GLACIAL DEPOSITS OF BACCHUS MARSH. 87^ 



have not, however, observed striae on the granite itself, but in 

 places where the underlying granite has decomposed it has left 

 the imprint of the polished surface and striae on the overlying 

 rock, and these also have a S.W. to N.E. direction. The sam.e 

 remarks apply to the imprint of the striae where the Silurian 

 rock has decomposed from beneath the mudstone or drift, as has 

 also been observed in many places. 



The rock immediately reposing on the Silurian and granite base 

 is composed alternately of conglomerate mudstone and sandstone. 

 These are repeated indefinitely, the dip varying from about 10° to 

 45°, rarely more ; they begin south of the Werribee Gorge with a 

 dip of 8° to S.W. and increase to 10° and 14°, and so continue to 

 the main road. From here the basalt overlies the deposit, on the 

 N.E. edge of which the sandstones dip 15° S.W., increasing to 35° 

 and running up to 40° at the Korkuperrimul Creek, and an 

 approximate average dip across the whole area would, we think, be 

 about 25°. These conglomerates are composed of material chiefly 

 derived from various schists and schistose rocks, granites (very 

 many varieties), gneiss, quartz, jasper, porphyry, fine-grained slates, 

 red, dark, pink, gray, and greenish-white quartzites, and indurated 

 sandstones, some containing waterworn quartz pebbles. 



The mudstone and sandstone rocks contain a similar assortment 

 of stones and conglomerates, which vary much more in size, from 

 the finest mud tu large erratics, though there is generally an 

 arrangement of the material which has classified it somewhat; 

 hence, we have beds of varying grade, of very fine to coarse, and 

 conglomerate, or one merging gradually or suddenly into the other, 

 but all occasionally contain material quite out of the general pre- 

 vailing assortment of any particular bed. Thus all may contain here 

 and there any sort of stone of any size that is found in any of the 

 beds. Even the most regularly arranged sandstones contain occa- 

 sional pebbles up to several feet in diameter, and these may be 

 simply waterworn, flattened and striated, facetted, or highly 

 polished and flattened. This is true of the whole of these beds 

 across the whole area and from top to bottom in the sections, as 

 seen in the cliffs and outcrops. There is a fine section to be seen 

 in the cutting near the gate-house No. 24. This appears to be false 

 bedded. Some of the contained stones are 4ft. in diameter ; these 

 have deflected the underlying strata ; the dip is 15° to 23° S.E. 

 No porphyTy or black slate, or indeed any of the rocks such as are 

 to be found close at hand, have been seen in this glacial deposit in 

 any part, except in the case of some granite. South of gate No. 24 

 there are patches of drift, and the joints run through the beds, 

 cutting through the quartzite bovdders, which have not moved 

 since these joints passed through them. Several fine sections, are 

 to be seen up the flanks of the Werribee Gorge ; some appear to be 

 current bedded; the general dip is to the S.W. The peculiar 

 •vveathering of some beds give them at the flrst glance the appear- 



