, near Ootatoor. 



They contain some fossils, such as a species of UtJiophagns, cast of 

 a terebratula, a coral, and impressions of clavate 



ossi 9 in c er . (club-shaped) spines of a variety of cidaris, which, 



however, have not yet been compared, consequently the age of the beds 

 whence these boulders are derived is uncertain, but they are most likely 

 of cretaceous age. * 



Several more blocks of this cherty rock are to be seen at the foot of 

 the causeway crossing the moat, and fragments are strewed about inside the 

 fort, by which attention was first drawn to the matter. 



The mottled grits occasionally contain numerous pebbles of different 

 varieties of quartz ; and rock crystal, smoky quartz, cairngorms, and ame- 

 thysts are not unfrequently found in the various nullahs running off the 

 grits-plateau near Vellum. These are collected by the native lapidaries, 

 and cut into various ornamental and useful articles, which are sold under 

 the name of Vellum stones. (See Chapter on Economic Geology.) 



presented by the variegated laterite of Shooi-anoor, on the bank of the Ponany river, in 

 Malabar and Kotium (Cottaum), in Travancore, in which latter place I found numerous small 

 but well-rounded pebbles of white quartz imbedded in the eolid laterite. — E. B. F. 



* These fossils were lost in the wreck of the " Aurora" on their way to Calcutta. 



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