ii8 W. A. JOHNSTON 



prevents sea water from entering the river in flood tide until the 

 tide has reached a considerable height. 



The Recent or modern delta of Fraser River has its head, as 

 defined by the point where the first distributary is given off, at 

 the city of New Westminster. It extends west for 19 miles to 

 the Strait of Georgia and, across its seaward front, is 14 miles wide. 

 The surface of the delta is all below the level of high tide, except 

 in a few places, where the surface of peat bogs is a few feet above 

 the general level and the delta land high enough to be reclaimed; 

 this is diked to exclude the flood-tidal and freshet waters. At 

 New Westminster the river is confined between drift ridges or 

 upland areas, which rise 200 to 300 feet above the river. The 

 upland area south of the river marks the inner edge of the delta 

 and extends from a point on the river 3I miles below New West- 

 minster nearly straight south to Boundary Bay. The delta is 

 bounded on the north by the highland area extending from New 

 Westminster nearly west to Point Grey. In its seaward part on 

 the south side it is interrupted by the highland area of Point 

 Roberts, an island-like drift hill, which has been joined on to the 

 mainland by the construction of the delta. The North Arm of the 

 Fraser flows along the northern border of the delta, the main 

 Fraser flows through the central part, and in the southern part 

 there are a number of smaller outlet channels. 



There can be no doubt that the materials composing the delta 

 have been transported to their present resting-place very largely 

 by the river; for it has been shown that the river transports con- 

 siderable material during its freshet stage, and there is no other 

 apparent source for such a large amount of material. A small 

 part, however, has been and is being derived from wave erosion 

 of the shores, chiefly of the highland area of Point Roberts. A 

 large part of the material composing the delta is sand and silt 

 derived by stream erosion from the vast accumulations of glacial 

 drift which border the banks of the Fraser and Thompson rivers 

 for long distances above the canyon of the Fraser, in smaller part 

 from erosion of the bedrock (granite) in the canyon of the river^ 

 and from erosion of the drift deposits in the upper part of the delta 

 area. 



