A new late-glacial sea-level record for St. George's Bay, Newfoundland

A new relative sea-level curve is presented for St. George's Bay, southwest Newfoundland, based on (i) a revised stratigraphic framework and depositional model for glacial and marine deposits exposed in coastal sections and (ii) 19 new radiocarbon dates on shells from emerged and submerged marine deposits, including fossiliferous diamictons. The data produce a type B sea-level curve, falling steeply from an extrapolated marine limit of 105 m above sea level at 14.0 (super 14) C ka BP, passing below modern sea level at approximately 10.6 (super 14) C ka BP, to a lowstand of -25 m at approximately 9.4 (super 14) C ka BP, and rising again close to modern sea level by 5.0 (super 14) C ka BP. Marine limits in the northern part of the bay have lower elevations (27-65 m) due to delayed ice retreat of up to 1.2 ka. Between 12.8 and at least 12.3 (super 14) C ka BP, glaciofluvial outwash graded to falling sea levels between 27 and 17 m above present throughout the bay, whereas lowstand deltas were constructed in sheltered locations at the outlets of major river systems, when sea level was 25 m below present. Establishment of the sea-level lowstand at approximately 9.4 (super 14) C ka BP is supported by new seismic data and radiocarbon dates from St. George's Bay and also from White Bear Bay on the south coast of Newfoundland. Short-term fluctuations in emergence rates of 1-2 m/century between 12.5 and 9.5 (super 14) C ka BP are attributed to variable eustatic sea-level rise, superimposed on a declining local glacio-isostatic adjustment.