10 THE ROYAL SOCIETY OP^ CANADA 



is directed to the character and extent of the oscillations of sea-level 

 relatively to the land, which took place during the Pleistocene, and 

 to whether they were associated with the advances and retreats of 

 the ice-sheet. The Vancouver region is one of the few known areas 

 where conditions are favourable for determining this question, for in 

 this region the stratified deposits interbedded with till are in part 

 marine and hence should furnish some evidence regarding the position 

 of sea-level during the times of formation of the sediments. The 

 character and magnitude of Pleistocene and post-Pleistocene changes 

 in level of the coast of British Columbia and adjacent regions were 

 first described by G. M. Dawson in a paper published in the Canadian 

 Naturalist in 1878. The well-known post-glacial uplift of the coast 

 region of British Columbia has been referred to by several writers. 

 The Pleistocene and post-Pleistocene changes of level in the Vancouver 

 region have been described by Burwash in his report on the area and 

 in the Puget Sound region to the south by J. H. Bretz.'^ Field work 

 by the writer during parts of 1919 and 1920 in the Vancouver region 

 and in the lower part of the Fraser delta showed that a previously 

 unknown marine horizon occurs in the Pleistocene deposits of the 

 region. The marine deposits appear to indicate that a third but 

 probably local advance of the ice-sheet occurred and furnished some 

 definite evidence regarding the position of sea-level relatively to the land, 

 during a period of retreat of the ice, previously to the last advance. 



Topography 



The Vancouver region includes a part of the Fraser delta, which 

 is bounded on the north by the Coast Range, on the east by the 

 Cascades and has its southern limits in the State of Washington. 

 The delta is composite in structure and was built up at different times. 

 The oldest part is Eocene in age, is consolidated and forms the bed- 

 rock of the greater part of the area. The bed-rock is ovçrlain and 

 very largely concealed by Pleistocene and Recent deposits having a 

 maximum thickness as shown by borings of about 1,000 feet. 



The topography of the delta region is in the main low but here 

 and there island-like hills rise to various heights up to 1,000 feet 

 above the sea. The lowest part of the area is occupied by the Recent 

 or modern delta of the Fraser, which is nearly all below the level of 

 high tide and is dyked to exclude the fîood-tidal and freshet waters. 

 It extends inland for 19 miles from the Strait of Georgia to the City 



" Glaciation of the Puget Sound region; Washington Geological Survey, Bulletin 

 No. 8, 191.3. 



