ARCH^AN AND PLUTONIC ROCKS. 51 



To the west of Mallapur and about 3 miles west south-west of 



, , ,. .. , Avinmadugu is a narrow band of hornblendic 



Hornblendic schist » 



band west of Mallapur. schist running south south-east to north north- 

 west in the rough felspathic granitoid with an apparently eastward dip. 

 It is very probably a part of the basement trap-flow of the Dharwar 

 system caught into the mass of the granite at the time of the great 

 crumpling and converted into a schist by the great pressure it under- 

 went. Several similar bands of smaller size appear in the jungly tract 

 further west, but could not be mapped because of the want of land- 

 marks among the low rugged ridges in the jungle. 



A traverse of about 3 miles takes one across the belt of trap which 

 unites the Sandur hills and the Copper Mountain ridge, and brings one 

 to the south end of the Hospett sub-division. 



4, The Hospett Sub-division. — The first important show of meta- 

 morphic rock to be seen here is the Toranagal hill 

 (Tornagul), which is of considerable interest. 

 The hill is a bold, rudely conical mass covered with great fallen blocks 

 on all sides, and consists of an immensely coarse porphyritic hornblen- 

 dic granitoid, which also occurs to the eastward and in the bed of the 

 Narihalla (the Sandur river) to the west. In his notes on Toranagal hill 

 my colleague, Mr. Philip Lake, remarks : " In many parts of this rock 

 the longer axes of the (felspar) crystals all lie in one of two directions, 

 these two directions being nearly at right angles to each other". 



The most strikingly porphyritic part of the rock, as seen on the 



north-east slope, appears in form of a band considerably darker in 



colour than the remaining mass of the hill. A similar dark band of 



extra porphyritic character appears at the east- 

 Kuri Kuppa hill. , , __ . :, „ ^ 



ern end of Kun Kuppa (Kooree Koompa) hill 



3 miles to the north-east ; and here the relation of the general porphyri- 

 tic mass of the hill seems to be that the dark porphyry is a distinctly 

 intrusive mass. This was suspected to be the case at Toranagal, but 

 the evidence was not sufficient to be conclusive. 



The bold rocky hill which rises out of the flat of the great Darofi 

 tank to the north of Kuri Kuppa consists of slightly hornblendic 

 02 ( 51 ) 



