Chap. I.] ECONoivric Gi':or,ooY. 205 



The same remark will apply to most of the limestones of the Oietace- 



ous rocks, which are, however, quarried to a coii- 



Cretaceous limestones. 



siderable extent, for the construction of small vil- 

 lage imgodas and chuttrums. The chief locality from which stone for 

 this purpose is procured, is the ridge at the base of the Ootatoor group, 

 which extends from Purawoy to Vylapaudy ; much is also obtained from 

 the ridges of coral-reef and sedimentary limestones, similarly situated, 

 at Assoor, Maravuttoor, Cullpaudy, Sirgumpoor, Varagapaudy, and 

 many other places further to the Southward. The ridge of shell 

 limestone between Garoodamungalum and Alundanapuram, is ano- 

 ther favorite locality, and indeed wherever a band of limestone or 

 calcareous grit crops out heaps of fragments and lines of wedge 

 holes show that the spot is occasionally resorted to by the native 

 quarryraen. 



These limestones are of various degrees of purity. Specimens of the 

 coral-reef limestones, analysed by Mr. Tween, gave from 95 to 98 per cent, 

 of carbonate of lime. The Olapaudy limestone, above mentioned, is 

 somewhat less pure, and some of the calcareous grits, such as those in 

 the upper part of the Ootatoor group, between Kolokaunuttom and 

 Sliutanure, do not contain probably more than 20 per cent, of calcareous 

 matter. The coral reef and purer sedimentary limestones have been fully 

 described above (page 52). They are tolerably compact, but as may be 

 Been in the coping stones and drip stones, and the exjDosed mouldings of 

 kovils, built of these rocks, they are but ill qualified for exposed 

 exteriors, where they rapidly yield to the heavy tropical rains. These 

 stones being soft, and easily worked, are used to a considerable extent 

 by the natives of the district for rice-mortar? and water troughs. 



The sandstones of the Cuddalore group are quarried to a small 



extent at Velur, near Verdachellum, and at 

 Sandstones. 



Vellumpaleyam, on the bank of the Guddalum. 



■yhe stone is compact, moderately fine in grain, and being jointed in two 



