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Lab 2 Landforms - Ground Moraines - Shallow Drift Overlying Bedrock - End Moraine - Lacustrine Deposits - Alluvial Deposits - Organic Deposits Soil moisture often fresh to moist Wet soil moisture Ground Moraine (Subglacial Till) General Description ã Ground moraine is typically an undulating till plain that is often grooved, fluted or drumlinized parallel to the direction of ice flow. ã During the ice advance, the debris composed of soil and rock fragments was accumulated in the basal layer
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  Landforms -Ground Moraines-Shallow Drift Overlying Bedrock-End Moraine-LacustrineDeposits-Alluvial Deposits-Organic DepositsSoil moisture often fresh to moistWet soil moisture Lab 2  Ground Moraine (Subglacial Till) General Description ã  Ground moraine is typically an undulating till plain that is often grooved, fluted or drumlinizedparallel to the direction of ice flow. ã During the ice advance, the debris composed of soil and rock fragments was accumulated in the basal layer of the glaciers and, due to frictional drag and melting, deposited directly beneath the ice as subglacial till . ã Individual fragments within the tills are often also laid out in the direction of ice flow. ã They are flat to gently undulating, usually without abrupt or steep slopes. ã Ground moraines exhibit a variation in thickness but tend to be thinner on bedrock knolls and ridges and deeper in depressionalsite positions. ã Since it was compressed by the ice sheet, the till is often compact and impervious. ã It contains rock fragments that reflect the characteristics of local bedrock conditions.  Occurrence ã Ground moraines are extremely common in NW Ontario. ã Together with the configuration of underlying bedrock, spatial patterns of ground moraines are responsible for most of the landform of NW Ontario. ã Till deposits that are sufficiently thick to mask the expression of bedrock topography are found along the northern border of the Precambrian (Canadian) shield. ã Ground moraines associated with drumlin fields occur to the west of Geraldton, in the Red Lake-Savant Lake-Pickle Lake area and to the southwest of Lake Nipigon. ã In S. Ontario, because of their flat or gently-rolling terrain, ground moraines are often cultivated for large farms.Ground Moraine (Subglacial Till) General Description (cont’d) ã Drainage patterns are mostly disordered and random. In S. Ontario, dendritic drainage patterns also occur. ã Present are many small, undrained, irregularly-shaped depressions.  Common Properties ã Minimal suitability of the moraine deposits for the aggregate extraction because of them being unsorted, unstratified, with considerable spatial variability in thickness and composition. In S. Ontario, the material is well graded (sand, silt, clay). ã Presence of shallow soils and high boulder content can make construction of buildings and roads on moraines very difficult and may restrict tree harvesting. ã Depressional sites on compacted soils often have high water tables and are covered with organic materials. ã Upper slope positions on shallow soils can have dry moisture conditions due to excessive draining.
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