128 W. A. JOHNSTON 



delta at the north end of the lake are greatly increased. This 

 appears to be borne out by the fact that in places the sandy layers 

 are thinly laminated. 



SUMMARY OF CONCLUSIONS 



The tidal flood-plain deposits of the Fraser River are char- 

 acterized by a very thin lamination which is tidal in origin. The 

 seasonal character of the bedding is shown in places by layers of 

 vegetable material and in other places by alternations of silty 

 layers and sandy layers, both of which show tidal lamination. 



The alluvial flood-plain deposits of the Fraser are characterized 

 by seasonal layers of silt and vegetable material. 



Neither the tidal nor the alluvial flood-plain deposits show to 

 any marked extent gradational lamination. 



The fore-set beds of the Fraser Delta, deposited in sea water, 

 are characterized by a thin lamination which is the result of the 

 combined action of fiocculation in sea water, river and tidal cur- 

 rents, and slack water. The beds have in places marked cross- 

 bedding as well as inclined bedding. The fine-grained bottom-set 

 beds are thick and without lamination, because of the effect of 

 fiocculation in sea water. 



The Pitt Lake Delta deposits formed at the south end of Pitt 

 Lake (a tidal fresh-water lake) are characterized by a very thin 

 lamination and by a banding, both of which are probably tidal in 

 origin. The fine-grained bottom-set beds have a very thin and 

 gradational lamination, which is due to tidal action and to the 

 absence of fiocculation in fresh water. They show no definite 

 evidence of seasonal banding. The deposits now forming in the 

 delta at the north end of Pitt Lake have a tidal lamination and 

 probably also a seasonal banding. 



A conclusion which may be drawn from the fact that the fine- 

 grained sediments deposited in salt water are not laminated, 

 because of the effects of fiocculation, while those formed in fresh 

 water are, is that fine-grained sediments which are evenly and 

 gradationally laminated are fresh-water sediments in origin or, if 

 marine in origin, are glacial; for it is probable that sea water would 



