Earth Science Topic 9

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weathering: the chemical and physical breakdown of rocks at or near the earths surface
when does weathering occur?: when rocks are exposed to air, water, and the actions of living things
what is the difference between weathering and erosion?: weathering breaks rocks down without moving them, but erosion moves them
what does weathering result in?: residual soil in the same spot where the rock was
how much of the worlds soil is residual: 5%
what are examples of ways erosion can occur?: rivers, wind, glaciers, and gravity from landslides
what is the soil from erosion called?: transported soil
how much of earths soil is transported?: 95%
chemical weathering: the breakdown of rock through a change in mineral or chemical composition
2 examples of chemical weathering: 1. oxidation rusting
2. effect of water on minerals
physical weathering: breaks down rocks of the same material
when does physical weathering occur?: when frost action, plant root growth, or abrupt temperature changes causes rocks to crack apart
4 agents of physical weathering: 1. frostation
2. thermal expansion
3. biologic
4. pressure unloading
frostation: water expands when it freezes
thermal expansion: heating and cooling causes rocks to crack
pressure unloading: removing surface layers off the rock-rock comes apart
abrasion: process where rock particles grind against another rock--physical weathering
what characteristic of rocks from river beds and beaches is caused by abrasion?: rounded shape
what factors affect the rate and type of weathering?: exposure, particle size, mineral composition, and climate
in what ways does exposure affect weathing?: rate and type of weathering
how does the distance of a rock to earths surface affect weathering?: the closer a rock is to earths surface, the faster it will weather
how does particle size affect weathering?: when particles are smaller, the total surface area per unite volume exposed to weathering is greater, so the rate of weathering is faster
how does mineral composition affect the rate of weathering?: different minerals have different physical and chemical properties and weather at different rates
where is chemical weathering most pronounced?: in warm, moist climates
affect of temp. and humidity on chemical weathering: the higher the average temp and humidity, the more rapid chemical weathering
what is the most common form of weathering in cold climates?: frost action
where is frost action especially intence?: in moist climate with temp variations that lead to repeated cycles of freezing and thawing
what are soil layers called?: horizons
how can soil be transported into an area from another place?: wind, moving water, and moving ice of a glacier
how does soil develop in bedrock?: originally, there is unweathered bedrock at the surace. soil development, by way of weathering, starts at earths surface and gradually progresses downwartd over time to produce soil layers.
why is water a major agent of chemical weathering?: it dissolves many of the minerals that make up rocks
why are a variety of soil types found in new york states?: becuase areas of the state differ
what is the chemical composition of a soil formed in a certain area from the bedrock beneath determined by?: minerals in the bedrock beneath the soil and the climate of the area
new york soils are most likely composed of rock particles that have been..: transported by glaciers or water
what does erosion do to earths surface over time?: shapes and lowers it
4 erosional agents: 1. rivers or running water
2. glaciers
3. gravity
4. wind
characteristics of rivers or running water: rounded particles
how do the 3 size particles change erosion?: 1. large particles are rolled and bounced
2. small-fine particles called "colloids" are in suspension
3. ions dissolve-solution
results of glacier erosion: -unsorted deposited
-scratched rock
-polished rock
-parallel groove
-u-shaped valley
gravity characteristics: rock becomes angular
rock deposits
wind agent: carries fine particles
what is river velocity determined by?: 1. slope
2. volume of discharge
characteristics of young river: flows fast
goes straight
water falls, rapids
carves v-shape valley
river bed: bottom of river
river banks: sides of river
in a straight river, where does it flow fastest?: in the middle
why?: there is no friction with air, sides, or bottom
where is teh most erosion on the straight river?: directly below the middle point
meanders: bends in the river
where is the river the fastest when it curves?: the outside of the curve
where is it the slowest?: the inside of the curve
where is erosion dominant in a curved river?: on the outside curve
where is deposition dominant?: on the inside curvve
whhat side of the side view is shaded in?: the inside curve side
levees: small deposits that build up on the ride of a river
base level: sea level
characteristics of old age river?: close to base level
at base level-river slow
flood plain: flat land on sides of old river
water shed: all areas that feed one major river system
how does an ox bow lake form?: the river curves, then goes straight again and there is a cutoff
delta: forms at the mouth of a river from sediments deposited over time from the ever-shifting channel at the streams mouth
deflation: removal of the small top loose particles
sandblasting: wind causes sand to hit rocks and that will erode those rocks down
where do glacirs move fastest?: in the middle
what kind of valleys do glaciers carve out?: u-shaped
what are glaciers erosional features?: groove,s striations, unsorted rock
what moves at the same speed as a river?: dissolved salts (ions)
how do things carried by a river move in relation to the river?: move slower
what happens when an erosional system loses kinetic energy?: it will drop the sediments its carrying
horizonal sorting: as a river slows down, it drops off the largest particles, then the smallest
when there is maximum KE there is max...: erosion

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