Geology - Chapter 7: Weathering, Soils, and Paleosols

All of the answers are correct

Ancient climate and ecosystems can be inferred from paleosols by studying ______ found within the paleosols.

An abundance of C3 plants and a wetter, cooler climate

Ancient climate can be inferred from paleosols based on the δ13C measurements.A δ13C measurement of -13 means _______.

Rock exposures at high altitude and high latitudes

At which of the following geographic locations might you expect the effects of freeze-thaw weathering (frost wedging) to be most influential?

K+ and silica

During the chemical weathering (hydrolysis) of muscovite and potassium feldspar, which two end-products are dissolved in solution and carried throughout the surface as groundwater systems.

Mg2+ and silica

During the chemical weathering (hydrolysis) of olivine, which two end-products are dissolved in solution and carried throughout the surface and groundwater systems.

Oxidation of ferromagnesian minerals in the scoria

Fresh lava of basaltic composition is black, why is this piece of scoria red?

Erosion

The physical removal of material by mobile agents such as water, wind, or ice is referred to as ______.

The physical breakdown and chemical alteration of rocks at or neat Earth's surface

The process of weathering is best described as ______.

All the answers are correct.

The rate of weathering is influenced by ______.

Anions

The small size and positive charge of a hydrogen ion make it easy for hydrogen to substitute for _______ within a crystal lattice.

O Horizon

The top layer in the image is representative of which horizon?

Dissolution of calcite

The weathering process depicted in the image above is called ______.

False

True or False: Caliche is a hardpan soil made of silica and is found mainly in humid climates.

True

True or False: Chemical weathering of rocks is enhanced by increased mechanical weathering.

True

True or False: Extremely wet climates, like tropical rain forests, will produce highly leached and unproductive soils called laterites.

False

True or False: Feldspars found in sediment or sandstone indicates fast chemical weathering in an arid environment.

False

True or False: The rate of chemical weathering is greatly increased in cold and arid climates.

Exfoliation Domes

Unloading and sheeting are associated with ______.

Water in which CO2 is dissolved. It produces carbonic acid which contributes to hydrolysis and the breakdown of silicate and carbonate minerals.

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

Hydrolysis

A complicated series of chemical reactions involving acidic water, and exposed silicate minerals in which the reaction products are clay minerals, dissolved silica, and free cations in solution is called ______.

Soil

A paleosol is a fossil ______ that has been preserved in the geologic record.

An increase, warming

An increase in plate tectonic activity, such as continental rifting, and mid-ocean ridge development, coupled with subduction and volcanic arc formation, results in ______ in CO2 in the atmosphere and ______ of the climate.

Mechanical weathering

The physical disintegration of rocks into smaller pieces is called ______.

Amphibole, Biotite

If the original mineral composition of the granite were amphibole, biotite, K-feldspar, Na-feldspar and quartz, which mineral or minerals weathered first?

Caliche

In arid environments, an accumulation of calcite within the A-horizon results in a hardpan duricrust of calcium carbonate called ______.

Warm and humid

In which climate would the rate of chemical weathering likely be the highest?

Arid regions or an oceanic coastline

In which of the following areas would salt wedging be the most effective form of weathering?

Moist areas with warm temperatures

In which of the following climates is chemical weathering most effective?

Oxidation of iron

Iron oxides, like hematite and limonite, are the product of which one of the following weathering processes?

Rhizoliths

Mineralized molds casts of plant roots found in paleosols are called ______.

The chemical weathering of granite

Nearly all quartz that make up beach sand, terrestrial sand, and the vast sandstone beds of the world originated from ______.

Mechanical

Of the two types of weathering processes, ______ weathering is accomplished by physical forces that break rock into smaller and smaller pieces without changing the rock's mineral composition.

R, C, A, B, E, O

Soil Horizon Development. List the soil horizons in order of formation from first to last in a mature residual soil.

Clay minerals + Ions in solution

The chemical weathering of silicate minerals frequently produces _______.

All of the answers are correct

The complete chemical weathering of granite (composed of feldspar, quartz, amphibole, and biotite) yields

Chemical weathering

The decomposition of rocks and minerals by exposure to water and atmospheric gases is known as ______.

Dissolution of calcite

The formation of caves in limestone bedrock is associated with which form of chemical weathering?

Caliche, ocean

The image above shows a trail on Camelback Mountain in central Phoenix. In the image above, the white calcium carbonate coating on the trail and just underneath the thin sandy soil is called ______, and when found in a paleosol, indicates the ancient environment was a ______.

Nothing. Quartz does not undergo chemical weathering.

The most common end product of the chemical weathering of quartz is ______.

Carbonic Acid

The most important and the most abundant agent of chemical weathering is ______.

Residual soil is produced from the breakdown of bedrocks in situ, whereas transported soil is produced from sediment that has been deposited elsewhere.

What is the difference between residual soil and transported soil?

Frost Wedging

What type of weathering process is depicted in the image above?

Root wedging

What type of weathering process is depicted in the image above?

Mechanical weathering

When a rock undergoes ______, such as frost wedging the rock is broken into smaller and smaller pieces.z

Increases by about 9%

When water freezes, it's volume ______.

Quartz

Which mineral is the least susceptible to chemical weathering and forms sand grains on beaches, dunes, and the extensive worldwide occurrence of sandstones.

Frost wedging is a cyclic process by which water in fractures freezes at night, expanding the space between blocks of rock. During daytime, the ice melts and the process begins again.

Which of the following best describes frost wedging?

Quartz, potassium feldspar, amphibole, olivine

Which of the following list the minerals in order of decreasing rate of chemical weathering (Slowest to fastest)

Olivine

Which of the following minerals will weather most rapidly at Earth's surface?

Iron oxides

Which one of the following is NOT a product of the complete chemical weathering (hydrolysis) of the mineral potassium feldspar (KAlSi3O8).

E Horizon

Which soil horizon is the light-colored layer located at the bottom of the image?

The E horizon; leaching and eluviation

Which soil horizon is typically a light-colored whitish layer containing no organic matter, whitish quartz, and is devoid of any iron, aluminum, or clay. And what process or processes are responsible?

All the answers are correct.

Which statement is true about a mineral's resistance to chemical weathering?

It causes a major change in mineral composition.

Which statement regarding mechanical weathering is NOT true?

Silica, Hematite

_______ and _______ are the most common natural cementing agents in clastic sedimentary rocks, and are the byproducts of the weathering process. (Hint: one of them makes the some sandstones look red).