Abstracts

and quantity perspectives. This work has resulted in a clearer picture of the sediment records
contained within the valley and its tributaries. No single continuous aquifer exists
across the entire valley length, but rather, each thalweg appears to contain aquifer segments
of varied connectivity. These deeply buried aquifers are typically confined by compact tills
and very fine-textured glaciolacustrine deposits. The final product of this study is an updated
conceptual three-dimensional geologic model for the Dundas buried bedrock valley
system that highlights potential aquifer units to be targeted for future investigation.
195 - Stratigraphic record and deglacial history of the interlobate
zone between Ingersoll and Cambridge, southwestern Ontario,
Canada
Andy F. Bajc
Ontario Geological Survey, Sudbury, Ontario, Canada
Stratigraphic modelling of Quaternary sediments along the interlobate zone of southwestern
Ontario (Ingersoll-Cambridge) was undertaken as part of the Ontario Geological
Survey’s groundwater initiative. The objective of the initiative is to develop interactive 3-D
models of Quaternary geology that provide geologic frameworks for groundwater studies.
The framework was developed by reviewing and compiling archival surficial and subsurface
geologic information and by continuously coring 44 boreholes to bedrock.
A regionally consistent and reproducible stratigraphic succession was encountered comprising
an older drift package on bedrock of Early Wisconsin or Illinoian age consisting
of Erie-lobe diamicton (Canning Till) and associated stratified deposits. Discontinuous,
non-glacial, organic-rich stratified deposits indicating cool, interstadial conditions unconformably
overlie the older drift package and suggest a period of ice withdrawal spanning
the interval 23.5 to >50 ka BP. Nissouri Phase Catfish Creek Till unconformably overlies
these deposits and compositionally displays a shift in provenance from early, lobate ice flow
to more regional, southerly flow followed by late, lobate ice flow in response to a thinning
ice sheet. Catfish Creek Till is a distinctive marker horizon in southern Ontario that commonly
acts as a regional aquitard. An interlobate zone following the Highway 401 corridor
represents the suture line along which the Erie-Ontario and Huron ice lobes separated
following the Nissouri Phase. Stratified deposits of the Waterloo moraine accumulated
along the interlobate zone in either a subglacial or ice-walled lake. Correlative deposits
accumulated to the southwest in the Woodstock, Dorchester and Lakeview moraines.
Progressive retreat of the Erie-Ontario and Huron ice lobes resulted in the catastrophic
drainage of these lakes along either ice-marginal or subglacially-carved tunnel channels
occupying the modern courses of the Thames and Middle Thames rivers and Trout Creek.
A period of ice recession resulted in the widespread deposition of fine-medium textured
glaciolacustrine deposits on the Erie-Ontario side of the interlobate zone with limited
accumulation on the Huron side. Slight readjustments in the overall retreat of the Huron
and Erie-Ontario ice lobes resulted in the deposition of Tavistock Till and Port Stanley
and Wentworth tills, respectively. A series of well-developed recessional and/or terminal
moraines were constructed along the retreating Erie-Ontario ice lobe resulting in the local
178 IAH-CNC 2015 WATERLOO CONFERENCE