admin / January 25, 2018
Question Answer
Weathering is? general process by which rocks are broken down at the Earth's surface.
What does weathering produce? all the clays, soil, and dissolved substances carried by rivers to the ocean.
What are the two ways rocks weather? chemical and physical
Chemical weathering when minerals in a rock are chemically altered or dissolved. The blurring or disapearance of lettering on old gravestones and monuments is causedmainly by chemical weathering.
Physical weathering takes place when solid rock is fragmented by mechanical processes that do not change its chemical composition.
Erosion losen and transport soil and rock downhill or downwind. These processes carry away weathered material on Earth’s surface and deposit ierosion moves weathered solid material, it exposes fresh, unaltered rock to weathering.
What shapes the Earth's surface? weathering, erosion, tectonics and volcanism
What makes most of the dissolved matter in the oceans? chemical weathering
Four key factions that control fragmentation and decay of rocks 1. the properties of the parent rock 2. the climate 3. the presence or absence of soil 4. the length of time the rocks are exposed to the atmosphere
Properties of the parent rock are? 1. various minerals weather at different rates 2. a rock’s structure affects its susceptibility to cracking and fragmentation.
What increases the growth rate of organisms and promotes chemical weathering? high temperatures and heavy rainfall
What decreases the growth rate of organisms? cold and dryness
Rocks weather in two ways: Chemical weathering occurs when the minerals in a rock are chemically altered or dissolved. The blurring or disapearance of lettering on old gravestones and monuments is causedmainly by chemical weathering.
Soil is composed of fragments of bedrock, clay minerals formed by the chemical alteration of bedrock minerals, and organic matter produced by organisms that live in the soil.
Once soil starts to form it works as a geological agent to weather rock more rapidly. The soils retains rainwater, and it hosts a variety of vegetation, bacteria, and other organisms.
The longer a rock weathers the greater its chemical alteration, dissolution,and physical breakup.
Rocks that have been exposed at Earth’s surface for many thousands of years form a rind form? External layer of weathered material ranging from severalmillimeters to several centimenters thick – that surrounds the fresh, unaltered rock. In dry climates, some rinds have grown as slowly as 0.006 mm per 1000 years.
Feldspar is one of many silicates that are altered by chemical reactions to form water-containing minerals known as clay minerals. 1. there is an overwhelming abundance of silicate minerals in the Earth. 2. the chemical processes of dissolution and alteration that characterize feldspar weathering also characterize weathering in other kinds of minerals.
Extreme example of feldspar weathering is? Heavy rainfall, high temperature, the presence of soil, and abundance of organic activity weaken granite so they can be easily pounded into loose mineral grains.
Kaolinite is the white to cream-colored clay produced by? the weathering of feldspar
Kaolinite is named and used for? Named after Gaoling a hill in southwestern China where it was first obtained & used tomake pottery and china.
Water is the essential component of the chemical reaction when? feldspar becomes kaolinte
Kaolinite is a hydrous aluminum silicate. The solid feldspar undergoes hydrolysis, the feldspar is broken down and loses several components.
The reaction of feldspar with water releases? dissolved silica and dissolved potassium ions (K+) and leaves behind the new mineral kaolinite.
Potassium and silica are lost by the feldspar and appear as? dissolved materials in the water solution
Water is absorbed into the kaolinite crystal structure. This absorption of water is called? hydration and is one of the major processes of weathering.
Higher levels of carbon dioxide in the atmosphere lead to? higher levels in the soil, which increases the rate of weathering
Carbon dioxide promotes weathering by? making the Earth’s climate warmer
Weathering converts carbon dioxide into? bicarbonate ions
Bicarbonate ions decrease the amount of carbon dioxide in the atmosphere, which eventually results in? a cooler climate.
Weathering at the surface of a feldspar grain is linked to? the causes of global climate change.
When carbon dioxide is used up through weathering: the climate cools & weathering decreases again.
3 Things that happen as weathering decreases? the amount of carbon dioxide in the atmosphere builds up again, and the climate warms, thus completing the cycle
Carbon dioxide plus water yields? carbonic acid
The amount of carbon dioxide dissolved in rainwater is small because? the amount of carbon dioxide gas in the atmosphere is small.
Most of the acidity of acid rain comes from? sulfur dioxide and nitrogen gases, which react to form strong sulfuric and nitric acids
Industrial pollution is the largest source of carbon which are? Sulfur and nitrogen gases released into the atmosphere.
Rock weathers more rapidly in the tropics than in temperate and cold climates because? plants and bacteria grow quickly in warm, humid climates, contributiong the carbonic acid and other acids that promote weathering.
Olivine is? the most rapidly weathered silicate mineral, is relatively slow to dissolve compared to some other nonsilicate rock Chemical Stability:?
Slicate rocks are much more abundant than carbonate rocks such as limestone because? carbonate minerals dissolve faster and in greater amounts than silicates.
Chemical stability is a measure of? a substance’s tendency to remain in a given chemical form rather than to react spontaneously to become a different chemical substance.
Solubility of a specific mineral is measured by? the amount of the mineral dissolved in water when the solution is saturated.
Saturation is the point at which the water cannot? hold any more of the dissolved substance.
The higher a mineral’s solubility? the lower its stability under weathering.
Clays form through the weathering of? a variety of silicate minerals
Clays formed depend on two factors: 1. The composition of the parent silicates 2. The climate
The clay mineral montmorillonite forms from? the weathering of volcanic ash.
Bauxite is? an ore composed of aluminum hydroxide that is the major source of aluminum metal.
Bauxite forms when? clay minerals made from weathered silicates continue to weather until they have lost all their silica and ions other than aluminum.
Bauxite is found in? tropical regions, where rainfall is heavy and weathering intense.
Most of the iron ores used for the production of iron and steel are formed by? weathering
Ores are composed of iorn oxide minerals originally produced during? the weathering of iron-rich silicate minerals ex. pyroxene and olivine.
Three forms of Fe are: ferrous, ferric, and metallic iron.
All the iron fromed at the earth’s surface is? ferric.
The strength of the chemical bond between ferric iron and oxygen make ferric iron? insoluble in most natural waters.
Iron minerals weather to? the characteristic red and brown colors of oxidized iron.
Iron oxides are found as coatings and encrustations that color soils and weathered surfaces of iron – containing rocks. The red soils of warm, humid regions are colored by? iron oxides
Iron minerals weather so slowly in frigid regions that? iron meteorites freeze and are almost entirely unweathered
Physical weathering is the most common form of weathering in? dry regions
Physical weathering does not always depend on? chemical weathering
The freezing of water in cracks sometime break up? unweathered rock masses
Some rocks are more susceptible to weathering because of? the strains on the rock due to tectonism.
What Determines How Rocks Break? Natural Zones of Weakness
Joints are? massive rocks that tend to crack along regular fractures spaced several meters apart
Micro fractures are produced by? bacteria and algae invading cracks and roots, fungi, animals burrowing in cracks
Frost Wedging is? breakage due to the expansion of freezing water.
Steepness of slopes affects? physical and chemical weathering and the intensity of erosion.
The entire layer of weathered and unweathered parent rock, clay minerals, iron and other metal oxides, and other products of weathering are referred to as? Engineers: soil, Geologists: regolith
A-horizon: soil’s topmost layer, typically not much more than a meter or two thick, usually the darkest layercontaining the highest concentration of organic matter.
B-horizon: layer where organic matter is sparse, soluble minerals and iron oxides have accumulated in small pods, lenses and coatings.
C-horizon: slightly altered bedrock, broken and decayed, mixed with clay from chemical weathering.
The transition from one horizon to another is usually? indistinct
Residual soils evolve in one place from bedrock to? well developed soil horizons
Transported soils may accumulate in? limited areas of lowlands after being eroded from surrounding slopes and carried downhill
These soils owe their thickness to? deposition rather than to weathering in place
Temperate Climates: Pedalfers
Wet Climates: Laterites
Dry Climates: Pedocals
Paleosols: working backward from soil to climate
Paleosols are? ancient soils that have been preserved as rock in the geologic record

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