Abstracts

accumulation of thick sequences of subaquatic fan sediments capped by variably textured
diamictons. Downcutting and subsequent backfilling of low-lying areas between the moraines
with deltaic deposits of the Norfolk sand plain resulted in the local removal of Port
Stanley and Wentworth till.
270 - Sedimentology and Hydrogeology of the Paris and Galt
Moraines
H.E.J. Russell & D.R. Sharpe
Geological Survey of Canada, Ottawa, Ontario, Canada
A.F. Bajc
Ontario Geological Survey, Ministry of Northern Development and Mines, Sudbury,
Ontario, Canada
D.I. Cummings
Department of Earth Sciences, Carleton University, Ottawa, Ontario, Canada
The Paris and Galt moraines extend from near Lake Erie, 130 km north towards the
Caledon area, are up to 11 km wide, and have a relief of 30 m. They evolve from two distinct
ridges in the south to a broad, hummocky terrain with multiple ridges and secondary
landscape elements (kettle depressions, eskers, subaerial fans, channels) in the north. These
geomorphic changes are mirrored by changes in sediment type, thickness, and stratigraphy.
Continuous cores reveal that the moraine consists of a succession of intercalated sand,
gravel and diamicton units. Depending on the geographic location, a variety of different
units can underlie the moraine, including older tills, lacustrine mud, or glacifluvial sand
and gravel. Locally, the lower contact is cryptic where the moraine overlies sedimentologically
similar deposits. Outcrop data suggest northern and southern parts of the moraine are
different. Within the southern glacilacustrine basin, large foresets of >10 m height occur at
the base of one pit exposure. By contrast, horizontally stratified outwash gravel is common
in northern pits. A stoney, sandy silt diamicton, (Wentworth Till), covers large parts of the
moraine, is massive to stratified, and is locally inter-bedded with sand and gravel. Where
overlain by gravel, its upper contact can be loaded, suggesting it was water-saturated and
thus prone to deformation during gravel deposition. Glacifluvial deposits are present in
front of and locally underneath the moraine. The moraine strata are interpreted to have
been deposited during a pause in the overall retreat of the Erie-Ontario ice margin with a
highly variable meltwater flux both spatially and temporally. The narrow, southern moraine
ridges may represent more rapid retreat within a glacial lake basin given the scale of foresets
and confining lacustrine sediment. The northern, broader hummocky terrain is interpreted
to have been deposited in a terrestrial environment based on the bedding character of the
glacifluvial sand and gravel.
Of the numerous moraines present within the Grand River watershed, the Paris-Galt moraines
represent one of the three most hydrogeologicaly significant moraines, along with
the Waterloo and Orangeville. The hummocky terrain of the moraine likely contributes
to enhanced infiltration and recharge; a number of local aquifers occur within the moraine
sediments (e.g. St George Aquifer); and the porous substrate of the moraine enhances
groundwater contribution to baseflow of the Grand River.
IAH-CNC 2015 WATERLOO CONFERENCE
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