Weathering and Soil

What aids water in dissolution?

Dissolution is usually aided by small amounts of acid in the water

What is eluvation?

washing out of fine soil components, clay is getting washed out

How does biological activity contribute to soil formation?

Burrowing animals and plant roots aerate the soil. The partial decay of plant material and animal remains produces the organic material and nutrients in soil. Decomposing organisms also create organic acids that increase the rate of weathering and soil formation. Bacteria in the soil change atmospheric nitrogen into nitrates.

How is carbonic acid formed?

Carbonic dioxide combines with water as raindrops fall through the atmosphere.

In what type of climate is chemical weathering most effective?

Chemical weathering is most effective in areas of warm, moist climates

What chemical weathering process involves minerals being altered to clay by reacting with water and acids? How does this process work?

Hydrolysis- Instead of dissolving the rock, the water combines with the rock and alters the minerals.

Know the difference between regolith and soil.

Regolith, is the layer of mineral and and rock fragments. Soil is minerals, organic matter, water, and air.

What is the difference between residual and transported regolith?

Residual: it has resided there, it stayed in place, forming in place. Transported: the rock material came from somewhere else.

What is produced when oxygen combines with iron-bearing minerals?

Rusting

Why does topography affect soil formation?

The steeper the slope, the less likely material will be able to stay in place to form soil. Material on a steep slope is likely to go downhill. Materials will accumulate and soil will form where land areas are flat or gently undulating.

What are some examples of mechanical weathering and what do they do in order to mechanically weather the rock?

They break larger rocks into smaller rocks, Examples: burrowing animals, plant root growth, human activity, daily fluctuations in temperature, abrasion, frost wedging, exfoliation or unloading.

What is the most important agent of chemical weathering, and why?

Water because, it is an excellent solvent, and it transports ions and molecules involved in chemical processes.

What is frost wedging? How and why does it occur?

Water enters cracks in rocks and upon freezing, expands and enlarges the crack.

What must a soil contain in order to be called soil.

Water, air, minerals, and organic matter.

What process involves the physical breakdown and chemical decomposition of rock?

Weathering

How is weathering important to life?

Weathering is important to life by making a regolith.

What types of climates make more soil? Why?

Wet, Warm climates will make more soil. Increased temperature increases the rate of chemical reactions, which also increases soil formation.

What is leaching?

depletion of soluble material, dissolved pieces are getting washed through

Why is quartz so common in sediment and in sedimentary rocks?

Because it is very resistant, it is resistant because it forms at a lower temperature.

What is exfoliation/unloading/sheeting? What Causes it?

-Overlying rock is eroded away, causing a reduction in pressure. -Outer layers of rock expand more than the rock below and separate from the rock body. -Rock breaks off as leaves or sheets, called sheeting. Makes Exfoliation domes Newly cut mine tunnels can have large slabs of rock explode off the walls...Why?Rapid reduction in pressure

What are the factors that control soil formation?

-Parent material -Time -Climate -Biological activity -Topography (shape of the land)

How is acid rain formed?

Pollutants, such as sulfur and nitrogen, from fossil fuel burning, create sulfuric and nitric acid. Forms acid rain, which accelerates chemical weathering

How does composition affect the rate of weathering? What happens to rocks containing calcite? Silicate minerals?

-Rocks containing calcite (marble and limestone) readily dissolve in weakly acidic solutions -Silicate minerals weather in the same order as their order of crystallization

How did the regolith on the Moon form?

Derived from meteorite impacts.

What is Bowen's Reaction Series? What does it help us to understand?

Describes the order that minerals form as magma cools. Also shows the order that minerals will weather.

What are the major processes of chemical weathering?

Dissolution, Hydrolysis, and Oxidation.

Which soil horizon is the zone of eluvation and leaching?

E Horizon

What process involves the physical removal and transport of material by nature, such as running water, wind, or ice?

Erosion

What happens to the feldspars when granite is weathered? The quartz? The mafics?

Feldspars will undergo hydrolysis to form clay (kaolinite), and Na and K ions are released and washed away. Mafic minerals will oxidize to form iron oxides, and also experience hydrolysis, turning them to clay. Quartz it does not weather, its just going to sit there.

What characteristics of minerals will make them more resistant to weathering? Why?

Harder materials, and ones with more cleavages will make them more difficult to break into smaller pieces, making them more resistant to mechanical weathering.

What its abrasion? Provide examples of how abrasion occurs.

In abrasion one rock bumps into another rock. Examples: (1) Gravity causes abrasion as a rock tumbles down a mountainside or cliff. (2) Moving water causes abrasion as particles in the water collide and bump against one another. (3)Strong winds carrying pieces of sand can sandblast surfaces. (4)Ice in glaciers carries many bits and pieces of rock. Rocks embedded at the bottom of the glacier scrape against the rocks below.

What process involves the transfer of rock and soil downslope under the influence of gravity?

Mass Wasting

What are the two types of weathering? What is the basic end result of each of these processes?

Mechanical Weathering- physically breaking rocks into smaller pieces, does not change its composition and Chemical Weathering- The internal structure of a mineral is altered by the removal and/or addition of elements.

Do mechanical and chemical weathering work independent of each other? Explain.

Mechanical, and chemical weathering work together. The smaller the pieces the more surface area, the more surface are the more exposed it is.

Does the moon have soil? Why or why not?

No it is not soil because it is missing water, air, and organic matter

Know the order of each horizon of the soil profile.

O Horizon A Horizon E Horizon B Horizon C Horizon

Know the characteristics of each soil horizon.

O Horizon- Has a lot of organic matter A Horizon- Has a lot of decayed material, it is called humus E Horizon- Little organic material- Eluvation and Leaching B Horizon- everything from above, accumulation of clay transport from above C Horizon- partially altered material... (SEE that's all of it)

Which chemical weathering process involves electrons being lost from an element?

Oxidation

What does frost wedging produce at the base of a cliff?

Talus- an accumulation of rock debris at the base of a cliff. Frost wedging produces talus slopes.

How does the temperature of formation contribute to how stable the mineral is on the surface?

The lower the temperature of formation, the more stable it is here on the surface...the more difficult it is to weather.

How does surface affect the rate of weathering?

The more surface that is exposed the more it can be weathered. Mechanically breaking it, being broken into smaller pieces will allow for it to be chemically weathered faster.

What is humus? Why is it important?

remains of animal and plant life..