ABSTRACT: Stratigraphy of Late Quaternary sediments exposed in coastal cliffs, west of Stephenville

CGRG Bibliography of Canadian Geomorphology
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Abstract

Exposures of Quaternary sediment between Stephenville and Port au Port Peninsula were examined to develop a Quaternary stratigraphy for the northern part of St. George's Bay. This area contains the only dated exposure, at Kippens, related to the Robinsons Head readvance, a major component of the late glacial history of western Newfoundland. The western extent of this readvance is marked by exposures near Romaines Brook. Sediment sections were logged at 15 locations along the coast. Exposures, 7 to 35 m high, contained diamicton, mud, sand and silt, sand and gravel, marl, peat and loess. Detailed descriptions of exposures at Kippens and Romaines Brook are presented. Preliminary interpretation suggest that sediment assemblages west of Romaines Brook, particularly between Berry Head and Romaines Brook, were deposited in an ice-proximal glaciomarine environment, along the grounding line of a tidewater glacier. Sediment east of Romaines Brook were deposited as glaciofluvial deltas built by a proglacial outwash system. The interpretation of the sediment at the Kippens section supports a history of initial ice-proximal glaciomarine sedimentation, followed by deltaic progradation produced by glacial retreat in a shallowing sea. Sediment in the Romaines Brook section show a complex depositional sequence of ice-proximal glaciomarine sediments, some of which have collapsed into a depression, and mud showing a transition from a marine to freshwater environment, deposited during postglacial relative sea level fall. Surface geomorphology in the Kippens area that shows numerous near-coast depressions interpreted as kettle holes, supporting an ice-contact environment, may be explained through an origin as gypsum karst sinkholes.

Bibliography of Canadian Geomorphology