64 THE VICTORIAN NATURALIST. 



NOTES ON THE KERRIE CONGLOMERATES. 



By T. S. Hart, M.A. 



(Read before the Field Naturalists' Club of Victoria, 8th August* 



1892J 



The parish of Kerrie lies between Riddell's Creek and the Emu 

 or Bolinda Creek, and extends from the Dividing Ran^e, near 

 Mount Macedon, to Lancefield Junction. Extensive beds of 

 conglomerate occur to the north of Riddell's Creek, beginning 

 about a mile and a half above the township. Further north other 

 patches occur as far as the Black Range, on the north-east side of 

 the Emu Creek. They are marked on the geological maps as 

 thin cappings and outliers, and are mentioned by Mr. Selwyn in 

 his " Geology of Victoria ; " but, so far as I am aware, no further 

 notice has been taken of them. In these notes I intend to give 

 a short account of their main features, as I saw them in the 

 southern part, near Riddell's Creek. Very fine sections occur 

 on two tributaries of Riddell's Creek (in sections 109 and 118 of 

 the Parish of Kerrie) and on the neighbouring ranges. The lowest 

 level at which I saw them was about 1,240 feet, and the highest 

 2,000 feet above sea level. 



The conglomerate consists of a hard cemented mass of pebbles 

 of a grey subcrystalline sandstone and brown micaceous sandstone, 

 with a little quartz. The pebbles are for the most part rounded, 

 but many of the smaller ones are angular. They vary in size 

 from sand up to over 2 feet in diameter. Many of the pebbles 

 contain thin bands of quartz. Associated with the conglomerates 

 are small, irregular beds of gritty sandstone, which do not appear 

 to be very persistent. At one place beds of sand and clay occur, 

 with small scattered pebbles, up to 2 inches in diameter. 



The bedding of the sandstones is irregular, but appears, on the 

 whole, to be nearly horizontal. At one place on Riddell's Creek 

 the conglomerate seems to form thick beds, dipping towards the 

 south-west. Large pebbles are more common in the lower parts, 

 and large, long-shaped pebbles seemed as a rule to be nearly 

 horizontal. The whole deposit is much intersected by joints, 

 which cut straight through the pebbles. The main joints run N. 

 io° W., and are vertical. Individual stones are often fractured, 

 but the parts not separated. 



These joints have a great influence in the weathering, and con- 

 sequently on the nature of the hills and valleys. The sandstones 

 and gritty parts are easier to wear away than the conglomerate, 

 and the joints both allow the entrance of water and the breaking 

 away of large masses of rock. This leaves the face of the joint 

 as a smooth, vertical cliff, sometimes as much as 40 feet in height. 

 Sometimes another cliff will rise above this, a little further back ; 

 so that the side of the hill rises by a series of steps. At one place 



