Geol 1330 Chap 6

Oxidation:

Any reaction when electrons are lost from one element

Spheroidal wreathing:

Any weathering process that tends to produce a spherical shape from an initially blocky shape.

Chemical weathering:

Chemical reactions between minerals and external agents like air or water(most important)

Transported soil:

Derived from elsewhere, Deposited in lowland, valley or basin

Chemical weathering is most effective in warm climates. Rocks do not adhere to local and regional factors. Results are huge spectacular formations.Surface area-rocks containing calcite (limestone and marble are easily dissolved in small amounts of acid.

Describe how each of the following factors affects the rate of rock weathering: surface area, minerals comprising the rock, climate (rainfall & temperature), soil cover, zones of weakness (i.e. fractures and bedding planes), and organic activity

. Silicates + water = clays +(-) dissolved substances

Describe the overall process of the weathering of silicates to clays

What is Soil Taxonomy? What are the characteristics used to classify soils?

Emphasis is placed on physical and chemical properties - Six hierarchical categories exist - Descriptive names are derived from Latin and Greek - 12 basic soil orders are recognized

Exfoliation

Large, flatly curved sheets of rock separate and spall off the main rock body

Alternating heat and cold:

Repeated expansion and contraction of a rock during heating and cooling. Common in desert regions that experience hot days and cold nights

Mechanical weathering:

Rocks broken down by physical processes such as fracturing, freezing-thawing, and breakage during transport

Hydrolysis:

The reaction of any substance with water, Hydrogen ion attacks and replaces other ions

Eluviation:

The washing out of fine soil components from the A horizon by downward-percolating water.

Parent material:

Type of rock(s) weathered to produce soil

Frost Wedging

Water in fractures expand when freezing, prying rocks apart

Oxygen and acids

What are the two primary external agents of chemical weathering?

Feldspar alters to clay (kaolinite) plus dissolved materials (ions) biotite and/or amphibole will undergo hydrolysis to form clay, and oxidation to form iron oxides

What are the ultimate products of chemical weathering of feldspar, biotite and amphibole?

only transport clean soil with not pesticides, natural erosion just happens.

What can be done to slow down or prevent soil erosion

Mineral and organic matter, water and air weathered rocks that break down

What comprises soil? How is soil formed?

Are soil types rich in iron and aluminum, formed in hot and wet tropical areas. Nearly all laterites are rusty-red

What is laterite soil? What type of climate is associated with laterite soil?

B

zone of accumulation

Hematite > Quartz > Clay minerals > Na-plagioclase > Amphibole > Ca-plagioclase > Olivine > Calcite > Halite

12. Given the following minerals: halite, calcite, clay minerals, olivine, quartz, hematite, amphibole, Ca-plagioclase, Na-plagioclase; Rank these minerals in order of decreasing resistance (greater susceptibility) to chemical weathering.

Influence the soil's physical and chemical properties. Tree's roots split rocks

14. How does organic activity, such as the growth of tree roots, contribute to mechanical weathering?

Soil:

A combination of mineral and organic matter, water, and air; that portion of the regolith that supports plant growth.

Dissolution:

A common form of chemical weathering, it is the process of dissolving into a homogeneous solution, Aided by small amounts of acid in the water

Horizon (soil)

A layer in a soil profile.

Internal processes:

A process such as mountain building or volcanism that derives its energy from Earth's interior and elevates Earth's surface.

Laterite:

A red, highly leached soil type found in the tropics that is rich in oxides of iron and aluminum

Soil Taxonomy:

A soil classification system consisting of six hierarchical categories based on observable soil characteristics. The system recognizes 12 soil orders.

Soil profiling:

A vertical section through a soil, showing its succession of horizons and the underlying parent material.

Talus slope:

An accumulation of rock debris at the base of a cliff.

Calcite and Halite

Name two minerals that are particularly prone to dissolution.

Humus:

Organic matter in soil produced by the decomposition of plants and animals.

Sheeting

Outer layers of a large mass of granite break off as concentric slabs

What are the three types of chemical weathering?

Oxidation, hydrolysis, and dissolution

the factors that influence the type of soil that ultimately forms in a given region

Parent rock, climate, plants and animals, topography and time

External process:

Process such as weathering, mass wasting, or erosion that is powered by the Sun and contributes to the transformation of solid rock into sediment.

different factors that influence the rate of soil erosion?

Soil char, climate, slope, type of vegetation. Transportation of soil,

Residual Soil:

Soil developed directly from the weathering of the bedrock below.

Leaching:

The depletion of soluble materials from the upper soil by downward-percolating water.

Weathering:

The disintegration and decomposition of rock at or near the surface of Earth

Regolith:

The layer of rock and mineral fragments that nearly everywhere covers Earth's land surface. •Particles of parent rock, Clay minerals, Metal oxides, Organic matter

Explain how Bowen's Reaction Series can be used to predict the susceptibility of different silicate minerals to chemical weathering.

The order of crystallization in a cooling magma is also the order of chemical weathering in various igneous rocks. For example, in a mafic rock like basalt, the olivine crystals (which formed at a higher temperature) will typically decompose via chemical weathering before the pyroxene crystals (which formed at a slightly lower temperature).

The interaction between oxygen molecules and all the different substances they may contact the oxygen causes free radicals on the surface to break away. Apple turning brown.

What is oxidation? Describe the overall process of oxidation. Give an example of oxidation.

It is the 2nd most common mineral and it resists weathering better than any other mineral making it last longer.

Why is quartz so common in clastic sedimentary rocks?

O A

___ -organic matter __ - organic and mineral matter - High biological activity make up the topsoil.

E

little organic matter - Zone of eluviation and leaching

C

partially altered parent material Collectively the O, A, E, and B horizons = solum, or "true soil"

Erosion:

the physical removal of material by mobile agents such as water, wind, ice, or gravity

Mass wasting:

the transfer of rock and soil downslope under the influence of gravity