1836,] 



Laterile, or Iron Clay. 



115 



degree of trituration would be produced, as to be unfavourable to the 

 preservation of animal exuvise. But the angularity of most of the 

 pebbles forbids this idea. 



Are we to suppose, then, that the laterite is so ancient as to have 

 been formed from the debris of primary rocks, before the existence of 

 life on our Planet h 



Or, is its non-fossiiiferous character a proof of its volcanic origin ? 

 It may be remarked, that the existence of imbedded fragments of 

 crystallized rocks, by no means militates against the eruptive theory. 

 Portions of the rocks, traversed by the volcanic vent, may be thrown 

 out. " The Chevalier Monticelli's invaluable collection of Vesuvian 

 products at Naples, contains a great variety of these substances, 

 among which may be seen fragments of the compact lime-stones of the 

 district, with organic remains in them."* 



Careful observation in many localities, and examination of the 

 laterite in the various forms it assumes, are necessary to enable us to 

 arrive at positive conclusions on this subject. It is particularly desir- 

 able that an examination of the neighbourhood of Beder, in the 

 Hyderabad territory, should be made, with this object in view ; and 

 any of my readers, whose travels lead them in that direction, are par- 

 ticularly requested to collect specimens in illustration of this interest- 

 ing question. Should an iron clay be observed to pass into, or gra- 

 dually change to, any other more compact description of rock, frag- 

 ments should be broken off from various points, so as to show the 

 structure of the two kinds separately, and the change each undergoes 

 on coming in contact with, or changing into, the other. 



We know that boulders travel many hundreds of miles from their pa- 

 rent rocks, so that there need be no difficulty about assigning a locali- 

 ty to the fragments which I have described as imbedded in the laterite 

 and the gravel. St. Thomas' Mount and Palaveram Hills are the nearest 

 to the spot, being about fifteen miles distant. They are composed of 

 varieties of granitic and hornblende rocks. About fifty miles 

 to the N. W. a picturesque hilly outline is visible, the most southerly 

 point of which is the well known Nagary nose. This outline appears 

 as if it was formed by one continued range of mountains ; but, besides 

 the Nagary hills, it includes the Ramgherry ridge, that of Cumbau- 

 cum-droog, &c. Primary rocks, trap in abundance, compact quartzose 

 sand-stone, lime-stone, clay slate, &c. prevail in this direction; also 

 laterite, and conglomerate rocks, or pudding stones. 



Economical uses of the laterite. Vast quantities of this rock are 

 quarried for making roads, for which purpose it is admirably 



* De la Beche's Geological Manual, 3d Edition, p. 138. 



