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Many explanations have been proposed for honeycomb and other cavernous weathering. These explanations include marine abrasion; wind corrosion; mechanical weathering resulting from short-term temperature variations; chemical weathering of the interior of the rock (core-softening) under a protective crust (case-hardening) followed by mechanical removal of the softened material; biogeochemical ...
The materials left after the rock breaks down combine with organic material to create soil. Many of Earth's landforms and landscapes are the result of weathering, erosion and redeposition. Weathering is a crucial part of the rock cycle; sedimentary rock, the product of weathered rock, covers 66% of the Earth's continents and much of the ocean ...
The mudcracked rock is then later exposed to erosion. [2] In these cases, the original mud cracks will erode faster than the newer material that fills the spaces. This type of mudcrack is used by geologists to determine the vertical orientation of rock samples that have been altered through folding or faulting .
An essential feature for the formation of laterite is the repetition of wet and dry seasons. [15] Rocks are leached by percolating rain water during the wet season; the resulting solution containing the leached ions is brought to the surface by capillary action during the dry season. [15]
Neolithic Subpluvial/African humid period in North Africa, wet 7000–3000: Holocene climatic optimum, or Atlantic in northern Europe (B-S) 6200: 8.2-kiloyear event cold 5000–4100: Older Peron warm and wet, global sea levels were 2.5 to 4 meters (8 to 13 feet) higher than the twentieth-century average 3900: 5.9 kiloyear event dry and cold. 3500
The carbonate-silicate cycle is the primary control on carbon dioxide levels over long timescales. [3] It can be seen as a branch of the carbon cycle, which also includes the organic carbon cycle, in which biological processes convert carbon dioxide and water into organic matter and oxygen via photosynthesis. [5]
Cyclic sediments (also called rhythmic sediments [1]) are sequences of sedimentary rocks that are characterised by repetitive patterns of different rock types or facies within the sequence. Processes that generate sedimentary cyclicity can be either autocyclic or allocyclic, and can result in piles of sedimentary cycles hundreds or even ...
For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when xenoliths are found. These foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in the matrix. As a result, xenoliths are older ...