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Define weathering
The chemical or physical breakdown of rocks
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What is CHEMICAL weathering?
The breakdown of rock through a change in chemical or mineral composition
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What is PHYSICAL weathering?
The physical breakdown of rocks into smaller pieces.
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Name the 3 most common chemical weathering agents.
- water (causes hydration)
- oxygen (causes oxidation)
- carbon dioxide (causes carbonation)
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What is Oxidation?
oxygen combines with a material and weakens it. ex) rusting (oxygen combines with metal and reacts with surface to make rust)
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What is Hydration?
Water combines with a material and either dissolves it (like a salt) or speeds up the reaction (like increasing the speed of rusting)
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What is Carbonation?
- Carbon dioxide combines with water to make carbonic acid.
- Carbonic acid easily dissolves certain rocks like limestone and marble.
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Name the 5 types of Physical weathering.
- Frost Action
- Plant Action
- Abrupt Temperature Change
- Abrasion
- Pressure Unloading
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Describe Frost Action
- Water gets trapped in cracks of a rock, freezes, EXPANDS, and widens the crack.
- Note: the climate must be one that goes above and below the freezing point.
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What is Plant Action?
Tiny plant roots get into a rock crack, grow larger, and widen the crack, or uplift a sidewalk, and/ or crack it.
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What does "abrupt temperature change" mean and cause ?
Temperatures change quickly, and cause rapid expansion and contraction of rocks, which breaks them.
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Describe Abrasion of rocks.
Abrasion is grinding of a rock surface on something else (another rock, ice) usually as it is being dragged along by a river, or glacier, or wind.
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Name the 4 (or as many as you can) major factors the affect the rate and type of weathering a rock experiences.
(Why do some rocks weather quickly, and some weather very slowly?)
- 1. Exposure (to the atmosphere)
- 2. Size of the rock (particle size)
- 3. Mineral composition (what it is made of)
- 4. Climate !!!!!! the rock is in.
*** be ready to explain each of these :)
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Finish this sentence:
The closer a rock is to the surface, the ___________________ it will weather.
(faster or slower)
And answer why ?
Faster ! ( the more exposure to the atmosphere-rain,snow, temp. changes- it has, the faster the rock weathers)
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If you start with 2 rocks, exactly the same size, weight, and composition and smash one into tiny pieces, then leave them both outside for 1000 years, which one weathers faster ? and why?
the one that is in tiny pieces because it has more total surface area being exposed to weathering factors.
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What is the rule about mineral composition and rate of weathering of a rock?
The softer a mineral is, that makes up a rock, the faster the rock will weather.
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Describe a climate (temp. and moisture type) that would cause the MOST weathering-
and explain why !
warm and moist climates cause the most weathering because heat is a catalyst and water is a catalyst (they speed up reactions)
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What 2 things make up soil?
rock particles and humus (dead, decaying plants and animals)
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Describe transported AND residual soil and
state which one is much more common.
- transported soil-made of sediments that were transported (moved)
- residual soil-made of sediments that match the bedrock below (sediments have not moved (eroded))
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What is the MOST important factor in determining soil type?
CLIMATE !!
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Define EROSION
the carrying away (moving) of sediments by erosional agents (like wind, water, ice)
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WHat does erosion do to the earth's surface ?
shapes and lowers the land
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List the SIX erosional agents and state which one moves the most sediment on earth.
gravity, running water, wind, glaciers, waves and currents, animals -----running water moves the most sediment.
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What is the driving force behind all other erosional agents?
gravity
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Soil creep, debris flow, mud flow, and rock fall are all examples of what erosional agent in action?
gravity
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Name the 2 categories of streams and describe them
- permanent stream: always flows: stream bed is below the water table always
- intermittent stream: sometimes dries up: stream bed may be above the water table
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What is the smallest possible sediment and how is it carried?
an ion ! an ion is carried "in solution" (which means it is dissolved in water)
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What are the smallest clay particles called? and how are they carried in a stream?
- Colloids
- They are "in suspension" in water.
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How do sand, cobbles pebbles and boulders move in a stream?
bouncing, rolling or sliding on the stream bed
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The land drained by a stream system is called what ? And what is the imaginary line that surrounds it called?
watershed or drainage basin and the line is called the drainage divide
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What shape valley does a stream carve?
V-shape
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Name and explain the 3 things that determine stream velocity (speed)
- slope (greater = faster water)
- discharge (volume) : greater discharge=faster water
- channel shape:more water touching land = slower water
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where is the fastest water in a straight stream? why?
- center, a little below the surface
- reason: least friction
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on a bend in a stream where is the fastest water ?
where is the most erosion?
-on the outside of the turn
-on the outside of the turn
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on a stream bend, where is the most deposition? why?
on the inside of the turn - slowest
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go to page 6 ESRT
If stream is going 100 cm/sec, what is the biggest sediment it can carry ?
pebbles
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What are the 3 stages of a stream and which one has waterfalls and rapids?
Name another feature of a youthful stream.
- youthful,mature, old age
- -youthful
- other: sharp v-shaped valleys, fast water, alot of carving/downcutting, no deposition
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What stage has meanders?
What stage has oxbow lakes?
-mature stage
-old age stage
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What erosional agent causes deflation and sandblasting? and what are these processes?
WIND sand is removed by wind, lowering the surface. sand is blasted against rocks, carving out the lower parts., (making a hoodoo sometimes)
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Name the 2 types of glaciers
alpine (valley)
continental
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name 3 erosional features of an alpine glacier
and be able to describe/recognize them
horn , cirque, hanging valley, arete , fan-shaped land delta
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Name the continental glacial erosional features created in New York state
the Great Lakes, the Finger Lakes, (and parallel grooves and scratches on the bedrock all over the state)
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What are breaking waves called and what do they deposit ?
surf : they deposit sand which can become a sandbar
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what is the ocean water moving parallel to the shore called?
a longshore current
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What does water do to the size and shape of rocks? (think of the rock-shaking lab)
sediments are made rounder, smoother, smaller
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Name 3 things humans have done to increase erosion of the land
road building, mining, deforestation, over grazing, poor farming methods, construction of buildings
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name 3 things humans have done to prevent erosion or reclaim the land
replanting logged forests, restore coastal vegetation, limit grazing, no-till farming, contour plowing, rip-rap on hillsides
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