Choose the statement that correctly compares physical weathering to chemical weathering

The correct statement that compares physical weathering to chemical weathering is:

**Chemical weathering forms new substances while physical weathering does not.**

Physical Weathering Chemical Weathering

oxidation
frost wedging
exfoliation
carbonation
oxidation
frost wedging
exfoliation
carbonation

It looks like you're listing processes related to physical and chemical weathering. Here's a breakdown of each process you've mentioned:

**Physical Weathering:**
1. **Frost Wedging:** This occurs when water seeps into cracks in rocks, freezes, and expands, eventually causing the rock to break apart.
2. **Exfoliation:** This process involves the peeling away of layers from the surface of rocks, often caused by temperature changes and the reduction of pressure on the rock.

**Chemical Weathering:**
1. **Oxidation:** This is a chemical reaction that occurs when oxygen reacts with minerals in the rock, often affecting iron-bearing minerals and leading to rust formation.
2. **Carbonation:** This process involves the reaction of carbon dioxide with water to form carbonic acid, which then reacts with minerals in the rock, particularly limestone, leading to the dissolution of the rock.

To avoid repetition, note that "oxidation," "frost wedging," "exfoliation," and "carbonation" each belong to only one category of weathering:

- Physical Weathering: Frost Wedging, Exfoliation
- Chemical Weathering: Oxidation, Carbonation

If you have further questions or need more information, feel free to ask!

Describe how a glacier might erode a valley through the process of abrasion.

Glacial abrasion is a significant process through which a glacier erodes a valley, and it occurs as follows:

1. **Formation of the Glacier:** Glaciers form from the accumulation and compaction of snow over time, creating a large mass of ice. As the glacier moves, it drags along the materials embedded within it.

2. **Incorporation of Sediment:** As a glacier advances, it picks up a variety of sediments, including rocks, gravel, and smaller particles, from the valley floor and sides. These materials become embedded in the base and sides of the glacier.

3. **Movement of the Glacier:** As the glacier flows downhill under the influence of gravity, it carries the embedded sediments with it. The movement of the glacier is typically slow but relentless.

4. **Abrasion Process:** As the glacier moves, the rocks and sediments embedded in its base act like a powerful tool against the bedrock beneath. The pressure exerted by the weight of the glacier enhances the effect of the embedded rocks as they scrape and grind against the valley floor and walls.

5. **Erosion of the Valley:** This abrasive action results in the wearing away of the rock surface, smoothing and polishing it over time. The valley floor becomes wider and deeper, forming a characteristic U-shaped profile that is typical of glaciated valleys. The process also contributes to the creation of features such as striations (grooves carved into the rock by the moving sediment) and glacial polish (a smooth, shiny surface left on bedrock).

6. **Effects Over Time:** Over thousands of years, the continuous process of abrasion greatly modifies the landscape, contributing to the overall shape and morphology of the glacial valley. The sediment that is eroded can also be deposited downstream, forming features such as moraines, outwash plains, and other glacial landforms.

In summary, glacial abrasion is a process where the movement of glaciers, combined with the sediment they carry, erodes the underlying bedrock of a valley, leading to significant landscape changes over geological time scales.