GEOLOGY

Detailed explanation-1: -Physical erosion describes the process of rocks changing their physical properties without changing their basic chemical composition. Physical erosion often causes rocks to get smaller or smoother.

Detailed explanation-2: -Weathering is the breaking down or dissolving of rocks and minerals on Earths surface. Once a rock has been broken down, a process called erosion transports the bits of rock and minerals away. Water, acids, salt, plants, animals, and changes in temperature are all agents of weathering and erosion.

Detailed explanation-3: -Mafic silicates like olivine and pyroxene tend to weather much faster than felsic minerals like quartz and feldspar.

Detailed explanation-4: -Mechanical weathering is sometimes called physical weathering, and it describes the process of rocks crumbling. Water is the key agent in mechanical weathering. Temperature changes are also a main agent in mechanical weathering. The main type of mechanical weathering is freeze-thaw weathering.

Detailed explanation-5: -River rocks tend to be smooth and round because of a combination of the geologic processes of erosion and weathering. Rocks are eroded from surrounding areas and are initially rough and jagged, but over many years they are weathered via transport-induced abrasion to become smooth and rounded.