Age of Metamorpkic Rocks, Victoria. 125 



rocks. A second search iie;ii- Onieo was rendered futile by the 

 fact that the boundary between the schists and sediments was 

 not where it was marked on the then current edition (1880) of 

 the Geological Survey map, on the scale of 8 inches to the mile. 

 I accordingly failed to find the junction until too late to use it. 

 That mattered the less, as Mr. A. W. Howitt had already deter- 

 mined that the schists in that case were not altered palaeozoic 

 sediments, but altered plutonic rocks. 



In my second vacation I returned to the north-east to renew 

 this search on the boundary of the metamorphic rocks in Bogong. 

 Snow and fog again hid the junction on the main divide, so I 

 turned northwards to Yackandandah, hoping to find satisfactory 

 exposures at a lower altitude. 



II. — The Metamorphic and Ordovician Hocks at 

 Yackandandah. 



The Geological Survey map of Victoria shows the ordovician 

 and metamorphic rocks at Yackandandah in close contact along 

 Commissioner's Creek and crossing the ridge which separates that 

 valley from Indigo Creek. The saddle between the heads of the 

 two creeks looked a hopeful place at which to tind exposures of 

 the two series of rocks showing their mutual relations. 



Yackandandah is situated on some flats beside the Yackan- 

 dandah Creek, near its junction with Commissioner's Creek and 

 Nine Mile Creek (PL XIX.). To the east is a low track of biotite- 

 plagioclase-granite and granodiorite. To the north-west the rocks 

 are all metamorphic, and they end westward along a line running 

 from south-east to north-west against the ordovician rocks with 

 granitic intrusions. Commissioner's Creek is shown on the map 

 as flowing from the north-west, along the junction between the 

 metamorphic and ordovician serie.s. Nine Mile Creek flows from 

 the south-west, apparently at right angles to the strike of the 

 ordovicians. 



The only literature upon this precise locality to which reference 

 need be made is a paper by Mr. A. W. Howitt, "Notes on the 

 Geology of the Ovens District, with Remarks on the Deep 

 Leads." This paper includes' a brief account of Twist Creek, and 



1 Prog. Rep. Geol. Surv., Victoria, II., p. 78, 1874. 



