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The difference in chemical weathering time can span millions of years. For example, quickest to weather of the common igneous minerals is apatite, which reaches complete weathering in an average of 10 5.48 years, and slowest to weather is quartz, which weathers fully in 10 8.59 years. [5]
Environmental changes: Changes in pH, temperature, and salt concentration can cause a soil to approach its preconsolidation pressure. [4] [9] Chemical weathering: Different types of chemical weathering will cause preconsolidation pressure. Precipitation, cementing agents, and ion exchange are a few examples.
Two types of physical breakdown are freeze-thaw weathering and thermal fracturing. Pressure release can also cause weathering without temperature change. It is usually much less important than chemical weathering, but can be significant in subarctic or alpine environments. [5] Furthermore, chemical and physical weathering often go hand in hand.
Metasomatism (from the Greek μετά metá "change" and σῶμα sôma "body") is the chemical alteration of a rock by hydrothermal and other fluids. [1] It is traditionally defined as metamorphism which involves a change in the chemical composition, excluding volatile components. [2]
Representative bulk densities of soils. The percentage pore space was calculated using 2.7 g/cm 3 for particle density except for the peat soil, which is estimated. [43] Soil treatment and identification Bulk density (g/cm 3) Pore space (%) Tilled surface soil of a cotton field 1.3: 51 Trafficked inter-rows where wheels passed surface 1.67: 37
[3] [4] Quartz is the most common mineral in the sand or silt fraction as it is resistant to chemical weathering, except under hot climate; [5] other common minerals are feldspars, micas and ferromagnesian minerals such as pyroxenes, amphiboles and olivines, which are dissolved or transformed in clay under the combined influence of physico ...
Case hardening is a weathering phenomenon of rock surface induration.It is observed commonly in: felsic alkaline rocks, such as nepheline syenite, phonolite and trachyte; pyroclastic rocks, as pyroclastic flow deposit, fine air-fall deposits and vent-filling pyroclastic deposits; sedimentary rocks, as sandstone and mudstone.
A discontinuity may exist as a single feature (e.g. fault, isolated joint or fracture) and in some circumstances, a discontinuity is treated as a single discontinuity although it belongs to a discontinuity set, in particular if the spacing is very wide compared to the size of the engineering application or to the size of the geotechnical unit.