Ice is an important agent of weathering.
Weathering is the natural process by which rocks are broken down into smaller pieces. This is an important process because it eventually leads to the development of functioning ecosystems; life would not exist if not for the process of weathering. Ice is one of several different agents of weathering. Does this Spark an idea?
Categories of Weathering
There are two different categories of weathering. Mechanical weathering, also referred to as physical weathering, occurs when a rock is physically broken down without changing its chemical composition. Chemical weathering occurs when a rock is broken down by a chemical process that alters the rock’s chemical composition. Chemical and mechanical weathering are complementary processes. Ice is a factor in two different forms of mechanical weathering: glaciation and frost wedging.
Glaciation is a form of mechanical weathering caused by glaciers. Glaciers are large masses of ice that slowly move over time. As they move, glaciers carve deep valleys into bedrock, breaking it apart and carrying pieces of it away. Glaciers are, therefore, an agent of erosion as well as an agent of mechanical weathering. In the form of glaciers, ice not only breaks down rock, but quite literally shapes the surface of the Earth.
The other form of mechanical weathering that involves ice is referred to as “frost wedging.” Frost wedging occurs when water seeps into a crack or pore in a rock. If that water freezes, it will expand, creating pressure in the crack and widening it until the rock fractures. This type of weathering depends on temperature changes to occur and can be a major problem for people in colder climates because of the potentially destructive effects that it has on roads and buildings.
Salt Crystallization and Ice Wedging
Another form of mechanical weathering is known as “salt crystallization.” Much like frost wedging, salt crystallization occurs when a saline solution enters a crack or pore in a rock and then crystallizes due because of a temperature change, eventually fracturing the rock. Salt crystallization can occur on its own, and it can also occur in tandem with frost wedging. According to Michael Pidwirny, associate professor of physical geography at the University of British Columbia Okanagan, the effects of frost wedging are increased by the presence of salt.
By breaking apart rock into smaller and smaller pieces, the processes of glaciation and frost wedging help to form soil. This is incredibly important because soil is necessary for plants to live and function. Weathering allows plants to access the minerals and nutrients in rock by breaking it down into tiny, manageable pieces. In this way, glaciation and frost wedging help ecosystems form and make life on earth possible.