Ice Contact Deposition example essay topic

Stop 2: Glacial Lake Peterborough Glacial Lake Peterborough had many attributing spillways attached to it, feeding meltwater and sediment from the ice margin and or other glacial lakes. Much of the sediment that was deposited in Glacial Lake Peterborough came from either from the stagnant ice blocks located on the Oak Ridges moraine or from the Lake Algonquin drainage system. Much of the deposition in this lake was dominated by sediment stratification, which may have been largely influenced by thermal stratification. As a result of thermal stratification occurring in this glacial lake sediment inputs were greatly influenced depending on the different sediment densities between the lake bottom water to that of the incoming meltwater and if the inflow density was less / more than the bottom water than the lake water bottom, than new transport and depositional paths were created Depending on the type of path that was created, it would largely influence the rate and distance to which the sediment was transported.

Stop 3 a: Kettleby Till The Kettleby till is considered to be younger than the main till in the area because it may have been deposited by ice contact stratified drift. Ice contact stratified drift is normally deposited by meltwater in contact and or in close proximity to the ice sheet. Stratification and some sorting do takes place. Stop 3 B: Bethany Hills Deltaic sands on southern Flank Yes this feature is the result of erosion and depositional processes however, it is not associated with the current water course.

This feature may be the result of a Gilbert type delta that once occupied this area. Gilbert type deltas have three main components; top sets, forests and bottom sets. Top sets are fluvial sediments (primarily san dur deposits) that were deposited on the sub aerial delta surface. Erosive events occurring on the upper for slope can result in down slope channels and chutes. These features are then eroded by either strong currents or by debris flow resulting in these channels and chutes to become filled. Forests are a combination of sand and gravel facies.

The are deposited by gravitational processes on the delta fore slope and the grains tend to become finer and more angular down slope. Bottom sets consist of fine grained silts and clay and are deposited at the foot of the delta front. Stop 3 C: Drumlin in older northern / Newmarket Till believe that this drumlin is closely related to erosion and accretion hypotheses of drumlin formation. This is because of its location being close to a steep valley wall. The mega flood hypothesis does not apply to this drumlin because this landform has to be in close proximity to the ice sheet margin during periods of glaciation.

Stop 3 E: Lacustrine nearshore / beach deposits on drum line flankGlaciolacustrine beach / near shore sand deposits may have developed at this high elevation as a result of subglacial meltwater experiencing high internal pressures. Another possibility that may have caused deposits to be at this high elevation may be the result of ice either moving over or creating landforms. During this process there is a possibility supra glacial ice may weaken enough that lacustrine deposition may occur at this margin. Stop 3 F: Late Glacial stream erosion in flank of Bethany Hills delta tic sequence It is possible that this feature formed during the final ice retreat, as the ice was melting large volumes of meltwater eroded sediment away from the valley wall due to the high velocity of the stream. Stop 3 G: Late Glacial Fan deposits on flank of Bethany Hills Late glacial fan deposits occur as a result of ice retreating from a drainage basin. When the ice retreated from an area, the landscape experienced rapid readjustment back to the non-glacial conditions.

As a result of this retreat, the sediments within the drainage basin became unstable therefore allowing the sediments to become available to the rivers for transport. Due to this transport, it created valley fills and alluvial fans at the months of tributary valleys or gullies. It is believed that this fan deposit was created during the early stages of de glaciation when the slopes are dominated by debris flow. Stop 3 H: Omemee Esker Dufferin Aggregates Bethany PitEskers in this area were formed as a result of hyper concentrated floodwaters flowing from constricted to expanded reaches and as a result were transformed from a super critical to a subcritical state.

Stop 4: Northern Extension of Omemee Esker During the formation of this esker water flow was controlled by the ice surface and to a smaller extent the form of the bed. This is because water flow is in pressurized conduits. As a result this esker was able to develop long narrow profiles. This type of esker is known as valley esker's. Stop 5: Kame Deposit at Omemee It may be possible that these two landforms were both created by either supra glacial or ice contact deposition. It is possible that both these landforms were created when large quantities of debris was reworked by the supra glacial and englacial drainage systems during the final retreat of glacial ice.

Stop 6: Cheong Lake at Fowlwers Corners The Kawartha Lakes played an important role in the development of the Oak Ridges Moraine. When the ice sheet was advancing southward, the ice sheet was able to erode large amounts of bedrock material from Kawartha area. As a result of this process, large quantities of material accumulated within the ice mass and were transported along until the ice started to retreat. When the ice started to retreat, the sediment that was being carried within the ice mass was deposited. Due to this deposition, the Oak Ridges Moraine was created.