Exposure to water
Weathering Process The weathering process occurs when rocks are exposed to the hydrosphere (water) and atmosphere (air). These weathering agents can change the physical and chemical characteristics of rocks. Physical Weathering Physical weathering occurs when rocks are broken in to smaller pieces without changing the chemical composition of the rock. Think of a physical change (e.g., ripping a piece of paper) where the sample will change in size but all its other characteristics will remain the same. Spheroidal weathering is a form of chemical weathering that affects jointed bedrock and results in the formation of concentric or spherical layers of highly decayed rock within weathered bedrock that is known as saprolite. Spheroidal weathering is the result of chemical weathering of systematically jointed, massive rocks, including granite, dolerite, basalt and sedimentary rocks such as silicified sandstone. It occurs as the result of the chemical alteration of such rocks along intersecting joints. Physical weathering is also known as mechanical weathering. This type of weathering occurs when rocks and other landforms are broken down by physical factors in the environment. These physical factors include wind, water, sun, ice and temperature changes. This type of weathering does not change the chemical composition of the rock or minerals. Weathering is different from erosion. Erosion is the movement of rock pieces and sediment from one area to another. Weathering is the breaking down of rocks and erosion is a wearing away of rocks. There are two main types of weathering: physical (or mechanical) weathering and chem There are three basic types of chemical reactions that cause four types of chemical weathering of rocks. Dissolution and hydrolysis are caused by reactions with acids. Hydration is the absorption of water. Oxidation is reaction with oxygen. 1.  Weathering is the chemical and physical processes that change the characteristics of rocks on the Earth s surface. It is also known as the preparation for erosion. In order for weathering to occur, the environment of a rock sample must change and the rock needs to be exposed to some form of water and the air. Physical Weathering Physical weathering occurs when rocks are broken in to smaller pieces without changing the chemical composition of the rock. Think of a physical change (e.g., ripping a piece of paper) where the sample will change in size but all its other characteristics will remain the same. (a) Chemical Weathering results from chemical reactions between minerals in rocks and external agents like air or water. Oxygen oxidizes minerals to alteration products whereas water can convert minerals to clays or dissolve minerals completely.  Chemical Weathering. Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic. These chemical processes need water, and occur more rapidly at higher temperature, so warm, damp climates are best. Chemical weathering (especially hydrolysis and oxidation) is the first stage in the production of soils. Chemical weathering can also result from exposure to water. Hydrolysis occurs when silicate minerals react with water so that the mineral recombines with the water molecule to form a new mineral. For example, consider the mineral potassium feldspar. Chemical weathering refers to the processes by which rocks react with the atmosphere to form new substances. These reactions can alter a rock and transform the rock into sand, clays, and other minerals. CHEMICAL WEATHERING. Like mechanical weathering, there are several different types of chemical weathering
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chemical weathering occurs as a result of the