382 Albert V. James: 



Palaeozoic Conglomerates. — The four palaeozoic conglomerates: 

 in this area have been carefully described by T. S. Hart (5). C^, 

 the most northerly, is wrongly coloured tertiary in one of the three 

 quarter sheets. It has been pointed out (6) that this conglomerate 

 has been so indurated by thermal metamphorism that the matrix 

 is as hard as the old quartzite pebbles, and thus the pebbles do not 

 weather out. 



Ihe southern exposure C^ can be picked up in a runnel on the 

 cliff about ,80 ft. above the stream. It is not altered to the extent 

 that C4 is. 



Ca shows the clay bands much distorted by differential pressure,, 

 as they are in the Italian Cutting, Daylesford (8). 



d is the largest of the four conglomerates. 



T. S. Hart (6) puts forward various reasons for considering it 

 an Ordovician glacial conglomerate. His conclusions appear in- 

 correct. The following is a summary of the reasons given on which 

 he based his conclusion : — 



(1) A part of the conglomerate is a mixture of pebbles and 



fine clay. 



(2) The strata are much disturbed in places. 



(3) The matrix is angular. 



(4) Some pebbles are facetted and striated. 



(5) Fossils are absent on account of severity of the climate- 



at that period. 



The writer carefully weighed these points, but was forced to> 

 discard the theory of the glacial origin. A mixture of pebbles and 

 clay can be formed in other ways than by glacial action, and the 

 disturbance of the strata appears to be the unconformable junction 

 of the Ordovician and Silurian. The presence of the striations on 

 an insignificant percentage of the pebbles can be accounted for 

 by the fact that wlien conglomerate bands are folded under pres- 

 sure, the hard pebbles grind against and scratch one another. 

 Facetted pebbles were not * common in this conglomerate, and 

 there was quite as large a percentage in the river conglomerate 

 as in the ancient collection. On examining under the miscroscope, 

 the matrix from conglomerate C and comparing it with material 

 taken from other strata, it did not appear to be more angular 

 than the latter. It lias been shown' already that life Avas abundant 

 in the seas in that age. 



The direct evidence against this glacial theory is : — 

 (a) llie general linear arrangement of the pebbles. 



