and Igneous Rocks of Ensay. 117 



The Upper Devonian sediments, which are next in order, 

 are entirely discordant with those of Middle Devonian age, 

 and are in most places but little disturbed from a horizontal 

 position. 



The four groups — Lower and Upper Silurian, Middle and 

 Upper Devonian — all show a marked decrease in mineralisa- 

 tion in the ascending order. Some of the nearly horizontal 

 beds of the Iguana Creek Upper Devonians are little more 

 than indurated clays or friable sand-rock. 



So much in brief as to the sediments. Between the 

 acutely folded Silurian and the much less folded Middle 

 Devonian sediments there intervenes, in the chronological 

 arrangement, as in the field, an immense thickness of igneous 

 rocks, whose lower members rest upon the denuded edges of 

 partially metamorphosed Silurians, while the upper beds 

 pass as tufas into the Middle Devonian marine limestones of 

 Buchan.* 



On the grounds which I have now very briefly stated, I 

 place the folding of the Silurian sediments and their invasion 

 by plutonic masses at the close of the Silurian age. The 

 Devonian volcanic rocks clearly followed this invasion, and 

 I think that they may prove to have been connected with a 

 second great series of younger igneous rocks, which are to be 

 found in different parts of Gippsland, rising through both 

 the Silurian sediments and the older plutonic masses. The 

 younger igneous rocks are in most cases porphyritic, and I 

 note, as instances, The Sisters and Mount Leinster,near Omeo, 

 and Mount Taylor, near Bairnsdale. These younger plutonic 

 rocks are probably all older than the Upper Devonian age, 

 for the last named mountain is still capped on its denuded 

 summit by nearly horizontal beds of the Iguana Creek 

 series.-)- 



Of the formations which I have now noted there are found 

 at Ensay only the Silurian sediments, the older plutonic 

 masses, and the metamorphosed representatives of the 

 former. The later plutonic rocks are not met with, nor any 

 of the Devonian sediments. 



* " Notes on the Devonian Eocks of North Gippsland" — Geological Survey 

 of Victoria, Progress Eeport, I. , p. 117. "Notes on the Diabase Eocks of 

 the Buchan District" — Transactions of the Eoyai Society of Victoria, Vol. 

 XVIII., p. 7. 



t Geological Survey of Victoria, Progress Eeports, II. p. 63, and in. p. 211. 



