Answer: This is MECHANICAL type of weathering.
Explanation:
Weathering is defined as the process by which rocks breakdown into smaller quantities due to different atmospheric and biological activities.
There are different types of weathering which include:
--> MECHANICAL WEATHERING: This type of weathering is also called physical weathering. Here, rocks are being broken down into smaller pieces but the mineral composition of the rock remains the same. This type of weathering can occur in two ways:
• By Ice wedging: this is one of the easiest ways rocks can be broken into smaller pieces. It occurs at the earth polar regions (climate that regularly cycles above and below the freezing point) and in areas of higher elevations such as the mountains. Ice wedging of rocks occurs when water seeps into cracks, it freezes and expands. This results in wedging (splitting) the rocks apart with repeated freezing.
• By Abrasion: this is another form in which mechanical weathering occurs. Abrasion occurs when strong winds carrying pieces of sand sandblast mountain surfaces. Also moving water, gravity, biological activities can cause abrasion of rock surfaces leading to its weathering.
Therefore, small pieces of sand hitting the side of a mountain and weathering the rock is an example of mechanical weathering by abrasion.