Unit 1 + 2: Earth Systems and Plate Boundaries

The aspects of environmentalism

1. Earth is finite

2. Exponential Population Growth

3. Sustainability & Resource Consumption

4. Systems Approach

5. Equilibrium

6. Threshold

7. Earth Impact => Humans Hazards = Hazards

8. Earth History & perspective

9. Solutions rely on Science, Politics, Values

Sustainability

the practice of using resources in a way that makes them available for the future

Systems

a complex entity that consists of many components, and there are meaningful relations between them

Lithosphere

crust and outer mantle

Atmosphere

gaseous

Hydrosphere

water

Biosphere

living things

Cryosphere

glacial ice and permafrost

Airshed

an air point that is constantly being pushed by frequent, typical wind patterns and contributes to the air quality of an air system

Topography

the configuration of the surface of the land

Topographic boundaries

the natural drain-off points upon hilltops that separate the adjacent watersheds through splitting water runoff

Topographic map

a two-dimensional representation of the three-dimensional land surface

Gradient

the slope of the land or river

Equilibrium

there can exist a balance among the components of a system

Threshold

the tipping point/limit of Equilibrium; the boundary between equilibrium and disequilibrium

Braid rivers

high-energy, wide, and shallow rivers from their steep slopes and transport significant coarse material like sediment (sand and gravel mixture). When the sediment gets trapped, the flow decreases, causing vegetation to change its growth shape which results in the river becoming deep and narrow

Systems Approach

using components of the Earth System to solve the above problems

Interactions between the Atmosphere and Lithosphere systems

Atmospheric CO2 increases due to the living burning fossil fuels

Interactions between the Atmosphere and Hydrosphere systems

Atmospheric CO2 increases due to the ocean's acidification from absorbing its CO2 and as a result releases carbonic acid causing plants to decay

Epicenter

geographic location of the starting point of an earthquake on the Earth's surface

Focus

exact location in the Earth's crust where the earthquake occurs

Collision

involves the oceanic plate dissolving into the mantle

Subduction

when a plate descends into the mantle

Overriding plate

the plate at a subduction zone that overrides the downgoing plate

Distribution of volcanoes

one set of volcanoes occurs when magma from the mantle rises to the surface which creates new crust

Subduction zones

places where oceanic plates are pushed down into the upper mantle. Found drawn along the axis of the oceanic trench

Subduction zone associations

deep earthquakes beneath the overriding plate and a volcanic arc

Collision zones

when two continental plates collide. Neither plate is forced under the other, and so both are forced up and form fold mountains.

Collision zone associations

very high topography on the overriding plate and a foreland basin.

Seismic imaging

when supercomputers create an image of the Earth's subsurface by analyzing reflections of acoustic waves recorded at the surface.

Seafloor data

Vine and Matthews paleomagnetic strips that are visible in the seafloor and show the age of the plate due to one of the alternating indications of polarity eras

Spreading center

formed when two tectonic plates move away from each other and the magma from the mantle upwells to fill that space and erupts at the boundary to form new crust.

Interior Structure of the Earth's classification

its composition (density) and the physical state of the material

Geosphere

composed of the mantle (lithosphere, asthenosphere, and mesosphere) and the outer and inner core

Magnetosphere

Earth's magnetic field

Magnetic field purposes

1. deflecting solar wind and harmful ions and radiation

2. aids navigation used by humans and migratory animals

3. provides heat flow in the mantle thereby transferring heat from the surface

Divergent boundary

extensional plate boundary (spreading centers + rifts)

Convergent boundary

collisional/compressional plate boundary (mountains)

O-O convergent

subduction, volcanism, lahars (volcanic debris), tsunami (triggered by submarine landslide or underwater earthquake)

O-C convergent

Seismicity, Explosive Volcanism, Lahars (mudflows), cascades

C-C convergent

no subduction! No volcanoes, suture zone, deformation (folding and faulting)

Transform boundary

a shear boundary created when two plates move alongside each other. associated with shallow earthquakes.

Oceanic crust

the crust created as magma rises to fill the gap between diverging tectonic plates and is consumed in subduction zones; composed of mafic rock

Mafic rock

rocks that have higher concentrations of Fe, Ca, and Mg with typically dark color

Mafic rock examples

basalt, troctolite, and gabbro

Basalt density

3 g/cm3

Continental crust

crust formed due to cooling of magma after two plates collide with each other when one plate moves down another. The plate moving down gets heated tremendously due to the internal heat of the Earth and melts this way it gets destroyed; consists of felsic rock

Felsic rock

rocks that are rich in elements such as Al, K, SiO2, and Na with typically light color

Felsic rock examples

granite, rhyolite, feldspar, quartz, and pyroxenes

Granite density

2.7 g/cm3

Benioff Zone

A line of earthquake activity along the upper portion of a sinking plate, as it scrapes past the opposing plate, in a subduction zone. it marks the position of a subductive plate (solid oceanic)

Hotspot

a fixed place in the Earth's mantle where magma rises, causing volcanoes to form on the plate above them

Lahar

a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water

Ultramafic rock

An igneous rock consisting primarily of mafic minerals and containing an extremely low silica composition yet high in Fe and Mg. (olivine and pyroxene)

Asthenosphere

The semi-molten / plastic portion of the upper mantle directly below the lithosphere