l8 LAKE: GEOLOGY OF SOUTH MALABAR. 



no doubt due to percolation of water from above, but they are never 

 found except when the laterite is in contact with water below. 



The vesicular laterite sometimes, in spite of its porous character, 

 puts on a massive appearance and may be jointed, the joints being 

 vertical and running in two sets at right angles to each other. 

 Usually these joints do not appear except at the edge of a cliff; 

 but sometimes, as on the hills north of Kadananjeri 1 (half way 

 between Calicut and Kondotti), they are found on a level surface well 

 away from the edge of the cap. 



At other times the laterite is laminated, usually parallel to the 

 lamination of the gneiss of the neighbourhood ; and sometimes it is 

 pierced by quartz laminae and veins rising from the rock below. It 

 not uncommonly includes angular blocks of gneiss or, still more 

 often, of quartz ; and occasionally it contains well-rounded pebbles. 

 The blocks of gneiss may be of almost any size, from the largest to 

 the smallest. 



The pellety laterite is usually much more solid than the other, 

 and consists of small irregular nodular-looking pellets of red oxide 

 of iron cemented together by similar material. There are no vermi- 

 cular tubes, and the rock has a higher percentage of iron than the 

 unexposed parts of the vesicular variety. Probably the percentage 

 is nearly the same as that of the tube-walls of the other form. 



The mode of formation of this variety is not difficult to follow, 

 and in many places the process may be seen going on. The exposed 

 parts of the vesicular variety, after the contents of the tubes have been 

 washed out, slowly break up. The tube-walls break into little sub- 

 angular irregular pieces. Very often where a large level surface of 

 laterite is exposed, it is found to be covered with these little masses; 

 and these little masses are precisely like the pellets forming the 

 main part of the pellety laterite. They are washed away by the 

 rain or rivers and deposited at a lower level, where they are re- 

 cemented together. It is chiefly on old river terraces that this form 

 of laterite is found. 



J Not marked on map. Lies about a mile north-west of Chelimbur. 

 j 2l8 ) 



