THE VICTORIAN NATURALIST. 61 



scooped into hollows as we see it in the cutting. This denotes a 

 considerable lapse of time between the two deposits. 



If the deposit on the top of the basalt be now examined, we 

 find a great deal that will interest us in its physical geology, but 

 which time will prevent our noticing. There is a rich fossil bed 

 which immediately overlies the basalt, except in a few places 

 where it is underlain by a deposit of coarse white sand. The 

 red ochre colour of the fossil-band makes it easily recognizable 

 even at a distance. As is usual in ironstone, we get mostly the 

 casts of fossils, and not the fossils themselves, and this, of course, 

 makes their identification difficult. The forms are all marine, and 

 some are almost indistinguishable from living types. A few forms 

 have been described, but collectors will continually find them- 

 selves at a loss for the names of their specimens. Some named 

 specimens will be found in the National Museum. Judged by the 

 fossils the beds are slightly younger than those of Brighton, and 

 are the marine representatives of the middle gold drifts. The 

 underlying basalt is, in some places in the valley, stated to be 

 underlain by a clay bed with fossil leaves in it, but I have not 

 seen this deposit. The late R. Brough Smythe informed me 

 Murchison stated this clay to be, probably, of mioccne age. From 

 data gathered elsewhere the age of this, the older basalt, is 

 miocene. Now that we have seen the exact position of the fossil 

 bed — namely, immediately overlying the basalt — we know where 

 to look for it in other places. A similar section to the one in 

 this cutting is displayed in the cutting on the left side of the creek, 

 on the road crossing the stone bridge, close to where we examined 

 the silurian rocks. Near the top of the hill, where the cutting is 

 about 15 feet deep, we find the same spotted clay or decomposed 

 basalt, with the same ferruginous gravel on the top. Close to the 

 junction of the two a careful search will be rewarded by a few 

 fossils, such as cowries and other small shells. The two deposits 

 were evidently continuous, and the whole of the valley between 

 has been carved out by the stream. 



The iron, which has stained the gravels their rusty colour, was 

 in all probability derived from the older basalt. Close to the 

 semaphore, in the railway cutting, it will be seen that the decom- 

 posed basalt is penetrated in all directions by sheets of ironstone, 

 so that some fragments may be picked up which look almost like 

 a loaf of bread in structure. This is a secondary product. The 

 iron has been washed out of the overlying gravel and penetrated 

 the basalt again. All over the surface of the park will be seen 

 small rounded grains of pea-iron ore. They look as though they 

 are waterworn pebbles, but they are concretious, and when broken 

 open usually have a grain of sand in the middle. This form of 

 ironstone is very characteristic of our recent deposits, especially 

 in the neighbourhood of basalt. 



