8 



probably by plutonic and volcanic action ; and, thirdly,''; in ex- 

 tensive sub-aerial denudation when the crests of the curves 

 were removed. 



Miocene Tertiaeies. 

 Prom the laying down o£ the Upper Devonian sediments to 

 the sealing up o£ the 3iiocene valleys by the lava-flows, there is 

 a manifest break in the continuity of geological formation, 

 which can only, I think, be accounted for by supposing, either 

 that powerful denudation has removed any remnants of 

 Mesozoic formations, or that volcanic activities, which termi- 

 nated the Devonian period, raised the land surface to above 

 sea level so that no Mesozoic sediments were deposited. To the 

 north of the line of section, are other and more extensive lava- 

 flows covering Miocene river-beds, as at Bogong High Plains, 

 6,000 feet above sea level. The extent and geotectonic features 

 of this area, indeed, of the whole of the area embraced by 

 the Tertiary basalts, have been so ably delineated by the Grovern- 

 ment geologist, Mr. Murray,* that I must refer those desirous 

 of obtaining valuable information on these areas to that gen- 

 tleman's published reports. It may, however, be interesting 

 to note that according to the petrographical examinations by 

 Mr. Howitt, no good distinction exists either in structure or 

 composition between the so-called older and newer basalts of 

 Victoria (among the latter have been classed the basalts of the 

 Western District). To those desirous of obtaining complete 

 scientific knowledge of the structure and composition of the 

 intrusive rocks invading the metamorphic areas, Mr. Howitt's 

 contributionsf to the subject will be specially valuable, leaving 

 nothing to be desired on the score of accurate information of 

 the structural and stratigraphical relations of the rock masses 

 within the areas he has examined. As this gentleman is at 

 present assiduously working at the area south from the line of 

 section described in this paper, his determinations of the com- 

 position of the dykes and intrusive masses may be looked for- 

 ward to with considerable interest. In the meantime, the in- 

 formation supplied may not be without interest to geological 

 readers. 



* "Geol. Sur., Victoria, — Dargo and Bogong," vol. 5. 

 t " Granites and Diorites of Swift's Creek," by A. W. Howitt, F.G.S. 

 Trans. Koy. Soc, Victoria. 



" Piocks of Noyong," Trans. Eoy. Soc, Victoria, 1883. 



