11 
"Marine Clay Zone”. The one hundred and seventy-five mile 
north-south stretch of the Hudson Bay Railway between Amery 
and Churchill is located in this last zone. 
The Marine Clay Zone "is so named because of the wide- 
spread mantle of marine clay deposited during the postglacial 
submergence of the lowland.... Much of the zone is covered with 
a complex network of sluggish dendritic streams, which, however, 
eventually link up with some main drainage channel leading to 
the sea. There are areas, however, that are almost completely 
undrained, the water merely overflowing in periods of thaw or 
rain from one water-hole to the next until some stream is reached. 
Such areas are covered by extensive peat bogs, for the most part 
barren of tree growth of any kind.” 
An outstanding feature of the Coastal Zone is the occur- 
rence of broad tidal flats extending seaward for miles from high- 
water mark. "Low ridges are another feature of the lowland’s 
shoreline.... The ridges appear to develop from offshore bars. By 
repeated wave action, aided by apparent continued crustal uplift 
in the region and a gentle slope of the sea floor — 1 foot in 
200 or 300 yards — these bars are slowly pushed toward the 
shore. ” 
The aerial photographs of Coombs (1954, Fig. 12, Cape 
Tatnam area) and Scoggan (1951, PI. 28 and 1957, PI. 1) illus- 
trate by their patterns of raised shore lines the well known fact 
that there has been considerable uplift along the west coast of 
Hudson Bay following removal of the ice load, estimated by 
Williams (1948) as over 9,000 feet in thickness. Marine shells 
have been found in these beaches between elevations of 200 to 
500 feet. Regular lines of driftwood are found at levels well 
above the highest tides, and Williams reports the finding of a 
walrus skeleton a considerable distance inland, about 43 miles 
south of Churchill. Furthermore, the lower stretches of the 
major rivers are characterized by swift currents and steep banks 
cut through marine clays, limestones, and dolomites. 
Whether or not the land is at present rising at an appreci- 
able rate is another question. Gutenberg (1942), Flint (1952), 
and Lougee (1953) support the view of Bell (1898) that uplift is 
68754 — 4 % 
