SEDIMENTS IN THE DELTA OF ERASER RIVER 117 



average amount of material carried in suspension, as shown by 

 analysis of composite samples of the river water collected triweekly 

 at New Westminster for the period of one year from June 5, 191 9, 

 to June 5, 1920, was 62 parts per 1,000,000, and the maximum 

 230 parts per 1,000,000. The high turbidity of the water is due 

 to comparatively large amounts of very fine material carried in 

 suspension. About half the material carried in suspension during 

 the freshet is composed of silt and clay, a part of which is so fine 

 that it can with difficulty be removed by filtering. The river in 

 its seaward part carries in suspension little material coarser than 

 very fine sand (o.i to 0.05 mm.), but considerable quantities of 

 medium and coarse sand are moved along the bottom. During 

 the freshet the turbid river water flows out over the sea water in 

 the Strait of Georgia and extends for distances of 10 to 15 miles 

 from the mouth of the river. The color line marking the contact 

 of the river water and the sea water is a striking feature in the 

 Strait of Georgia, near the mouth of the river, where it oscillates 

 backward and forward according to the varying influences of the- 

 river, tidal, and wind-induced currents. 



The velocities of the currents in the lower part of the river 

 near its mouth vary greatly with the tides and according to the 

 stage of river water. During the freshet the maximum velocity 

 of the combined river and ebb-tidal currents reaches, but rarely 

 exceeds, 5^ knots per hour. During the low-water stage the 

 maximum velocity is about 3^ knots. The inward-flowing flood- 

 tidal current rarely, even during the lowest stage of river water, 

 equals the outward current, although the rise of tide on the flood 

 is more rapid than the fall on the ebb. The ebb-tidal current is 

 the dominant current because it is reinforced by the river current. 

 The sea water enters the river during the freshet only to a very 

 small extent, and only along the bottom of the main channel. 

 During the low-water stage the sea water at times extends on the 

 flood tide as much as 8 miles up the river. The flood-tidal current 

 in the Strait of Georgia runs north and is the dominant tidal 

 current. It has a maximum velocity of about 2 knots. Slack 

 water is very pronounced in the lower part of Fraser River, because 

 of the lack of a deep channel where it enters the river, which 



