The "olivine nodules" of the basalt Hows and the single 

 crystals or segregations of hornblende or pyroxene are not 

 under review in this paper, though it may be remarked 

 here that Lacroix 1 would consider the former of these as 

 allomorphous antilogous, the latter plesiomorplious anti- 

 logous inclusions. These conclusions are in accordance 

 with the results obtained by Mr. J. A. Thomson, B.sc.from 

 his study of a somewhat similar series of inclusions in the 

 rocks of the Ross Archipelago in the Antarctic. 2 



At Hornsby and at Dundas volcanic necks occur. In 

 both of these during the first epoch of activity the vent 

 was filled with a volcanic breccia. In this were included 

 fragments of the sedimentary formations passed through 

 theNarrabeenand Elawkesbury sandstones, a little bitumen 

 distilled out of the coal measures now three thousand feet 

 below the surface, plentiful fragments of a trachytic or 

 hyalopilitic basalt and of basic or ultrabasic plutonic rocks 

 including at Hornsby essexite. 



ctivity was followed by 

 : basalt, which may have 

 formed a flow on the surface, but now is seen only as a plug 

 with dykes ramifying through the breccia. In this are 



same series of basic and ultrabasic inclusions. The series 

 contains anorthosites gabbros, hypersthene gabbros, olivine 

 gabbros, norites, diallagites, harzburgites, lherzolites, 

 dunites, and the less plutonic types, gabbro porphyry and 

 dolerite. These, together with the essexite, arc considered 

 to be fragments of a highly differentia tod intratellurie 

 crystallisation of the same magma as later gave rise to the 



- the* 



