Weathering and erosion
Weathering and erosion - not the same thing!!!
Too often these two terms are used interchangeably, as if they were different words for the same process. But, you know... They aren’t. So let’s clear up this misconception.
Firstly, weathering. This is the term given to the breaking down of rocks into smaller pieces (mechanical weathering) or into simpler chemicals (chemical weathering).
Mechanical weathering can be due to:
Wind - Carries sand and wears away rock.
Water - Rolls rocks in rivers, rounding them. Wave action wears away beachfronts. Water in cracks splits rocks when it freezes and expands.
Glaciers - Moving ice shapes mountain valleys.
Plants - Roots can split rocks.
Temperature - Heating and cooling rocks rapidly can cause splitting.
Chemical weathering can be due to:
Air - Oxygen reacts with minerals.
Water - Reacts with some rocks over a long time.
Acids - Weak acid in normal rain or strong acid in acid rain breaks down rocks, especially limestone.
Erosion, on the other hand, is the movement of weathered rock. This can be by the action of wind, water, glaciers, or gravity. Erosion results in materials being deposited somewhere. The action of gravity and water generally moves materials downwards, and most end up in lakes and seas.
So you see? Two different words for two different processes. First weathering, then erosion.