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29 Cards in this Set
- Front
- Back
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Weathering |
Surface processes that work to break rock down. Weathering breaks rocks into gradually smaller pieces. |
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Soil texture |
The size of grains in various soil samples. Different levels and types of weathering break rocks, organic matter, etc. down into different sizes and in different ways. |
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How can you see weathering today? |
Look out your window... Are there any hills? Those might have. Once been larger hills, or even mountains! Rocks on the tops of mountains are broken down by weathering, then their sediments are pulled downhill by gravity where they mix with other sediments. |
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Mechanical Weathering |
This occurs when rocks are broken apart by natural processes. Plants and animals can break rocks apart in many ways. When rocks are broken down by chemical weathering they all have same chemical composition as the mother rock. |
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What can cause mechanical weathering? |
Animals burrowing in sections of rock/ plants (especially tree roots) can grow into the cracks of rocks and make them bigger. |
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Ice wedging |
Ice wedging normally occurs in cold and temperate climates where the temperature can change from warm to cold relatively quickly. Water runs between rocks and into their cracks where it freezes overnight. When water freezes, it expands. This causes more mechanical weathering. Ice wedging is also commonly seen in roads. |
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Regarding surface area |
Mechanical weathering weathers rocks into smaller pieces, creating more surface area. These smaller pieces have more surface area than the original rock. |
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Chemical weathering |
Chemical reactions dissolve or alter the minerals in rocks and change them into different minerals. |
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Natural Acids (that aid in chemical weathering) |
When water reacts with it's surroundings (air or soil), a week natural acid called carbonic acid forms. This acid reacts with calcite, a common mineral in many rocks. |
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How does Kaolinite clay form? |
After a long time the mineral feldspar (found in granite) is broken down to form this clay. |
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Plant acids |
The roots of a few plants give off acids that dissolve some minerals in rock. This weakens the rock, once it breaks down, it's nutrients are available in the soil for plants to use |
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Ph scale |
The ph scale measures the strength of acid (or the baseness of bases) on a scale of 0-14. 0 is very acidic. 14 is very basic, 7 is neutral. |
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Oxidation |
Oxygen is another thing that can cause chemical weathering. When minerals containing iron are exposed to water, the iron inside of this mineral reacts to oxidation in a new substance that looks like rust. |
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Climate |
Climate is a pattern of weather that is consistent in a certain area for many years. |
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Effects of rock type |
Some rocks weather faster than others. In wet climates marble weathers faster than granite. |
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Soil |
Soil is a mixture of weathered rock, decayed organic matter (tree bark, leaves, etc.), mineral fragments, water, and air. |
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Time it takes for soil to form (and important factors that affect amount of time) |
Climate, slope, types of rock, types of vegetation, and length of time rock has been weathering all affect how long it takes for rock to become soil. |
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Humus |
A dark colored material made of decayed organic matter, humus is a huge source of nutrients for plants. As animals dig through soil (worms, insects, etc.) they mix humus with soil |
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Organic matter |
Plant leaves, stems, roots, dead animals, microorganisms, poop |
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Water infiltration |
Soil has a lot of tiny air pockets between each soil particle. These spaces are normally full of water that plants use along with nutrients, etc. |
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Infiltration rate |
This is determined by calculating the time it takes for water sitting on top of soil takes to drop a fixed distance. |
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Soil profile |
The different layers of soil (horizons) that make up the soil profile. |
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A Horizon |
Top layer of soil, may be covered in litter. The A horizon is known as topsoil. Topsoil has more humus and fewer rock and mineral particles than other horizons. The dark color of the soil in this horizon is because it contains much dark humus. |
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B Horizon |
2nd layer in the soil profile. Also known as subsoil. It is lighter in color than the A horizon because is contains less humus and nutrients. The B horizon is less fertile because of this. The B horizon contains material that is brought down from the a horizon by a process known as leaching. |
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C horizon |
The C horizon made up of partially weathered rock and soil from the A and B horizons above it. The sediment in this horizon is very coarse and does not contain very much organic material because leaching does not normally reach this lower level. However without the sea horizons the A and B horizons would not be possible because the A and B horizons' rock is from the C horizon. |
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Leaching |
Leaching is the removal of minerals that have been dissolved in water. Water travels from the A horizon to the B horizon and the water takes some of the minerals from the A horizon to the B horizon with it. |
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Litter |
Litter is made up of leaves, twigs, and other organic material that can be changed to humus by decomposing organisms. Litter helps prevent erosion and evaporation of water from soil. Essentially, litter is like the first stage of humus. |
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Soil structure |
There are four different classes of soil structure there's platy, granular, prismatic, and blocky. Granular structures are common in surface structures and soil. Platy structures are often found in subsurface soils that of been leached. Blocky structures are common in subsoils and surface soils with high clay content. Prismatic structures found in the B horizon are very dense and hard for plant roots to penetrate. |
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Soil Types |
There are many different soil types. Soil type for flecked climate some are thick and red some are brown with hard rock nodules and some have thick black A horizons they vary in color, depth, Texture, fertility, pH, temperature, and moisture content. Soil type also depends on some other factors like parent Rock, ph, and slope. |
