GEOLOGY OF THE AREA. r 2g 



laterites, though as a rule it happens in this area that the distinction 

 is fairly well marked. The terrace and valley laterites lie nearly flat, 

 while the talus laterite covers very steep slopes. 



In Fig. io the laterite covering the slope between the plateau 

 laterite and the terrace laterite is clearly talus fallen from the 

 former. In Figs. 5, 8, &c, it will be seen that the laterite runs up the 

 sides of the hills above the general level of the valley-floors. It is 

 here, no doubt, mixed with talus from above. 



The most important taluses are found on the south side of the 

 high ridge east of Poothur of the map. The height of this ridge 

 above the valley to the south is about 300 feet, and the whole slope is 

 covered by a sheet of laterite. The western termination of this ridge 

 is also partly covered by talus, but the gneiss of the hill appears in 

 many places. 



Origin of Laterite in Malabar} 



As we have seen, there are two chief varieties of laterite in Mala- 

 bar. The mode of origin of the pellety form has already been de- 

 scribed. The other is the result of concretionary action taking place 

 in a ferruginous clay, and it now remains to determine how far this 

 clay is of detrital origin, and how far it has been formed by the alter- 

 ation in situ of gneiss. Evidence has already been given that some- 

 times laterite has been formed by the one process and sometimes by 

 the other, but a few critical sections have still to be described. 



A few hundred yards south of Ferokh (Ferokkabad) Railway 

 Station there is a cutting through a low laterite hill. From its 

 position, this laterite appears to have belonged to a terrace on the 

 seaward side of the western edge of the plateau. It is now quite cut 

 off from the plateau and is too low ever to have belonged to the 

 plateau itself. 



The upper part of the face of the cutting (Fig. 19, PI. VII) is laterite 

 with a rather low percentage of iron. It is in some places distinctly 

 bedded, or at least laminated horizontally. Below this is a thin 



1 For remarks on the origin of laterite in other areas and a history of previous 

 views on the subject, see Appendix. 



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