Geological Papers. 117 



DID THE ERASER RIVER EVER FLOW THROUGH THE NOOKSACK 

 VALLEY ? 



As has been previously stated, a large estuary or sound once ex- 

 tended up the Nooksack valley from Bellinghara bay to the Sumas 

 mountains. An arm of this sound was found to have extended 

 north through the Sumas valley to the Eraser river, both streams 

 then emptying into the same arm of Georgian Bay. The Fraser 

 estuary or sound also then existed ; the gap in granite barrier to 

 the Fraser's western outlet was then probably partly cut. Probably 

 this estuary and the Nooksack sound were one continuous sheet of 

 water ; the land west of it islands. As the country was gradually 

 elevated above the sea the continuous sound became a swamp area 

 and then dry land. At first the Frazer sent at least a large part of 

 its water through the Nooksack valley to Bellingham bay ; the 

 Nooksack was then a tributary of the Fraser. The part of the 

 Fraser, if any, flowing westward, made its way over a fall where it 

 crosses the granite ledge that closes in the Sumas valley. As 

 the elevation was continued, and the barrier to the western outlet 

 of the Fraser was more and more reduced, a greater volume of that 

 river found its way westward. Finally, as it was the larger stream 

 and consequently could erode faster than the Nooksack, it reduced 

 its channel to the same level at the Sumas pass as the Nooksack 

 was at Lynden. This caused a slackened- water, or laken, region 

 to exist between the two streams. As the Fraser crossed the 

 narrowest part of this lake it soon filled that part of it with sedi- 

 ment, only a small stream connecting the lake with it, and all of 

 the water of river found its way westward. On the other hand, the 

 Nooksack entered the broad, shallow end of the lake, or sound, if it 

 still continued to be a part of the ocean, on leaving the foot-hills, 

 and there deposited its sediment in the form of a semicircular ring 

 ten to twelve feet in height completely through the lake. The tide, 

 coming up the outlet of the lake, or up the sound, if the Nooksack 

 valley still remained a sound, probably aided in forming this ridge. 

 The lowering of the stream below the lake lowered the surface of the 

 lake, and left the ridge dry land, with the Nooksack to the south of it. 

 This ridge is to-day the watershed between the two streams. The 

 facts that lead up to this conclusion are these : (a) Throughout the 

 level area from Lynden to Sumas lake all the wells are drive-wells, 

 ranging from fifteen to forty feet in depth. The strata through 

 which they are driven are sand and gravel of the river type, the 

 depth of which is unknown, (b) The Sumas river, which flows 

 almost parallel with the Nooksack river for several miles, is at the 



