Which is the last stage of physical weathering rocks?
A. Rock
B. Boulder
C. Sand
D. Pebble
C. Sand
The correct answer is B. Boulder.
The last stage of physical weathering rocks is typically the formation of small fragments or particles. Among the given options, the choice that represents small fragments is pebble (option D).
Physical weathering is the breakdown of rocks into smaller pieces without altering their chemical composition. It occurs through various processes like frost wedging, thermal expansion and contraction, abrasion, and biological activity. Over time, these processes lead to the gradual disintegration of rocks into smaller pieces.
To understand this concept, you can observe the following steps:
1. Start by learning about the different processes involved in physical weathering, such as frost wedging, which occurs when water seeps into cracks or pores in rocks, freezes, and expands, causing the rock to break apart.
2. Explore additional physical weathering mechanisms like thermal expansion and contraction, where rocks are exposed to extreme temperature changes that cause them to expand and contract, resulting in cracks and fractures.
3. Discover how abrasion contributes to physical weathering by the grinding, rubbing, or scraping of rocks against each other or external forces like wind or water, wearing them down into smaller particles.
4. Understand biological weathering, which involves living organisms like plants or burrowing animals that exert pressure on rocks, leading to the breakdown of the rock material.
5. Finally, identify the various stages or sizes of final products in physical weathering, ranging from large rocks or boulders to smaller fragments like pebbles and ultimately sand.
By following these steps, you can better understand the last stage of physical weathering, which is the formation of pebbles (option D) from larger rocks or boulders.