26 



LAKE : GEOLOGY OF SOUTH MALABAR. 



T?r : ^p^?^r 





At Kolattur there are cases where the lateritisation of the gneiss 

 does not take place 

 along its laminae, 

 but in a spheroidal 

 fashion (Fig. 15). 

 The gneiss is more 

 compact than at 

 Shoranur, and the 

 spaces between 

 the spheroids are 

 full of laterite, the 

 spheroids remain- 

 ing in their origin- 

 al positions. The 

 layers of gneiss 



that are beginning Fig. 15. Spheroidal lateritisation of gneiss. 



to scale off are partially lateritised. 



Near the hill of Turitiancoon, about 5 miles north of Ang^di- 

 puram, is a small plain, the surface of which is composed of alternate 

 bands of laterite and gneiss. The bands run in the same direction 

 as the bedding and lamination of the gneiss ; and the more easily 

 lateritised bands have been converted into laterite while the others 

 are unaffected. 



This is not uncommon, and a precisely similar example may be 

 seen about a mile north-west of Parli Station. 



These observations all go to prove that some of the valley 

 laterite has been formed by decomposition in situ of the gneiss. 

 But there is quite as good proof that some of it is of fluviatile 

 origin, and its distribution seems to show that this is the case with 

 the greater part. 



A well-marked long band of laterite follows the course of the 



Ponnani River from near Pdlghdt to Pattambi. It is bounded to 



north and south by gneiss. A section through Mangara (Muncurray) 



shows the relation of the laterite to the river (Fig. 16, PI. VI). It 



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