Earth Science, Tarbuck Chap 8 Flashcards
Weathering, Mass movement, and erosion are all
External Processes
What are external processes
processes that occur using external energy, e.g. suns energy, gravity, etc.
What are internal processes
Processes that occur using earth’s internal energy
What is weathering
physical breakdown and chemical alteration of rocks near Earth’s surface
What is Mass movement
transfer of rock and
soil downslope under the influence of gravity
What is Erosion
physical removal and transport
of material by mobile agents such as water, wind, or ice
What is mechanical weathering
Weathering that uses physical forces that break rock into smaller and smaller pieces without changing the rock’s mineral composition
4 important physical processes that lead to fragmentation of rock
Frost Wedging, Salt Crystal Growth, Expansion resulting from unloading, and Biologic Activity
What percent larger does liquid get when freezing
9%
What is Frost Wedging
expansion of liquid in cracks of rock, causing the cracks to enlarge and angular fragments to be broken off.
What is Frost Heaving
expansion of moist soils during freezing.
What causes salt crystal growth in rocks that lead to the break down of rocks
First, sea spray or salty groundwater penetrates crevices and pore spaces in rock. As the water evaporates, the salt is left behind, forming salt crystals. As these crystals grow larger, they weaken the rock by pushing apart surrounding grains or enlarging tiny cracks
What is sheeting in igneous rocks
large masses of igneous rock, mostly in granite, are exposed by erosion, causing slabs of igneous rock to break loose.
why does mechanical weathering aid chemical weathering
Mechanical weathering leads to greater surface areas in rock, leading to more surface area exposed to chemical weathering
how does chemical weathering aid mechanical weathering
weakens outer portions of rock
_______ is the most important agent of chemical weathering
Water
What can make pure water reactive
small amounts of dissolved material
how is carbonic acid formed
Carbon Dioxide dissolved in Water
Carbonic Acid is a _________ solution
Acidic
Chemical Breakdown of feldspars generally lead to what mineral group as a product
Clay Minerals
What is spheroidal weathering process
Formation of circular rock outcrops due to weathering attacking edges and corners of rock more effectively than 1 face.
What is the order of least to most resistant silicate minerals
Olivine, Pyroxene, Amphibole, Biotite, Plagioclase feldspar, potassium feldspar, Muscovite, Quartz
What is the most optimal environment for chemical weathering
warm temperatures and abundant moisture
What is Regolith
layer of rock and mineral fragments produced by weathering
What is most soil made of
1/2 of soil is disintegrated and decomposed rock and decayed remains of animal and plant life. While the other half is pore spaces among solid particles where air and water circulate
What is humus
decayed remains of animal and plant life.
Best soil for plant growth
Loam
What is Loam?
Soil in which no single particle size dominates over the others.(Sand, Silt, and clay are in equilibrium )
Why is loam good for plant growth
hold moisture and nutrients better than other soils
What is the parent material of soil
source of the weathered mineral matter from which soils develop
What are Residual Soils
Soils whos parent material is bedrock
What are transported soils
Soils that develop on loose sediment
What is the most influential factor in soil formation
climate
he longer a soil has been forming, the _______ it becomes and the _____ it resembles the parent material.
Thicker, Less
Soils are often poorly developed on
Steep Slopes, due to rapid runoff
Why does slope orientation matter to soil formation
Different slope orientations receive different amounts of sunlight.
What are soil horizons `
zones of different soil due to soil-forming processes top-down
What is Leaching
depletion of soluble materials from the upper soil
What is elluviation
washing out of fine soil components. Also called leaching
What is Solum
“True Soil”
What are the 12 basic soil orders
Alfisol, Andisol, Aridisol, Entisol, Gelisol, Histosol, Inceptisol, Mollisol, Oxisol, Spodosol, Ultisol, Vertisol
What is Alfisol Soil order
moderately weathered soils formed under boreal forests or broadleaf deciduous forests, rich in iron and aluminum.
What is Andisol Soil order
young soils in which the parent material is volcanic ash and cinders, deposited by recent volcanic activity.
WHat is Aridisol Soil Order
soils that develop in dry places with insufficient water to remove soluble minerals; may have calcium carbonate, gypsum, or salt accumulation in subsoil;
low organic content.
What is Entisol Soil Order
young soils with limited development and exhibiting properties of the parent material.
What is Gelisol Soil Order
young soils with little profile development found in regions with permafrost. Low temperatures and frozen conditions for much of the year slow soil-forming
processes.
What is Histosol
organic soils with little or no climatic implications. Found in any climate where organic debris accumulates to form a bog soil. Dark, partially decomposed
organic material commonly referred to as peat.
What is Inceptisol Soil order
weakly developed young soils showing the beginning (inception) of profile development. Most common in humid climates but found from the arctic to the
tropics. Native vegetation is most often forest.
What is Mollisol Soil Order
dark, soft soils developed under grass vegetation, generally found in prairie areas. Humus-rich surface horizon that is rich in calcium and magnesium;
excellent fertility.
What is Oxisol Soil order
soils formed on old land surfaces unless parent materials were strongly weathered before they were deposited. Generally found in the tropics and
subtropical regions. Rich in iron and aluminum oxides, oxisols are heavily leached and hence are poor soils for cultivation.
What is Spodosol Soil order
soils found only in humid regions on sandy material. Common in northern coniferous forests and cool humid forests.
What is Ultisol Soil Order
soils representing the products of long periods of weathering. Percolating water concentrates clay particles in the lower horizons. Restricted to humid
climates in the temperate regions and the tropics, where the growing season is long.
What is vertisol Soil Order
Soils containing large amounts of clay, which shrink when dry and swell with the addition of water. Found in subhumid to arid climates if sufficient water is
available to saturate the soil after periods of drought.
What is Mass Wasting
The process of force of gravity causing rock and soil to move
downslope
What does mass Movement occur after
Weathering
Describe Evolution of a landscape over time
- Weathering weakens rock,
- Weathered rock is moved downslope where a stream or glacier acts as a conveyer belt,
- Rock is transferred into the Sea
Why do debris flows occur
When Pores in sediment become filled with water, the cohesion among particles is destroyed, leading to the particles slipping past each other freely.
What is Oversteepening of Slopes occur
As a slope becomes steeper, the forces that resist the downward pull of gravity get weaker
What is the Angle of Repose
The angle at which material becomes unstable
Why do plants protect against erosion and contribute to stability of slopes
root systems bind soil and regolith together
4 types of Rapid Mass Wasting
Slump, Rockslide, Debris Flow, EarthFlow
Describe Slump Mass Wasting
Downward sliding of a mass of rock or unconsolidated material moving as a unit along a curved
surface.
Describe Rockslide Mass Wasting
Blocks of bedrock break loose and slide very rapidly downslope
Describe Debris Flow Mass Wasting
A flow of weathered debris containing a large amount of water. Often confined to channels. Sometimes called a mudflow.
Describe Earthflow Mass Wasting
A tongue-like flow of water-saturated clay-rich soil on a hillside that breaks away and moves downslope.
2 Types of Slow Mass Movement
Creep, Solifunction
What is Creep Mass Wasting
gradual downhill movement of soil and regolith
What is Solifluction Mass Wasting
Soil is saturated with water, the
soggy mass may flow downslope at a rate of a few millimeters or a few centimeters per day or per year
Solifluction is Common in _____ areas
Permafrost
there are usually 6 soil horizons, list them from top down
O, A, E, B, C, R
Describe O soil horizon
Organic layer, consists mostly of humus
Describe A soil horizon
Topsoil, Minerals with Humus
Describe E Soil Horizon
Eluviation layer, Leached minerals and Organic Matter
Describe B Soil Horizon
Subsoil, rich in eluviated(leached) minerals and metal salts
Describe C Soil Horizon
Parent rock, partly weathered rock
Described R Soil Horizon
Bedrock, unweathered rock
