The question asks to identify the region where frost shattering (gelifraction) is the dominant weathering process. Frost shattering is a type of physical weathering that requires specific climatic conditions, primarily the repeated freezing and thawing of water.
D) Periglacial and alpine regions are characterized by frequent temperature fluctuations around the freezing point and the presence of water (from snowmelt or rain), which are the essential conditions for frost shattering to occur effectively and dominantly.
The question describes a specific type of physical weathering where rock slabs are broken apart by the growth of salt crystals within cracks and crevices. We need to identify the correct term for this process from the given options.
C) Salt weathering (haloclasty) — This term specifically refers to the physical disintegration of rocks due to the growth of salt crystals in cracks and pores. As water evaporates, dissolved salts crystallize, and the growing crystals exert pressure on the rock, causing it to break apart. Haloclasty is the scientific name for this process.
The question asks to identify the geological process where rocks expand and fracture parallel to the surface due to unloading or pressure release. We need to evaluate each option based on its definition and mechanism of rock weathering.
D) Sheeting or pressure release jointing — This term accurately describes the process where the removal of overlying material (unloading) reduces the confining pressure on the underlying rock. The rock then expands, leading to the formation of fractures or joints that are roughly parallel to the land surface. This can result in the peeling off of concentric layers, a form of exfoliation.
The question asks about the process leading to the block disintegration of granite into angular blocks. This phenomenon is a type of physical weathering. We need to identify the weathering process that specifically causes granite to break into angular blocks, often exploiting pre-existing weaknesses.
B) Exploitation of existing joints and fractures by weathering agents. This is the primary mechanism by which granite, a jointed rock, breaks down into angular blocks due to physical weathering processes like frost action, thermal expansion/contraction, or pressure release.
The question asks about granular disintegration, a type of physical weathering. We need to identify the rock type and environmental conditions most susceptible to this process.
C) Coarse-grained igneous rocks like granite in arid regions. This option perfectly matches the conditions required for granular disintegration: coarse-grained rocks with multiple minerals and extreme diurnal temperature variations.
The question asks to identify which option is NOT a type of physical/mechanical weathering. We need to understand the difference between physical/mechanical weathering and chemical weathering.
Hydrolysis is a chemical weathering process where water reacts with minerals in rocks, breaking them down and forming new minerals. For example, feldspar minerals react with water to form clay minerals. This involves a change in chemical composition, thus it is not a physical/mechanical weathering process.