Postelsia 53 
Both the San Juan and Gordon rivers find 
outlet into San Juan harbor about 3-4 kilo- 
meters apart. The former stream through al- 
luvial deposits and the formation of an extensive 
sand bar at its mouth has shifted its outflow 
from its one time channel so that at low tide it 
flows into the Gordon a short distance above the 
mouth of the latter. Between the original out- 
let of the San Juan and the place where they at 
present both reach the harbor, there has been built 
up a considerable alluvial plain which now sup- 
ports a very heavy forest mostly of spruce but 
with scattered trees of cedar and of hemlock. 
The Gordon river valley widens out shghtly 
in its lower part. The heavy timker of the slopes 
reaches down to the edge of the channel, except 
near the mouth of the river where narrow strips 
of meadow land are found on either side. Again 
the typical forest trees are Picea sitchensis, 
Thuja plicata, Tsuga heterophylla, and Abies 
amabilis. Here Pseudotsuga Douglasii is oc- 
casionally met with even in the lower reaches of 
the valley, and along the river bank occur Acer 
macrophyllum as well as one or two species of 
