APES Soil & Geology Test – Flashcards
Unlock all answers in this set
Unlock answersquestion
4 parts of soil
answer
- mineral particles (45%) - organic matter (5%) - water (25%) - air (25%)
question
Why is soil important?
answer
- shelter, food and water for microorganisms - plants use it for nutrients and water, a place to grow - serves as a natural filter for water
question
Physical Weathering
answer
sheet erosion (wind/water peel layers of soil in sheets), rill erosion (small channels are carved out by water), gully erosion (extreme rill erosion)
question
Chemical Weathering
answer
plant roots/animal cells go through cellular respiration and the CO2 diffuses into the soil, reacting with water which forms carbonic acid and this eats away at the soil/rock
question
Soil: texture
answer
the amount of sand, silt and clay a soil contains; gritty (has a lot of sand), sticky (has a lot of clay), silt (smooth like flour)
question
Soil: friability
answer
the ability of soil to be reduced to smaller pieces with little effort, especially by rubbing
question
Soil: porosity
answer
the amount of air/water a certain volume of soil can hold
question
Soil: permeability
answer
the rate at which air and water can move from upper to lower soil layers
question
Soil: shrink-swell potential
answer
some soils (clay) swell when water gets in them, then crack when they dry out
question
Soil: pH
answer
normal pH of soils is 4.0-8.0 (pygmy forest has acidic soil and death valley has basic soil)
question
Soil: slope
answer
steep slopes have very little soil because of gravity, runoff from precipitation also erodes the soil on slopes
question
Soil: depth
answer
some soils are a few inches deep until you can hit rock, others are up to 3 feet deep
question
Soil: color
answer
dark soil is rich w/ lots of organic matter, light soil has very little organic matter
question
O-horizon
answer
Organic Layer, uppermost layer filled with plant litter = lots of nutrients
question
A-horizon
answer
Topsoil, dark/rich in organic matter and humus, granular texture and a slight loss in nutrients due to leaching of nutrients to lower levels
question
B-horizon
answer
Subsoil, light colored, nutrients and minerals that have been leached accumulate here, rich in iron, aluminum and clay
question
C-horizon
answer
Parent Material, weathered pieces of rock and other parent material, saturated w/ ground water
question
Importance of erosion
answer
- it reduces the fertility of soil, not a good thing - over 6 tons of soil is eroded from the US (caused by removal of plants, rising sea levels, acid rain, extreme weather due to climate change, agriculture techniques)
question
Methods to control erosion
answer
1985 Food Security Act (Farm Act): called for replanting eroded land and repairing it, farmers will get a subsidy for following the law
question
Dangers of the Pacific Ring of Fire
answer
the plates are spreading (divergent boundary) and moving towards each other (convergent boundary), which makes it easy for magma to come on to the surface and form volcanoes, convergent boundaries also form earthquakes when the plates get stuck on each other and then fall apart violently
question
Why fossils in sedimentary rock?
answer
Sedimentary rock is formed by smaller pieces of rock and sand being pressed together. A plant or animal can be stuck inside these layers and compressed within the rock, making a fossil. Other kinds of rock are formed by heat and melting, so a fossil would not be able to remain in that kind of rock.
question
Sedimentary Rock
answer
formed by layers/pieces of rock or sand being compressed together under lots of pressure (ex: conglomerate, breccia, non-clastic)
question
Metamorphic Rock
answer
formed when either sedimentary or igneous rock is put under large amounts of heat and pressure, so that it turns into a different kind of rock (ex: dynamic, contact)
question
Igneous Rock
answer
formed by solidified magma (ex: intrusive or extrusive)
question
Layers of the earth
answer
core (solid inner core and a molten outer core), mantel or asthenosphere (molten magma), crust (tectonic plates on top of molten magma)
question
P waves
answer
travel through anything, smaller and faster, compression & expansion happens horizontally
question
S waves
answer
only travel through liquids, larger and slower, vertical movement
question
Convection Currents
answer
inside of the mantel, heat rises and cool air/magma sinks
question
saltation
answer
when one particle hits another, increases erosion
question
suspension
answer
airborne soil
question
surface creep
answer
surface creeping slowly on top of the crust (a landslide is a very fast surface creep)
question
1985 Food Security Act
answer
known as the Farm Act, called for replanting eroded land and repairing it, farmers will get a subsidy for following the law
question
leaching
answer
dissolving minerals/matter in upper layers being carried down to lower layers
