The correct option is (c) 1 and 3 only.
Explanation
Weathering is the process of disintegration and decomposition of rocks and minerals on the Earth's surface. It is an in-situ or on-site process, meaning there is little or no movement of the materials. It acts as a precursor to erosion and is fundamental to the rock cycle and soil formation.
Statement-wise Analysis
- Statement 1 is Correct: Weathering is defined as the mechanical disintegration (breaking up) and chemical decomposition (decay) of rocks through the actions of various elements of weather and climate. It reduces massive rock structures into smaller fragments and sediments.
- Statement 2 is Incorrect: Weathering is not caused only by temperature changes and frost action. It is classified into three main types based on the agents involved:
- Physical (Mechanical) Weathering: Caused by temperature changes, frost action (freeze-thaw cycles), and pressure release.
- Chemical Weathering: Caused by oxidation, carbonation, hydration, and solution.
- Biological Weathering: Caused by the roots of plants, burrowing animals, and human activities.
- Statement 3 is Correct: Weathering is the primary step in pedogenesis (soil formation). The weathering of bedrock (parent material) produces the mineral matrix (regolith) which, when combined with organic matter and subjected to time and biotic activity, evolves into soil.
Key Takeaway
Weathering encompasses physical, chemical, and biological processes that break down rocks in-situ. It is distinct from erosion (which involves transport) and is the essential initial stage in the formation of soil.