Chapter 5 Flashcards
What has to happen to a body of rock before exfoliation can take place?
Before a rock can be exposed at surface it has to be uplifted from where it formed deep in the crust, and the material on top has to be eroded.
The climate of central B.C. is consistently cold in the winter and consistently warm in the summer. At what times of year would you expect frost wedging to be most effective?
Frost wedging is most effective at times when the weather swings between freezing at night and thawing during the day. In cold parts of B.C. that only happens consistently in spring and fall. In warmer regions it only happens consistently during the winter.
What are the likely products of the hydrolysis of the feldspar albite (NaAlSi3O8)?
Under conditions of strong chemical weathering, feldspar albite (NaAlSi3O8) will be converted to a clay (such as kaolinite) and sodium ions in solution. Where mechanical weathering is predominant, albite will be broken into small pieces.
Oxidation weathering of the sulphide mineral pyrite (FeS2) can lead to development of acid rock drainage (ARD). What are the environmental implications of ARD?
Acid rock drainage (ARD) creates acidic stream runoff and also enhances the solubility of a wide range of metals, some of which can be toxic.
Most sand deposits are dominated by quartz, with very little feldspar. Under what weathering and erosion conditions would you expect to find feldspar-rich sand?
Feldspar-rich sand is formed in areas where granitic rocks are being weathered and where mechanical weathering is strongly predominant over chemical weathering.
What ultimately happens to most of the clay that forms during the hydrolysis of silicate minerals?
Most of the clay that forms during hydrolysis of silicate minerals ends up in rivers and is washed out to the oceans. There it eventually settles to the sea floor.
Why are the slope and the parent materials important factors in soil formation?
The mineral composition of the parent rock or sediment will influence the composition of the resulting soil. Slope is important because it will affect the degree to which materials will be eroded.
Which soil constituents move downward to produce the B horizon of a soil?
Clay minerals and iron move downward to produce the B horizon of a soil.
What are the main processes that lead to the erosion of soils in Canada?
Removal of vegetation leaves soil exposed to erosion by water, and wind are the main processes of soil erosion in Canada.
Where in Canada would you expect to find a chernozemic soil? What characteristics of this region produce this type of soil?
Chernozemic soils are common in the southern prairies and parts of the BC southern interior, in areas that experience water deficits during the summer.
Where are luvisolic soils found in B.C.?
Luvisolic soils are found in central B.C., mostly over sedimentary rocks.
Why does weathering of silicate minerals, especially feldspar, lead to consumption of atmospheric carbon dioxide? What eventually happens to the carbon that is involved in that process?
The weathering feldspar to clay involves the conversion of atmospheric carbon dioxide to dissolved bicarbonate, which ends up in the ocean.
