656 REPORT— 1897. 



valleys, but often eroded, or entirely swept away by the rivers since the Glacial 

 period in clearing out their channels anew. From the facts at hand it is evident 

 that a mantle of these materials of variable thickness must have occupied the 

 vsrhole region in the later Tertiary period, however, and that denudation from the 

 Pleistocene ice and fluviatile action before and since has left only remnants of it 

 to the present day. 



In reference to the precise age of these beds in Eastern Canada, no evidence 

 seemw yet to be available. At the western base of the Green Mountains, near 

 Brandon, Vermont, certain beds were discovered many years ago closely resembling 

 those of the Chaudiere valley of pre-Glacial date. Lequereux, who studied the 

 vegetable remains which they contained, referred them to the Miocene.* 



The manner in which the rocks decompose and yield these indigenous products 

 is a question which requires fuller treatment than can be accorded to it in this 

 paper. Decomposition seems, however, to be mainly of two kinds — mechanical and 

 chemical. The most important is doubtless that due to precipitation and to the 

 action of the carbonic acid of the atmosphere. Changes of temperature have also 

 tad a very great influence, especially in Eastern Canada, producing contraction 

 and expansion of the rocks, and thus causing numerous joints and fissures into 

 -which water and disintegrating agents would find access. Decomposition cannot, 

 towever, have proceeded at as rapid a rate in this country as in tropical regions. 

 The mantling of the earth's surface with snow and the freezing up of the super- 

 ficial deposits for five or six months every year would have a conservative effect, 

 and check the action of the disintegrating forces. 



The general aspect of the dry land in Eastern Canada previous to the Glacial 

 period must have been nearly similar to that of the region south of the glaciated 

 2one in North America, though the superficial beds may not, for the reasons stated 

 above, have been as deep. The facts show, however, that rock decay has been in 

 progress for long ages in this country as in other parts of the earth, though 

 apparently with diminished eifect. 



SATURDAY, AUGUST 21. 



The following Papers and Eeports were read : — 



1. Note on certain Pre-Camhrian and Cambrian Fossils supposed to be 

 related to Eozoon. By Sir W. Dawson, F.R.S. 



This note relates to fossils referred to in the discussion of the author's paper 

 'Dn Eozoon at the Liverpool meeting last year, and subsequently re-examined by 

 him. It relates to the genera Cryptozoon of Hall, Archceozooti of Matthew, and 

 Girvanella of Nicholson {Streptochetus of Seeley). All three are now known in 

 their structures, and have been found in beds ranging from the Lower Cambrian 

 downward. They all seem to be animal forms of low and generalised structure, 

 and probably Protozoa. The specimens referred to can be seen in the Peter 

 Pedpath Museum of McQill University, Montreal. 



2. Note on a Fish Tooth from the Ujyper Arisaig series of Nova Scotia. 



By J. F. Whiteaves. 



The only indication of the existence of vertebrate animals in the Silurian rocks 

 of Canada, that has yet been recorded, is a single specimen of a Pteraspidian fish 

 ■discovered by Dr. G. F. Matthew in the Nerepis hills of southern New Brunswick 

 in 1886. This specimen, which consists of the rostrum, the lateral cornua, the 

 •dorsal and ventral scutes, and some other plates of the anterior armature of the 



* Geology of Canada, 1863, p. 929. 



