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60 terms

Weathering, Sedimentary and Metamorphic Rocks

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The Rock Cycle
the processes by which rock is formed, modified, transported, decomposed, and reformed as a result of the Earth's internal and external processes.
Weathering
The chemical and physical breakdown of rocks exposed to air, moisture, and organic matter.
Regolith
The loose layer of broken rock and mineral fragments on the Earth's surface.
Mechanical Weathering
rock is physically broken up, but there is no change in the mineral content or chemical composition.
Chemical Weathering
the decomposition of rocks and minerals as a result of chemical and biochemical reactions.
Hydrolysis
A type of chemical weathering that is leads to the change in silicate minerals to salt and clays.
Oxidation
A type of chemical weathering that alters iron and manganese by exposure to oxygen.
Quartz
is very resistant to weathering and does not dissolve quickly or have an ion exchange.
Rock Structure
If there are many cracks or joints in a rock, water can get in and weather rocks more quickly through its
Soil
The uppermost part of the regolith, the part that supports rooted plant life.
Humus
Partially decayed organic matter.
Soil Horizons
A succession of zones within a soil profile with distinct physical, chemical, and biological characteristics.
Soil Profiles
The sequence of soil horizons down to the bedrock.
Erosion
The transportation of regolith from one place to another and abrasion of the Earth's surface by materials being transported.
Mass Wasting
Downslope movement of regolith and/or bedrock masses due to the pull of gravity.
Saltation
Sediments moving by bouncing off of each other.
Erosion by water
Sediments carried in the suspended load(small) and the bed load(large).
Erosion by wind
Wind cannot move sediments that are as large as water can carry. Sorts sediment better than water.
Erosion by ice
sediment carried by glaciers and carves groves in the bedrock.
Falls
A sudden vertical drop of rock fragments and debris.
Slide
Rapid displacement of mass movement down a planar slope.
Slump
a rotational movement of rock.
Flow
Any mass wasting process that involves flowing of mass regolith.
Creep
Imperceptibly slow downslope flow of regolith.
Frost Heaving
Uplift of surface rock and regolith as a result of the freezing of subsurface water to form ice.
Sedimentary Rocks
produced from weathering products of pre-existing rocks or accumulated biological matter.
Detrital
rocks produced from rock fragments.
Chemical
rocks produced by precipitation of dissolved ions in water.
Organic
rocks produced by accumulation of biological debris, such as swamps or bogs.
Sediment
loose, solid particles originating from weathering and erosion of pre-existing rocks.
Transportation
Movement of sediment away from its source. Typically by water, wind, or ice.
Deposition
Settling and coming to rest of transported material.
Preservation
Sediment must be preserved, as by burial with additional sediments, in order to become and sedimentary rock.
Lithification
The processes of changing sediment to sedimentary rock.
Clastic Rocks
Classified by grain size and shape. Ex. Breccia, Conglomerate, Sandstone, and Shale.
Conglomerate
Round grains
Breccia
Angular grains
Sandstone
sand-sized grains
Shale
smaller than sand-sized grains
Evaporates
Chemical sediments that form when water evaporates.
Precipitates
Iron-rich siliceous sediments precipitated out of anoxic sea water more than 18 billion years ago.
Biogenic rocks
Limestones, Chert, Peat, and Coal
Stream Sediment
Carry a lot of sediments in every size of clast. Deposits can be well to poorly sorted, to graded beds.
Lake Sediment
Generally well-sorted sediments or graded beds in deltas that form when streams flow into a lake.
Glacial Sediment
generally poorly-sorted and angular.
Eolian Sediments
Wind blown sediments. Best sorted sediments because only smallest grains are carried by normal winds.
Metamorphism
The mineralogical, chemical, and structural adjustments of solid rocks to physical and chemical conditions at depths below the region of sedimentation and diagenesis.
Foliation
the alignment of minerals in metamorphic rocks.
Slaty cleavage
The quality that causes low grade metamorphic rocks to part or split along a plain.
Schistocity
When the oriented mica grains are large enough to be seen with the naked eye.
Effects of Temperature
As temp increases the minerals that grow are different.
Contact Metamorphism
occurs when rocks are heated and chemically changed by the intrusion of a body of hot magma.
Shock Metamorphism
occurs in a shock such as an asteroid.
Burial Metamorphism
sedimentary rocks that are deeply buried (>10 km) in trenches are altered.
Regional Metamorphism
of an extensive area of the crust as a result of the stresses and high temps associated with plate convergence, collision, and subduction.
Index Minerals
minerals that form at specific pressures and temperatures.
Isograds
lines on maps of occurence of index mineral assemblages.
Foliated Rocks
Slate, Phyllite, Schist and Gneiss
Slightly Foliated
Amphibolite, Granulite, Blueschist, Eclogite
Non-foliated
Marble and Quartzite