APES Unit 7

DISGUSTING

The elements and minerals that were present when the planet formed are all we have today (t/f)

True

Core

* The innermost zone of Earth’s interior
* composed mostly of iron and nickel
* includes a liquid outer layer and a solid inner layer

Mantle

* above core
* containing magma (molten rock)

Asthenosphere

* the layer of Earth located in the outer part of the mantle
* composed of semi-molten rock

Lithosphere

* the outermost layer of Earth
* include mantle and crust
* made up of several large and numerous smaller plates → overlie the convection cells within the asthenosphere

Crust

* the chemically distinct outermost layer of the lithosphere
* a thin layer of soil on top allows life to exist
* crust + overlying soil → provide most chemical elements that make up life

Earth layers overlap

Ex. the lowest part of the lithosphere is the uppermost portion of the mantle

Hot spots

a place where molten material from Earth’s mantle reaches the lithosphere

High temp of Earth’s outer core and mantle is the result of

radioactive decay of isotopes of elements, which release heat

Plate tectonics

the theory that the lithosphere of Earth is divided into plates, most of which are in constant motion

Tectonic cycle

the sum of the processes that build up and break down the lithosphere

Crust of oceanic plates: rich in ___

iron

Crust of continental plates: rich in ___

silicon dioxide (less dense than iron)

new vs old lithosphere

New lithosphere is added at spreading zones; older lithosphere is recycled into the mantle at subduction zones

Oceanic and continental plates movements are driven by

convection cells (driven by heat from the core) in Earth’s mantle

Seafloor spreading

convection in the mantle → seafloor spreading

* the formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side
* create new lithosphere
* bring important elements to surface

subduction

the process of one crustal plate passing under another

consequences of plate movement

Plates move → continent drift → climate change & geographic barriers formed or removed → species evolved and adapted or went extinct

Volcanoes formed at/in

* hotspots
* seafloor spreading
* subduction
* divergence

Divergent plate boundary

* An area beneath the ocean where tectonic plates move away from each other
* seafloor spreading

Convergent plate boundary

* An area where plates move toward one another and collide


* The plates generate lot pressure as they push against one another

Transform fault boundary

* An area where tectonic plates move sideways past each other

Fault

a fracture in rock caused by a movement of Earth’s crust

Seismic activity

the frequency and intensity of earthquakes experienced over time

fault zone (aka areas of high seismic activity)

* a large expanse of rock where a fault has occurred
* form in the brittle upper lithosphere where two plates meet or slide past one another

Two continental plates meet & both plate margins lifted →

mid-continental mountain range

Earthquake

* the sudden movement of Earth’s crust caused by a release of potential energy along a geologic fault and usually causing a vibration or trembling at Earth’s surface
* occur when the rocks of the lithosphere rupture unexpectedly along a fault

Epicenter

the exact point on the surface of Earth directly above the location where rock ruptures during an earthquake

Ring of Fire

Richter scale

a scale that measures the largest ground movement occurs during an earthquake (logarithmic)

Impacts of moderate earthquakes (5.0-5.9)

collapsed structures, fires, contaminated water supplies, ruptured dams, deaths

Tsunami

a series of waves in the ocean caused by seismic activity or an undersea volcano

impacts of volcanoes

deaths, habitat destruction and alteration, air pollution, etc

Rock cycle

the geologic cycle governing the constant formation, alteration, and destruction of rock material that results from tectonics, weathering, and erosion, among other processes

Slowest of all of Earth’s cycles

Rock cycle

Rocks form when ___

magma from Earth’s interior reaches the surface, cools, and hardens

3 ways rocks at surface can be formed: Directly from molten magma →

igneous rocks

3 ways rocks at surface can be formed: by compression of sediments →

sedimentary rocks

3 way rocks at surface can be formed: By exposure of rocks and other Earth minerals to high temps and pressures →

metamorphic rocks

intrusive igneous rocks

form when magma rises up and cools in a place underground

extrusive igneous rock

form when magma cools above the surface of Earth

Cools rapidly → no large mineral individual crystals → fine-grained, smooth types of rock

Formation of igneous rock brings surface ___

rare elements and metals

Fractures

a crack that occurs in rock as it cools

what rocks are fossils found?

sedimentary rocks

what rocks are important building materials?

metamorphic rocks

Which layer of Earth is composed primarily of iron and nickel?

the core

the Hawaiian Islands were formed at ___

hot spot

weathering

occurs when rock is exposed to air, water, certain chemical compounds, or biological agents such as plant roots, lichens, and burrowing animals

Physical weathering

* the mechanical breakdown of rocks and minerals
* can be caused by water, wind, or variation in temp, biological agents, burrowing animals
* expose more surface area and makes rock more vulnerable to further degradation
* increase the rate of chemical weathering

Chemical weathering

* release essential nutrients from rocks
* breakdown of rocks and minerals by chemical reactions, the dissolving of chemical elements from rocks, or both
* occurs most rapidly on primary minerals

example of chemical weathering

water that contains carbonic acid wears away limestone, sometimes forming cave systems

Chemical weathering sometimes are result of human activities

acid precipitation

* Acid rain falls on soil → promotes chemical weathering of certain minerals in the soil → leaching of soil

weathering can reduce atmospheric CO2 concentrations (t/f)

true

Erosion

the physical removal of rock fragments from a landscape or ecosystem

what can create/accelerate erosion problems

poor land use practices

* deforestation
* overgrazing
* unmanaged construction activity
* road building

soil functions

* medium for plant growth
* breaks down organic material and recycles nutrients
* habitat for organisms
* filter water

soil formation

result of physical and chemical weathering of rocks and gradual accumulation of detritus from the biosphere

5 factors simultaneously determine the properties of soil

parent material, climate, topography, organisms, time

parent material

the underlying rock material from which the inorganic components of a soil are derived

topography

the surface slope and arrangement of a landscape

how do plants speed chemical weathering

Plants remove nutrients from soil & excrete organic acids that speed chemical weathering

overuse land for agriculture, forestry, and other activities →

soil degradation

compaction of soil by machines, humans, and livestock →

alter properties and reduce ability to retain moisture, increase erosion

intensive agricultural use and irrigation →

deplete soil nutrients

horizon

a horizontal layer in a soil defined by distinctive physical features such as texture and color

* vary depending on climate, vegetation, parent material

soil horizon orders

O, A, E, B, C

O horizon

* composed of organic detritus in various stages of decomposition
* most pronounced in forest soils and some grasslands

Humus

the most fully decomposed organic matter in the lowest section of the O horizon

A horizon (aka topsoil)

a zone of organic material and minerals that have been mixed together

E horizon

a zone of leaching, or eluviation, found in some acidic soils under the O horizon, or less often, the A horizon

B horizon

composed primarily of mineral material with very little organic matter, including humus

C horizon

* the least-weathered soil horizon
* similar to the parent material

texture: soil consist of a mixture of ___

clay, silt, sand

soil texture particles big to small:

sand > silt > clay

the permeability of soil depends on it ___

texture

best agricultural soil:

mixture of sand and clay that would be characterized as loam (40% sand, 40% silt, 20% clay)

what particles contribute to most chemical properties of soil?

clay particles

cation exchange capacity (CEC)

the ability of a particular soil to absorb and release cations (positively charged mineral ions)

soils with high CECs

provide essential cations to plants → desirable for agriculture

soil acids

detrimental to plant nutrition (bad)

soil bases

promote plant growth

essential for plant nutrition (except sodium)

Base saturation

the proportion of soil bases to soil acids, expressed as a percentage

soil with high CECs and high base saturation → support ___ productivity

high

crustal abundance

the average concentration of an element in Earth’s crust

most abundant elements in the crust

oxygen, silicon, aluminum, iron

ores

concentrated accumulation of minerals from which economically valuable materials can be extracted (ex. salt and sand)

how do ores form

* form when magma contact with water
* form after the deposition of igneous rock
* formed by intense chemical weathering in tropical regions (ex. bauxite)

metal

an element with properties that allow it to conduct electricity and heat energy, and to perform other important functions

reserve

the known quantity of a resource that can be economically recovered

Surface mining includes:

strip mining, open-pit mining, mountaintop removal, placer mining

strip mining

* the removal of strips of soil and rock to expose ore
* often the case for deposits of sedimentary materials (coal, sand)

mine tailing

unwanted waste material created during mining including mineral and other residues that are left behind after the desired metal or ore is removed

open-pit mining

create a large visible pit or hole in the ground

ex. copper mines

one of the largest open-pit mines in the world

Kennecott Bingham Canyon mine

mountaintop removal

entire top of a mountain is removed with explosives

subsurface mining is safer than mountaintop removal (t/f)

false

placer mining

the process of looking for minerals, metals, and precious stones in river sediments

* use river water to separate heavier items from lighter items

subsurface mining

* used when the desired resource is more than 100m below the Earth surface
* ex. coal, diamonds, gold

mining impacts: road construction →

soil erosion, waterway damage, habitat fragmentation

mining impacts: mine tailings →

rainfall leads to contamination of water and land with acids and metals