390 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 5, 



the peculiar white appearance of the stone, and the immense quan- 

 tity of Bryozoa and Foraminifera of Avhich it is composed. The 

 strata are, in fact, very much like chalk-deposits. They have the 

 same a|)pearance when exposed in sections, and contain sheets or 

 layers of flint, with occasionally formations like the potstones of 

 Norwich. I have already described the extent of these beds. They are 

 found throughout the south-eastern portion of the colony of South 

 AustraHa, and they thin out, I believe, about seventy miles due east of 

 the boundary between that colony and Victoria. Of its extent west 

 and north less can be said. Shelly limestones occupy the whole 

 country in those directions for many hundred miles ; but whether 

 they are united with the limestones of Mount Gambler, or whether 

 they belong to the formation I am about to describe, cannot as yet 

 be decided. The object of this paper is to draw attention to another 

 deposit, which is very widely spread in the colony of Victoria. At 

 Hamilton, a town in that colony in about lat. 37° 45' S., long. 

 142° E., there is a remarkable bed of fossils. It occurs at the 

 junction of the Muddy and Violet Creeks, about four mUes south- 

 west of the town. Hamilton is the centre of a volcanic district 

 which possesses several craters. Those who have read the explora- 

 tions of Sir Thos. Mitchell will remember the place better in con- 

 nexion with his description of the extinct volcanoes of Mounts 

 Napier, Ecles, &c. In consequence of the extensive development 

 of vesicular doleritic lava which flowed from them, it is only seldom 

 that a view can be obtained of the undei-l5T.ng rocks. The banks 

 of the creeks are best for the purpose, and, like all Australian 

 streams, these have cut a deep channel for themselves. The town 

 of Hamilton stands upon a plateau probably 300 feet above the 

 sea-level, and rising from it by a series of terraces. The best and, 

 as far as I am aware, the only place for viewing the beds to which 

 I shall draw attention is at the junction just described, where, 

 for the distance of nearly a mile, the following order is observed : — 

 black soil 2 feet ; doleritic lava 3 to 10 feet ; yellow or brown clays 

 to the bottom of the section, about 12 feet. The clay is very soft 

 when first dug, but upon exposure it whitens and becomes hard. 

 In the bottom of the creek one sees occasionally blocks of a very 

 hard stone belonging to the same deposit, but much harder and 

 more flinty from exposure than any part of the clift's, requiring, 

 in fact, smart blows of a hammer to break off a fragment. No 

 beds could be richer in fossils than the whole of the clay. They 

 bleach out upon the banks in the most conspicuous manner. They 

 are easily extracted, but until they are diy are so brittle that the 

 slighest touch destroys them. The shells have more the appearance 

 of a shallow than a deep-sea dej^osit. The most prevalent fossils 

 are more or less encrusted with Bryozoa, Serpida, &c., and though 

 some of the shells are broken and worn, their general character is 

 not such as one would expect in a strictly littoral deposit. Pectens, 

 species of Mitra, Cerithium, Nvx-uJa, CueuUcea, and a Corlmla are 

 the prevailing fossils of the beds. The Bryozoa are numerous and 

 extremely interesting, but of their character I shall speak more 

 in detail at the close of this paper. Some of the specimens have 



