Geoscience

Plate tectionics
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Alfred Wegner
German Meteorologist who proposed the theory of coninental drift (the idea that the continents were moving)
continental drift
The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations
fossil
Preserved remains or traces of ancient organisms.
pangea
According to theory this was a "supercontinent" that contained all of Earth's land about 225 million years ag.
theory of plate tectonics
Earth's lithosphere is divided into tectonic plates that move around on top of the asthenosphere
faults
A fracture in the crust along which rock moves forward and backward, up and down, or from side to side. Fault zones are often found at plate boundaries
transform boundaries
a boundary where two plates slide past one another without creating or destroying lithosphere
divergent boundaries
tectonic plates spreading apart, new crust being formed (ex. mid-ocean ridges, rift valleys).
convergent boundaries
Area where two tectonic plates move toward one another and collide
deep ocean trench
where the ocean floor plunges into deep underwater canyons, subducting back into the mantle: converging boundaries
subduction
Process in which one plate moves under another plate, and into the mantle. Takes place at a convergent boundary.
convection currents
Convection currents are the flow that is created due to this heat transfer. As a fluid is heated, it becomes less dense and rises. The cooler fluid (at the surface) is denser and sinks causing a current.
sea floor spreading
The process by which molten material adds new oceanic crust to the ocean floor
mid -ocean ridge
the place where plates of the Earth's crust along the ocean floor are being split apart and molten rock pushes up to form new ocean floor and a mountain range
direct evidence
Evidence that comes from you measurements, tests, or observations: example, rock samples
indirect evidence
Evidence that does not involve direct observation such as seismic waves to determine facts about the Earth's interior
sonar
A device that bounces sound waves off underwater objects and then records the echoes of these sound waves.
magnetic striping
The symmetrical pattern of alternating normal and reversed magnetic polarities found in the seafloor on either side of the spreading center.
rift valley
Caused by divergent plates pulling apart at areas above sea level. The land between the two diverging plates sink into a valley
lithosphere
the solid, outer layer of the Earth that consists of the crust and the rigid upper part of the mantle
asthenosphere
The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
continental crust
Granitic part of the Earth's crust that makes up the continents, lower density
oceanic crust
Earths crust located under the ocean that is usually thinner but more dense than continental crust
granite
A usually light colored igneous rock that is found in continental crust: coarse grained: less dense
basalt
A dark dense igneous rock with a fine texture found in oceanic crust
seismic waves
Energy released from an earthquake that travels in the form of waves out from the focus in all directions
p waves
Compressional. Move the fastest through all materials. Arrive first at seismograph: compresses and expands the ground. Will travel through any material
s waves
Seismic Body Waves that produce a crossways or shearing motion in rock particles. Cannot travel through liquid! This shows us that the earth's interior (shadow zone) is full of liquid rock.
surface waves
are the slowest and largest of the seismic waves and cause most of the destruction during an earthquake
outer core
A layer of molten metal, mainly nickel and iron, that surrounds Earth's inner core.
inner core
Solid Iron and Nickel due to the enormous pressure it is under from all the layers above it!
radiation
Energy that is radiated or transmitted in the form of rays or waves or particles: as in from the sun
convection
Process by which, in a fluid being heated, the warmer part of the mass will rise and the cooler portions will sink.
conduction
In heat, energy transfer from particle to particle within certain materials, or from one material to another when the two are in direct contact.
density
A ratio that compares the mass of an object to its volume. Density= mass x volume
tension
A force that pulls on a material, as with divergent boundaries.
compression
A type of stress that squeezes the rock, causing it to break or fold, as with convergent boundaries.
shear
stress that pushes masses of rock in opposite directions, in a sideways movement, as in transform boundaries
island arcs
Volcanic island chains which follow the trenches' curves. Ex: Aleutian and Mariana Islands