zones of the earth
core
mantle & asthenosphere
crust (continental and oceanic)
what is the earth's crust broken into?
tectonic plates
what to tectonic plates float on?
the asthenosphere
who discovered continental drift?
Alfred Wegener
continental drift
the gradual movement of the continents across the earth's surface through geological time
why does continental drift occur?
b/c of plate tectonics, which move because the interior of the earth isn't heated equally (convection currents)
what drives the movement of tectonic plates?
convection currents
convergent plate boundary
can result in the creation of mountains, island arcs, earthquakes, tsunamis, deep sea trenches, and volcanoes
divergent plate boundaries
can result in seafloor spreading, rift valleys, and earthquakes
transform plate boundaries
can result in earthquakes
p (earthquakes)
moving across
s wave (earthquakes)
up and down
more dangerous
weathering
the process of wearing or being worn by long exposure to the atmosphere
mass wasting
the movement of rock or soil down slopes under the force of gravity
erosion
the geological process in which earthen materials are worn away and transported by natural forces such as wind or water
physical weathering
mechanical breakdown of rocks and minerals
chemical weathering
chemical breakdown of rocks and minerals
release essential nutrients from rocks
types of chemical weathering
dissolution
oxidation
hydrolysis
anthropogenic
types of physical weathering
frost wedging
unloading
thermal expansion
biological activity
plant root wedging
frost wedging
a form of physical weathering that breaks down rocks through the freezing and thawing process
ex. boulders and mountains in cold climates with large cracks
unloading
the removal of great weights of rock or ice that lie on the surface
ex. the domes in Yosemite
thermal expansion
the tendency of matter to change in shape, volume, and area in response to a change in temperature
ex. railway tracks in the summer
biological activity
when plants break up rocks with roots
ex. tree roots breaking up rocks
plant root wedging
fractures in rocks are enlarged by the growth of plant roots
ex. tree roots making cracks in rocks larger
dissolution
when water comes into contact with rocks and dissolves the minerals that make up that rock into individual elements
ex. dissolving a teaspoon of salt into water
oxidation
when oxygen reacts with other elements and electrons are transferred between two elements
ex. the reaction between magnesium and oxygen that forms magnesium oxide
hydrolysis
a new solution is formed as chemicals in rock interact with water
ex. sodium minerals react with water to form a saltwater solution
anthropogenic
weathering as a result of human action
ex. burning of fossil fuels
why is surface area so important to the weathering process?
smaller pieces have more surface area for water and gasses to react with the rock. therefore, smaller rocks undergo chemical weathering faster than large rocks
joints
a type of extension fracture formed by movement of the rock in a direction perpendicular to the plane of fracture
why are joints so important to the process of weathering?
they effectively cut large blocks of rock into smaller one thus increasing the surface area where chemical reactions can take place
how do caves and sinkholes form?
water dissolves minerals in the rock, leaving residue and open spaces within the rock
layers of soil horizons
humus
organic component of soil
eluviation
the transportation of dissolved or suspended materials by the movement of water (rain)
leaching
draining a soluble chemical from the soil
solum
layers that have gone through soil formation
o horizon (organic)
decomposed organic material
also called humus
most pronounced in forests
a horizon (topsoil)
surface soil/topsoil
organic mixed with mineral material
most biological activity
e horizion
minerals
zone of leeching
b horizon (subsoil)
mineral material - zone of accumulation of metals and nutrients
c horizon
least weathered
similar to parent material
soil layer acronym
Only After Eating is Beall Cheerful
what make up the components of soil?
sand, silt, clay
describe how to use a soil texture chart
physical properties of soil
permeability
permeability
the rate at which water can flow through a substance
porosity
the pore space in soil between mineral particles filled with either air or water
chemical properties of soil
CEC
base saturation
base saturation
proportion of bases to acids in soil expressed as a percentage
CEC
Cation Exchange Capacity
nutrient holding capacity
clay, acidic pH, organic material
biological properties of soil
fungi, bacteria, protozoans = 80-90%
rodents, earthworms, snails, slugs (detritivores) - mixing, breakdown of material
nitrogen fixing bacteria
why is the biological part of soil so important for soil health?
because biologically active soils increase organic mater which causes their capacity to hold water to increase