ABSTRACTAge determinations on marine mollusks indicate that the northwestern part of Jones Sound became open to the sea more than 9000 conventional radiocarbon years ago. The presence of postglacial marine features at elevations of up to 130 m near Cape Storm, Ellesmere Island, shows that a significant thickness of glacier ice was present in this area, and the differential uplift of pumice and other materials associated with raised beaches provides convincing evidence that the former ice cover was thicker to the west and to the north.Numerous cross-checks have shown that in such an Arctic environment the organic (collagen) fraction of whale bones gives reliable results, as opposed to the bone apatite fraction, which commonly yields ages that are too young. Marine mollusks also are reliable for14C age determinations, and the evidence available from areas of carbonate rocks in the Queen Elizabeth Islands suggests that the ages of marine mollusks are no more than 350 years older than the ages of contemporaneous terrestrial plants.Near Cape Storm over fifty14C age determinations on driftwood, whale bone, and marine mollusks have permitted the construction of a curve showing the pattern of emergence over the past 9000 to 9500 years. Emergence between 9000 and 8000 years ago proceeded at a rate of 7 m/century, and over one-half of the total emergence (70 m out of 130 m) since the initial incursion of the sea took place during this interval. By 6500 to 4500 years ago emergence had slowed to 0.8 m/century, and for the last 2400 years it has averaged500 years. The concentration of the pumice and the nature of the features associated with it suggest that its deposition may be related to: 1) a eustatic rise close to 5000 years ago; 2) a period of more open water, when wave action and storm surges would have been more effective; 3) a combination of these two factors. The formation of the strandline where the pumice occurs is not believed to be related to a slowing-down or cessation of uplift due to the thickening of ice caps and glaciers.