Palaeozoic Geology of Victoria. 105 



form some of the liighest points of the surrounding highlands. 



The Mount Useful Basalt is only eight miles in a straight line to 

 the Ave^t of the outcrop here described, and yet it is 3300 feet higher. 

 It apparently marks the line of an old valley parallel with the 

 present Macallister, and one que«tion that at once suggests itself 

 is to account for this great difference in altitude. The two alter- 

 natives which seem to be most worthy of consideration are, first, 

 that the two basalts represent floAvs of totally distinct periods in 

 Kainozoic times, and, second, that if of the same age, there has 

 been most extensive differential movement parallel with this line 

 in late Kainozoic times; which view is correct it is impossible to 

 say, but on physiographic grounds I am inclined to favour at any 

 rate a certain amount of dift'erontial movement. This will be 

 referred to again later. 



In this section the rock is seen to be a typical olivine dolerite, 

 with a well- developed ophitic structure, violet brown titaniferous 

 augite enclosing oligoclase. Olivine and magnetite are abundant. 

 The section from the Hickey's Creek area is similar to that from 

 Blanket Hills, but is of a sligbtlv finer grain, ^nd contains more 

 olivine. The specific gi-avity of the latter is 2.81. 



The District of Nowa Nowa. (Map 4.). 



The region here described extends from Nowa Nowa, at the head 



of Lake lyers, northward to within about four milesi of Buchan, a 



distance of about sixteen miles. It lies to the west of the Snowy 



River, and includes the southtrn termination of the great belt of 



"volcanic rocks known as the " Snowy River Porphyries." 



As previously indicated, this region was chosen for examination 

 mainly for two reasons : — (a) To examine certain outcrops of cherty 

 rocks, which had been briefly referred to by Dunn (24) as 

 *' Heathcotian," and (b) to study some of the features of the/ Lower 

 Devonian \olcanic rocks. 



The late Dr. A. W. Howitt (3 and 5) described the latter series 

 as consisting of accumulations of acid lavas and associated pyro- 

 clastic deposits, built up round a line of ancient volcanoes occur- 

 ring along a meridianal fissure. Certain quartz porphyry occur- 

 rences were regarded as probably representing the stumps of some 

 of these old volcanoes. 



Since Howitt's contiihution, about forty years ago, giving a 

 general description of this interesting and important l)elt of rm-ks, 

 there have l^en no important additions to our kiiowlcd^jfi' of tlie 

 reiri(m. 



