what kind of terrain and landforms would indicate the prior existence of a continental glacier
To determine the prior existence of a continental glacier, you should look for specific terrain features and landforms. Here are some indicators:
1. U-shaped Valleys: Look for valleys with a wide, U-shaped cross-section rather than the V-shaped ones formed by rivers. These U-shaped valleys are a result of the erosive power of a continental glacier as it moves and carves through the landscape.
2. Moraines: Moraines are accumulations of debris, such as rocks and sediment, carried and deposited by a glacier. There are different types of moraines:
- Lateral Moraines: Found along the sides of the valley, created when the glacier erodes and carries debris along its edges.
- Medial Moraines: Formed when two glaciers with lateral moraines merge, and the debris from both sides merge in the middle of the combined glacier.
- Ground Moraines: Consist of a mixture of rocks and sediment that was deposited beneath the glacier.
- Terminal Moraines: Created when a glacier reaches its furthest extent and deposits a crescent-shaped ridge of debris.
3. Glacial Erratics: These are large boulders that were transported by glaciers and deposited in areas with different rock types. They are typically different from the surrounding landscape, and their presence indicates the past existence of a glacier.
4. Drumlin Fields: Drumlins are elongated hills with a smooth, streamlined shape, typically aligned in the direction of ice flow. They are formed when a glacier deposits sediment and reshapes the land beneath it.
5. Eskers: Eskers are long, winding ridges of gravel and sand. They are created when meltwater drains through, underneath, or along the end of a glacier, depositing the material it carries in a sinuous pattern.
6. Kettle Lakes: These are depressions in the landscape formed when blocks of ice become detached from a retreating glacier and are then buried in sediment. When the ice melts, it leaves behind a hollow that fills with water, creating a kettle lake.
By observing and identifying these specific terrain features and landforms, you can gather evidence of the presence of a prior continental glacier.
The presence of certain terrain and landforms can indicate the prior existence of a continental glacier. Here are some key features to look for:
1. Striations and grooves: Glaciers can leave behind long, parallel striations and grooves in rocks and bedrock surfaces. These marks are created by the movement of rocks embedded in the base of the glacier.
2. U-shaped valleys: Continental glaciers tend to erode valleys into a characteristic U-shape, as opposed to V-shaped valleys created by rivers. U-shaped valleys have steep, straight sides and a flat floor, indicating the presence of a glacier that eroded the valley over time.
3. Moraines: Glacial moraines consist of piles or ridges of rocky debris carried and deposited by the glacier. They can appear as ridges along valley floors or as mounds of material at the snout or sides of a glacier. Terminal moraines are deposited at the furthest extent of the glacier, while lateral moraines form along the sides.
4. Glacial erratics: These are large boulders or rocks that have been transported and deposited by glaciers far from their original source. Erratics often differ in composition from the surrounding rocks and can be found scattered across the landscape.
5. Drumlin fields: Drumlins are oval or elongated hills composed of glacial till (sediment) that were formed under the glacier. They have a steep side facing the direction from which the glacier advanced and a more gentle slope on the opposite side.
6. Eskers: These are long, winding ridges of sand and gravel that were deposited by meltwater streams flowing within or beneath the glacier. Eskers can extend for several kilometers and may curve around hills or depressions in the landscape.
7. Kettles: Kettles are depressions or small lakes formed when a large block of ice gets buried and subsequently melts, leaving behind a hole. These are often found in areas where the glacier's front was stagnant or receding.
These are just a few of the terrain and landform indicators that suggest the prior existence of a continental glacier.