158 THE VICTORIAN NATURALIST. 



detritus. It reaches to about ioo feet above the water level at 

 one place. Springs sometimes issue at its surface, and other 

 springs whose relation to it is not seen may be concluded to be 

 similarly situated. The numerous wells in the surrounding 

 country also not improbably strike their water in a similar 

 position. (This underlying rock appears at the surface some little 

 distance to the south-west of the lake, on the main road, about 

 three miles from Koroit, and is here also overlaid by tuffs.) 

 Above this are well stratified tuffs and cinder beds — the finer ones 

 compact, the coarser composed of incoherent scoriaceous 

 lapilli. Blocks of basalt, and less commonly of the underlying 

 rock, are found associated with the coarser beds. All the largest 

 noticed were of basalt. Some of these have not only dented the 

 underlying tuffs but cut right through them. The largest noticed 

 was about ten feet in longest diameter exposed. It had crushed 

 through a bed of lapilli two and a half feet thick, and the finer 

 beds below were contorted and sharply fractured, the coarser 

 beds between them being interrupted by the finer ones coming 

 together. The bed to which the block belongs fills in above it, 

 and even thickens over it, so as to be higher at that point. It is 

 very coarse, and contains numerous large pieces of basalt. This 

 is in a road cutting at the south-east of the lake. A quarry on 

 the inside slope, near the same point, also shows many large 

 blocks, most of which, and those in the road cutting, belong to 

 one bed, though they have penetrated to varying distances 

 below it. 



Small quarries are numerous in the upper parts of the bank, 

 and afforded facilities for noting the dip of the beds. The out- 

 ward dips are from 6 to 10 degrees. At two of the quarries some 

 of the beds dip inward toward the lake across the edges of 

 underlying beds. Some of them are curved over, changing from an 

 outward to an inward dip. These inward dips are at the inner 

 sides of the quarries. 



At the pumping station, on the north side of the lake, is an 

 outcrop of basalt, apparently a dyke. The surrounding rock 

 could not be seen, but is probably the Tertiary rock in the lower 

 part at least. This is the only basalt visible besides ejected 

 blocks. Vesicular basalt occurs on the sea coast to the south. 



The lake covers an area of about 850 acres, and is almost 

 circular, with a diameter of nearly a mile and a half, but sweeping 

 out by a gradual curve about a quarter of a mile further at the 

 south-west. It is shallow, except a circular clear water area of 

 about 50 chains diameter at the south-west. This clear water 

 extends from the island to the outer bank. No definite informa- 

 tion as to its depth was obtainable. A portion of the outer bank, 

 for about 30 chains along this clear water area, is low, showing 

 black soil, with recent shells (Haliotis and Turbo). Immediately 



