AP Environmental 4.1 - 4.3

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