10 LAKE: GEOLOGY OF SOUTH MALABAR. 



(4) Garnetiferous gneiss. Quartz is usually the predominating 



mineral in this rock ; but the presence of garnets and 

 the granular condition of the quartz distinguishes it 

 from the quartzose gneiss. The quartz is in small 

 grains and is of a yellowish colour. The amount of 

 hornblende varies, but is not often very great. Felspar 

 is found in small quantities. Garnets are occasionally 

 very abundant, but usually subordinate to the quartz. 



(5) Quartzo-felspathic gneiss. Felspar forms the greater part 



of the rock. Quartz occurs ; but there is very little of 

 any other mineral. 



(6) Haematite and magnetite gneisses. The haematite or mag- 



netite takes the place of the hornblende of an ordinary 

 gneiss ; the rock being usually composed of haematite 

 (sometimes magnetite) in small crystals or in bands, 

 and grains of quartz. The haematite is sometimes con- 

 verted into yellow ochre, and the rock becomes soft and 

 is easily worked. 



(7) Granitoid gneiss. Very rare. About a mile east of the 



hill marked Kawoo on the Atlas Sheet (5 miles north- 

 north-west of Pattambi) is a small exposure consisting 

 of large felspar crystals (compared with the ordinary 

 felspar of Malabar) and blebs of quartz. On the 

 southern slopes of the high ridge north of ManaVkad 

 (Munaur), a true granitoid gneiss occurs, which seems 

 to be intrusive. 

 Of these chief types of gneiss, Nos. 2, 3, and 7 may be intrusive. 

 The rest belong to the main gneissic series. 



Owing to the great extent of country covered by laterite, it is 

 impossible at present to explain exactly the relations of these varieties 

 of gneiss to one another. But some points already made out are 

 worthy of notice. 



In the Beypore River between Nilambur and Eddawannah 

 (Eddamunnah) and thence south to Pandikad, the gneiss is almost 

 ( 210 ) 



