Geol. 1403/Cook quiz 6 part I
Clay minerals formed from gabbro or diorite bedrock illustrate which kind of weathering?
Why is the humus layer typically thicker in a cool , temperate, forest soil than in a tropical rainforest soil?
Less humus is produced in the cool, temperate forest but the rate of decay and oxidation is slower than in a tropical rainforest.
Frost wedging is the major weathering process contributing to the formation of which regolith material?
What portion of an angular, fracture-bounded granitic block shows the highest rate of weathering?
the edgesand corners
What describes a characteristic process in the formation of a pedalfer soil?
iron oxides and aluminum-rich clays are precipitated in the B-horizon
In the Rocky Mountain region of the U.S., north-facing slopes (downhill direction is toward the north) are typically more moist and heavily forested than south-facing slopes. Why?
north-facing slopes receive about the same amount of precipitation as south-facing slopes; less moisture evaporates from north-facing slopes.
Clay minerals, silica (SiO2), and disolved potassium bicarbonate in the soil water are products of what process?
chemical weathering of orthoclase feldspar
What two factors speed up rates of chemical reaction and weathering in rocks and soils?
warm temperatures; verymoist
In terrain with steep hill slopes, which crop and cultivation technique will minimize soil erosion?
apples, land between the trees is planted in grass and not cultivated.
From the land surface downward to the unweathered bedrock, what is the correct order of the different soil horizons?
O, A E, B, C, bedrock
What statement concerning mechanical weathering is not true?
Involves a major change in the mineral composition of the weathered material
The finely divided red, brown, and yellow soil-coloring materials originate by what process?
Precipitation of iron oxides during chemical weathering processes
What term describes a soil formed by weathering of the underlying bedrock?
What best describes the "Dust Bowl"?
areas of severe wind erosion on the Great Plains , 1930s.
What is an important, mechanical wethering process for enlarging fractures and extending them deeper into large boulders and bedrock?
What best desribes sets of fractures in relatively fresh bedrock, such as granite, that are roughly parallel to the land surface?
Assume that water filling a crack in a rock undergoes cycles of freezing and melting. What statement is true?
water expands as it freezes, causing the crack walls to be pushed apart.
What statement best describes erosion?
the process by which weathered rock and mineral particles are removed from one area and transported elsewhere.
Quartz weathers readily to aluminum-rich clay minerals.
Abundant moisture and warm temperatures result in high rates of chemical weathering.
Feldspars commonly decompose during wethering to caly minerlas, silica, and soluable constituents.
Humus is a concentration of decaying, organic matter in the B-horizons of lateritic soils.
Calcite a major component of some monumental and building stones, slowly dissolves in weakly acidic waters.
Like most other liquids, water decreases in volume when it freezes.
Chemical weathering in bedrock below the land surface often begins along joints and sheeting fractures.
Removal of soluable chemical constituents from a soil is termed leaching.
Oxidation of iron is an important chemical weathering process for ferromagnesian silicate minerals like olivine and biotite.
Sheeting is mainly a process of mechanical weathering.
Sheeting fractures and exfoliation domes commonly develop in areas with soft, highly fractured bedrock.
Quartz is quite resisitant to weathering and is an important component of sands in riverbeds and on beaches.
Very fine-grained iron-oxide particles account for nearly all red, yellow and brown soil colors.
32.) First level of soil layer is the ____.
(e) O horizon
33.) Second level of soil layer is the ____.
(a) A horizon
34.) Third level of soil layer is the ____.
(b) B horizon
35. Fourth level of soil layer is the ____.
(c) C horizon
36.) Fifth level of soil layer is the ____.
At which location would the thickest residual soil develop?
At which location would the greatest amount of frost wedging occur?
A which location would the thickest transported soil develop?
At which location would there be the most unconsolidated deposits?