THE GONDWANA FORMATION 247 



nouvelle et, dans le cas oil elle serait indigene, ne constitue-t-elle qu'une exception 

 dont il serait en tous cas int^ressant, au point de vue theorique, de pr^ciser la 

 port^e ? " 



The question as to the general relation of the eruptive rocks of the great horst 

 to those of the South American and Antarctic Andean rocks will be further discussed 

 in the summary at the end of this work. 



III. METAMORPHIC ROCKS 



It has already been stated that these rocks in part are probably of Pre-Cambrian 

 age. There can be little doubt that in part they represent sedimentary rocks, 

 possibly of Cambrian or Ordovician age, which have been metamorphosed through 

 the intrusion of large masses of granite. Mawson describes an erratic specimen 

 from Marble Point, 5 miles north of Cape Bernacchi. This rock he terms epidotised 

 granite. As regards sediments of metamorphic origin which may belong to the 

 period of time intermediate between Pre-Cambrian and Gondwana, it is possible 

 that the saccharoidal marbles and tourmaline schists between Cape Bernacchi 

 and Marble Point represent Cambrian limestones locally metamorphosed by granitic 

 intrusions. At the same time there is equal likelihood of their representing Pre- 

 Cambrian limestone beds. On the whole we are disposed to provisionally group 

 these metamorphic saccharoidal marbles and their associated schists as Pre- Cambrian. 



GONDWANA 



BEACON SANDSTONE FORMATION (in part) 



The Beacon Sandstone formation in the type area of the Ferrar Valley, where 

 it was first described by H. T. Ferrar, is shown to have a thickness of at least 1500 

 feet, and consists mostly of sandstone regularly, and almost horizontally, bedded, 

 varying from fine to coarse occasional bands of conglomerate, with a few strata of clay 

 shales and argillaceous limestone. Through the courtesy of Dr. J. T. Prior, one of 

 us (T. W. E. D.) was able to examine under the microscope slices of this limestone. 

 Its original structure had sufiered much from recrystallisation, and no trace whatever 

 could be seen in it of any organisms. The following is an ascending section as given 

 by Ferrar : — 



100 feet dolerite which caps the sandstones. 



200 „ yellow sandstones. 



100 „ sandstones with occasional yellow bands. 



100 ,, sandstones with ferruginous concretions. 



200 ,, yellow sandstones. 



100 ,, sandstones with cylindrical casts. 



200 ,, yellow sandstones with ferruginous concretions. 



