Term
|
Definition
Carbonic acid is created when CO2 dissolves in water. Carbonic acid attacks feldspar, augite, biotite, and dissolves out of elements such as K, Na, Mg, and Ca. The compounds that form when the carbonic acid reacts with these elements are called carbonates. Clay can also form. Carbonic acid also dissolves calcite and this hollows out caverns. An example is the Luary caverns. Acids are formed from plants and animals and are then dissolved by rainwater and carried underground. There, they attack minerals. Industry also plays a part. Gases are released by the industry and they mix with the atmosphere and water vapor and this creates acid rain. This is a serious problem since this alters the Ph of the lakes. |
|
|
Term
Chemical Weathering
[image] |
|
Definition
Rainwater, oxygen, carbon dioxide, and plant decay acids are all examples of chemical erosion. These are called agents.
Hydration and Hydrolysis is a chemical reaction of water and other substances. Hydration is when water combines with another substance. An example is the hydration of anhydrite turning into gypsum. The formula is CaSO4 (anhydrite) + 2H2O (water) + CaSO4 times 2H2O (gypsum). Water can also form hydrogen ions (H+) and (OH-). When these ions replace the minerals, the reaction is called Hydrolysis. Minerals such as feldspar, hornblende, and augite combine with water to form clay.
Oxidation is where the atmosphere is 21% oxygen. THe O2 combines with another substance. This is oxidation. It reacts with iron bearing minerals such as magnetite, pyrite, and mafic silicates such as hornblende, augite, and biotite yields rust. When the oxygen combines with the iron, chemical bonds are broken down, weakening the structure. Other elements such as Al, and Si, do the same thing. The red in the hematite is from the oxygen combining with the iron. Water can also produce a blackish color in geothite. If the geothite is dehydrated, it then forms hematite. The color can also indicate with lies underneath. This process can be compared to rusty nails vs. new ones. |
|
|
Term
|
Definition
| Soil creep is a very, very slow form of mass wasting. It's just a slow adjustment of soil and rocks that is so hard to notice unless you can see the effects of the movement. These effects would be things like fenceposts shifted out of alignment, or telephone poles tipping downslope. Another effect is the way a grass covered slope seems to ooze downhill forming little bulges in the soil. This heaving of the soil occurs in regions subjected to freeze-thaw conditions. The freeze lifts particles of soil and rocks and when there is a thaw, the particles are set back down, but not in the same place as before. Gravity always causes the rocks and soil to settle just a little farther downslope than where they started from. This is the slow movement that defines creep. Creep can also be seen in areas that experience a constant alternation of wetting and drying periods which work in the same way as the freeze/thaw. Monitoring is essentially done through observation of the effects of creep. Since the process is so slow, it can only be monitored in terms of flow over long periods of time. |
|
|
Term
|
Definition
| Erosion is the process by which the surface of the Earth gets worn down. Erosion can be caused by natural elements such as wind and glacial ice. But anyone who has ever seen a picture of the Grand Canyon knows that nothing beats the slow steady movement of water when it comes to changing the Earth. The key to erosion is something called "fluid flow." Water, air, and even ice are fluids because they tend to flow from one place to another due to the force of gravity. Of the three, liquid water is the most common agent of erosion because there's so much of it on the surface of the Earth. |
|
|
Term
|
Definition
Exfoliation (c) 2000 Andrew Alden, licensed to About.com, Inc. (fair use policy) Sometimes rocks weather by peeling off in sheets rather than eroding grain by grain. Exfoliation is scientific Latin for that process. It can happen in paper-thin layers on individual boulders, or it can take place in thick slabs as it does here, in Yosemite Valley, California. The great white granite domes and cliffs of the High Sierra, like Half Dome, owe their appearance to this type of exfoliation. These rocks were emplaced as molten bodies, or plutons, deep underground, raising the Sierra Nevada range. Erosion then unroofed the plutonic rocks and took away the pressure of the overlying rock. As a result, the solid rock acquired fine cracks through pressure-release jointing. The combined work of gravity, weathering, plant roots, and the expansion of freezing water opened up the joints further and loosened these slabs. |
|
|
Term
|
Definition
The chemical reaction of a compound with water. Hydrolysis is an important component of soil formation, and of chemical weathering—for example, as feldspars in granite decompose to make china clay. |
|
|
Term
|
Definition
When water infiltrates fractures in rock and freezes, the force of expansion is great enough to break
the rock into smaller pieces. |
|
|
Term
|
Definition
| A landslide is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments. Although the action of gravity is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability. Typically, pre-conditional factors build up specific sub-surface conditions that make the area/slope prone to failure, whereas the actual landslide often requires a trigger before being released |
|
|
Term
|
Definition
Mass movement is the down slope movement of earth materials under the influence of gravity. The detachment and movement of earth materials occurs if the stress imposed is greater than the strength of the material to hold it in place. Shear strength is a measure if the resistance of earth materials to be moved. The interlocking of soil particles increases the ability of material to stay in place. Plant roots also help bind soil particles together. Shear stress is primarily a function of the force exerted by the weight of the material under the influence of gravity acting in the down slope direction. The slope of the surface determines the amount of stress that occurs on earth materials. Water destabilizes hill slopes by creating pressure in the pore spaces of earth materials. Water infiltrating into slope materials saturates the soil particles at depth by filling the pore spaces between. The weight of water lying above creates water pressure that drives soil particles apart. This lessens the friction between them and enables them to slip past one another. Material is mobilized when the shear stress imposed on a surface exceeds the shear strength. The movement, especially in the case of slides and slumps, is along a failure plane. The failure plane may be a well-defined layer of clay or rock upon which sets the destabilized surface material. Humans induce mass movement when subjecting a slope to a load that exceeds its ability to resist movement. People building houses on scenic hill slopes often find their homes threatened by a landslide. Undercutting of hillsides during road construction commonly creates unstable slopes making them prone to failure. |
|
|
Term
mechanical weathering [image] |
|
Definition
Weathering is the decomposition of earth rocks, soils and their minerals through direct contact with the planet's atmosphere[1]. Weathering occurs in situ, or "with no movement", and thus should not to be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, wind, and gravity. Two important classifications of weathering processes exist — physical and chemical weathering. Mechanical or physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions, such as heat, water, ice, and pressure. The second classification, chemical weathering, involves the direct effect of atmospheric chemicals or biologically produced chemicals (also known as biological weathering) in the breakdown of rocks, soils, and minerals. The materials left over after the rock breaks down combined with organic material creates soil. The mineral content of the soil is determined by the parent material, thus a soil derived from a single rock type can often be deficient in one or more minerals for good fertility, while a soil weathered from a mix of rock types (as in glacial, eolian or alluvial sediments) often makes more fertile soil. |
|
|
Term
|
Definition
A mudflow or mudslide is the most rapid (up to 80 km/h / 50 mph) and fluid type of downhill mass wasting. It is a rapid movement of a large mass of mud formed from loose earth and water. Similar terms are debris flow (e.g. in high mountains), mudslide (not very liquid) lahars and mud stream (e.g. from volcanoes; see also lahar). |
|
|
Term
|
Definition
| OxidationOxidation is defined as the interaction between oxygen molecules and all the different substances they may contact, from metal to living tissue. Technically, however, with the discovery of electrons, oxidationoxidationoxidation came to be more precisely defined as the loss of at least one electron when two or more substances interact. Those substances may or may not include oxygen. (Incidentally, the opposite of oxidationoxidationoxidation is reduction — the addition of at least one electron when substances come into contact with each other.) Sometimes oxidationoxidationoxidation is not such a bad thing, as in the formation of super-durable anodized aluminum. Other times, oxidationoxidationoxidation can be destructive, such as the rusting of an automobile or the spoiling of fresh fruit. |
|
|
Term
|
Definition
| Parent material, in soil science, means the underlying geological material (generally bedrock or a superficial or drift deposit) in which soil horizons form. Soils typically get a great deal of structure and minerals from their parent material. Parent materials are made up of consolidated or unconsolidated mineral material that has undergone some degree of physical or chemical weathering. |
|
|
Term
|
Definition
| The soil that is remaining after the soluble elements have been dissolved - residual clay. Derived forms |
|
|
Term
|
Definition
Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is made up of broken rock particles that have been altered by chemical and environmental conditions, affected by processes such as weathering and erosion. Soil is different from its parent rock(s) source(s), altered by interactions between the lithosphere, hydrosphere, atmosphere, and the biosphere.[1] It is a mixture of mineral and organic constituents that are in solid, gaseous and aqueous states.[2][3] Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain sol solution (liquid) and air (gas).[4] Accordingly, soils are often treated as a three state system.[5] Most soils have a density between 1 and 2, and weigh between 60 and 120 pounds per cubic foot. [6] Soil is also known as earth: it is the substance from which our planet takes its name. |
|
|
Term
|
Definition
Soil is naturally removed by the action of water or wind: such 'background' (or 'geological') soil erosion has been occurring for some 450 million years, since the first land plants formed the first soil. Even before this, natural processes moved loose rock, or regolith, off the Earth's surface, just as has happened on the planet Mars. In general, background erosion removes soil at roughly the same rate as soil is formed. But 'accelerated' soil erosion — loss of soil at a much faster rate than it is formed — is a far more recent problem. It is always a result of mankind's unwise actions, such as overgrazing or unsuitable cultivation practices. These leave the land unprotected and vulnerable. Then, during times of erosive rainfall or windstorms, soil may be detached, transported, and (possibly travelling a long distance) deposited. Accelerated soil erosion by water or wind may affect both agricultural areas and the natural environment, and is one of the most widespread of today's environmental problems. It has impacts which are both on-site (at the place where the soil is detached) and off-site (wherever the eroded soil ends up). More recently still, the use of powerful agricultural implements has, in some parts of the world, led to damaging amounts of soil moving downslope merely under the action of gravity: this is so-called tillage erosion. Soil erosion is just one form of soil degradation. Other kinds of soil degradation include salinisation, nutrient loss, and compaction. |
|
|
Term
|
Definition
Soil Profile refers to the layers of soil; horizon A, B, and C. If you're wondering what horizon A is, here's your answer: horizon A refers to the upper layer of soil, nearest the surface. It is commonly known as topsoil. In the woods or other areas that have not been plowed or tilled, this layer would probably include organic litter, such as fallen leaves and twigs . The litter helps prevent erosion, holds moisture, and decays to form a very rich soil known as humus. Horizon A provides plants with nutrients they need for a great life. The layer below horizon A, of course, has to be horizon B. Litter is not present in horizon B and therefore there is much less humus. Horizon B does contain some elements from horizon A because of the process of leaching. Leaching resembles what happens in a coffee pot as the water drips through the coffee grounds. Leaching may also bring some minerals from horizon B down to horizon C. If horizon B is below horizon A, then horizon C must be below horizon B. Horizon C consists mostly of weatherized big rocks. This solid rock, as you discovered in Soil Formation, gave rise to the horizons above it. Soil profiles look different in different areas of the world. They are affected by climate and other things. Click here to see three different soil profiles |
|
|
Term
|
Definition
| Subsoil (also called substrata) is the layer of soil under the topsoil on the surface of the ground |
|
|
Term
|
Definition
| Topsoil is the upper, outermost layer of soil, usually the top 2 to 8 inches. It has the highest concentration of organic matter and ... |
|
|
Term
|
Definition
When you think of soil you think about dirt, right? In theory, soil is only what you find under your feet and dirt is what you find under your finger nails. However, soil actually has more depth and characteristics than that. It is the accumulation of loose, weathered material that covers much of the land surface of Earth. Soil varies in depth, composition, age, color, and texture. Although its chief component is weathered rock, a true soil also contains water, air, bacteria, and decayed plant and animal materials (humus). The rock from which a soil forms is called the parent material. Soil that forms directly from the bedrock beneath it is residual soil.
If the soil forms from material that was transported to the location by erosion, it is transported soil. Soil is the organic remains of decomposed vegetation. In agricultural soil, it is the medium that supports crop plants, both physically and biologically. Soil may be from a few inches to several feet thick. The inorganic fraction of soil may include various sizes and shapes of rocks and minerals, in order of increasing size. These are clay, silt, sand, gravel, and stone. Coarser soils have lower capacity to absorb organic plant nutrients, gases, and water, which are important for plants. Soils tend to absorb substances, so therefore they are usually better suited for agriculture.
|
|
|
Term
|
Definition
Weathering is the decomposition of earth rocks, soils and their minerals through direct contact with the planet's atmosphere [1]. Weathering occurs in situ, ... |
|
|
