272 



Geology. 



The oldest exposed rocks are the granitic rocks of the 

 Coast Range batholith, which border and underlie the 

 delta on the north. 



Remnants of once more extensive Lower Cretaceous 

 rocks form some of the hills in the upper part of the delta, 

 and around these the more recent deposits were laid down. 



Virtually the whole of the delta, with the exception of 

 those parts covered by the Cretaceous remnants, is believed 

 to be floored by stratified rocks of Eocene age, which 

 are referred to in the literature as the Puget group. 

 They consist of little disturbed beds of conglomerate, 

 sandstone and shale which were laid down by the ancient 

 Fraser river in an estuary of the sea. They have a thick- 

 ness of about 3,000 feet in Canada, but are much thicker 

 in the State of Washington. They contain a variety of 

 plant remains and some small seams of lignite. 



The Eocene beds suffered erosion throughout the re- 

 mainder of Tertiary times, but towards the close of the 

 Glacial period were overlaid throughout by sands, gravel 

 and till. These deposits now constitute broad, flat- topped 

 plateaus about 400 feet (122 m.) high, which were once 

 continuous as the late Glacial delta of the river. They 

 have, however, since been dissected by the present stream, 

 as a result of post-Glacial elevation. This process of 

 dissection is related to the strong terracing of the Glacial 

 deposits in the upper part of the Fraser river. 



A modern delta is at present being formed by the river 

 and pushed seaward into the Gulf of Georgia. 



REFERENCES. 



Bowman, Amos G.S.C. Vol. Ill, p. 66 A. 



Daly, R. A G.S.C. Vol. XIV., p. 42 A. 



LeRoy, O. E G.S.C. Report of a portion of 



the Coast of British Columbia and 

 adjacent islands, 1909. 



