Metamorphic rocks start from the changing in the texture and mineral whole of sedimentary, igneous, and older metamorphic rocks under excessive pressure and heat within the earth. Some of the most common metamorphic rocks are gneiss, quartzite, schist, slate, and marble. (2) There are tons of examples of how a type of sand tells of the land it is from because of the rocks it is made up of. A great example of that is if you find sand made from plutonic igneous rocks, then one know that the sand is probably near mountains, since plutonic igneous rocks form the bulk of mountain ranges. (6) Sand made of volcanic rocks, which is probably extrusive rock (2), are most likely near volcanoes because those rocks are formed from lava.
The seawater combined with the limestone produces a weak chemical solution, which erodes the base of the cliff and produces a pitted effect. Chemical Weathering is when water weakens the structure of the rock and Mechanical Weathering is where water seeps into the rock face causing fragments of rock to break off. These types of erosion have caused the formation of several phenomena at Muriwai. Motutara Island (stack) was produced by the formation of two caves on either side of the headland -- forming an arch and the roof slowly erodin... ... middle of paper ... ...ll build up the dunes and travel inland. Surface Creep occurs when landing sand particles remove the larger and heavier particles, pushing them forward.
When the plants use the water, the salt context is left behind within the soil which accumulates over time, this process is known as salinisation. Especially saline soils are often recognised by a white layer of salt on the surface of the soil. As the soil becomes waterlogged (refers to the saturated soil), vegetation and crops die since they have a constrained access to oxygen. Excessive salt within the root zone reduces plant growth due to increasing energy that the plant must expend to acquire water from the soil (NSW Environment, 2013) (Department of Primary Industries,
It shows that when the loosely packed sand is disturbed very slowly, the natural arrangement of particles will be disordered, reducing the volume. As shown in figure, if this sand layer is located below the groundwater level and pore water flows between sand grains, then ... ... middle of paper ... ...verburden pressure increases. Cyclic Loading The level of pore-pressure excess required to initiate liquefaction is related to the amplitude and duration of earthquake-induced cyclic loading. The amount of damage to structures on soils undergoing liquefaction depends on how long the sand remains in a liquefied state. Seed (1976) concluded that the multidirectional shaking is more severe than one-directional loading in terms of pore pressure.
Chemical weathering changes the materials in soil or rock. One example is when carbonic acid, which is made when carbon dioxide mixes with water, dissolves rock. This is especially effective when dissolving limestone. Another example is when a rock with iron rusts and expands, which breaks the rock. Chemical weathering can cause holes, sinkholes, and caves to form in rocks.
THEORY 2.1 EXPANSIVE SOILS Soils which expand when water is added and which shrink when they dry out are called expansive soils. This continuous change in soil volume causes the structures built on this soil to move unevenly and crack. Expansive soils pose a significant hazard to foundations especially for light buildings. The characteristics of expansive soils are due to the presence of swelling clay minerals. As they get wet, the clay minerals absorb water molecules and expand; conversely, as they dry they shrink, resulting in large voids in the soil.
In other word, the soils still remain on the rock where it is originally formed. The residues left are due to weathering process and transportation, which contain insoluble products of rock weathering. Chemical composition of residual soils is the same as the parent rocks which rich in humus. Besides that, landslides and soil erosions occur due to rainfall is commonly happened in residual soils area (Rahardjo et al., 2005). Arthur (2010) pointed out that landslides and soil erosions occur because residual soils crumble easily and break down rapidly.
It was observed that the strength behaviour of lateritic soils is very dependent on the moisture content due to samples tested (Baldovin, 1969). It was also observed that due to a decrease in moisture content, there was an increase in cohesion and internal friction angle of the soil (Paulson, 1975). This character is associated to the variation in soil structure with varying moisture content, such that, as the soil dries out part of the hydrated colloidal iron and aluminum oxides dehydrates and forms strong bonds among certain soil grains which then causes an increase in
The beach is also the main source for dunes to be formed. 29. Scarp and the railing of the walkway are examples of erosion and deposition, and scarp is formed during the erosion process due to the storms. Dune deposition cause the dunes to migrate onto the walkways, which cover parts of the walkways, and allow less space for human to pass by. 30.
A process called buffering is used to neutralize acids using the base nutrients (including calcium and magnesium) found in soil (Tyson, 1992). This process helps soil resist the effects of acid rain. Thinner soils that have fewer nutrients are more vulnerable to the effects of acid rain. Thicker soils are more affective at buffering acid rain. Over many years soils that aren’t the best at buffering out acid rain can become increasingly acidic.