33S 



On the Lateritic Formation. 



[Oct. 



a larger proportion of quartz into laterite. Quartz being more difficult- 

 ly indecomposable, being almost as it were the undying por.tion of the 

 rock, forms a nidus or nest — it constitutes the more solid ingredient, 

 and the felspar and liornblende the softer portion. In almost every spe- 

 cimen of either lithomarge or laterite. small crystals of quartz are found ; 

 and here is another striking similarity — these crystals being the only 

 parts of the original rock resisting decomposition. As in some measure 

 a proof of the views now entertained, I may refer to the decomposed 

 rock of wdiich the Conoor bridge on the Neilgherries is built — it appears 

 to be in that medium state between lithomarge and laterite ; it is quite 

 solid, and, although not cavernous, has much of the appearance of 

 laterite. It is a rock exemplifying the fact of catching nature in the 

 act, not, of coiu'se, of formation, but of decomposition. It is in that me» 

 dium condition, where a farther decomposition would hav'e produced a li- 

 thomarge, or a preponderance of quartz would have given it all the decided 

 characters of laterite. I am endeavouring to prove the connection be- 

 tween lithomarge and laterite, and to shew, that the cause which leads 

 the original rock to decompose into either of these conditions is the 

 same. Wherever laterite is found in great abundance the hills are of 

 a rounded and lithomargic character, and there is a peculiar family 

 likeness between the rounded hills of Coorg, the Neilgherries, Manan- 

 toddy above the western ghauts, and all the hills from the bottom of the 

 ghauts to the sea— from the foot of the Heggula pass to within a mile 

 or so of Cannanore. The greatest victory to be gained by science in the 

 field of nature, is through arrangement ; but the error daily committed, 

 is that of seeing order and arrangement where such do not exist, of laying 

 nature down, and fixing her there by means of a little gum and water. 

 I have no arrangement of lateritic ro;:ks to offer, and would not be 

 justified in even attempting to form one, as it requires more extended 

 observation and more science than I possess ; but I might perhaps ven- 

 ture to arrange those in my possession into tlie lithomargic and the 

 quartzose. It is as well here to remark, that in the lithomargic kind 

 quartz is not excluded — in the last it is the principal ingredient. The 

 cavernous, tubular structure of laterite is one of its peculiar features, 

 and the consideration of the cause or causes leading to this state may 

 ^n some manner explain my views. I was long puzzled to account for 

 it except in one way — the falling out of the decomposed felspar : but in 

 those specimens of the harder and more quartzose kind, and where it 

 approached in a certain degree to a sort of iron-stone, and no felspar 

 seemed to enter into its formation, I was much at a loss for an explana- 

 tion. There are two modes, besides the one alluded to, in which this 



