| Summary: | Marine geophysical surveys in Port au Port Bay, west Newfoundland, have revealed more than 50 m of Quaternary fill in East Bay and lesser amounts in other basins. Six seismostratigraphic units have been identified and interpreted as follows: (1) an acoustically unstratified unit, including till and other ice-contact deposits, representing the products of deposition or loading by grounded glacial ice or of other ice-contact processes; (2) a crudely stratified unit, believed to be mainly ice-contact or ice-proximal sand and gravel; (3) a conformably stratified unit, interpreted as glacimarine and early paraglacial sandy silt and clay; (4) a weakly-stratified to acoustically transparent unit consisting of postglacial mud; (S) a wedge-shaped unit dominated by clinoform reflections, representing postglacial deltaic sand and gravel in submerged terraces off Fox Island River; and (6) thin wedges of acoustically stratified deposits, considered to represent transgressive shoreface, late-delta, and tidal units of sand and gravel. Radiocarbon determinations on paired bivalves from unit 3 indicate a range of ages from 13.3 to10.8ka, implying initally rapid late- and post- glacial sedimentation. Paraglacial sediment supply from small glaciated river basins is known to be maximized during and shortly after deglaciation and to decrease rapidly thereafter. This is consistent with an interpretation involving rapid early development of the subaerial fan and submerged delta terraces of Fox Island River. Sediment derived from the river and from coastal erosion along the front of the fan has been transported southward under net longshore drift to sinks in the vicinity of Two Guts Pond. The submerged delta ten-aces and erosional shore platforms in Port au Port Bay and St. George's Bay indicate that the postglacial sea-level minimum in this area was approximately 25 m below present. These features are undated but their age is estimated to be about 9.5 ± 1 ka. RÉSUMÉ Des levés géophysiques marins ...
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