Ch.2 & 3 Marine Provinces & Plate Tectonics

Pacific Ocean

50% of all ocean volume, 33% of Earth's surface area, and the deepest ocean with the Marianas Trench.

Atlantic Ocean

23% of all ocean volume, 17% of Earth's surface area, characterized as very narrow and salty.

Indian Ocean

20% of all ocean volume, 14% of Earth's surface area, known for having the highest salinity range.

Southern Ocean

5.4% of all ocean volume, 4.3% of Earth's surface area, recognized as the coldest and youngest ocean, formed approximately 34 million years ago.

Arctic Ocean

1.4% of all ocean volume, 3.1% of Earth's surface area, identified as the shallowest ocean.

Sea

A subsection of the ocean, commonly having reduced circulation, smaller and usually touching land.

Billabong

An oxbow lake in Australia; a pond or still body of water created when a river changes course and some water becomes trapped.

Lithosphere

Includes both oceanic and continental crust, as well as the brittle upper portion of the mantle, behaving as a solid, rigid layer.

Asthenosphere

Includes a portion of the upper mantle, behaving as a solid, ductile (flexible) layer.

Continental Crust

Average composition is granodiorite/diorite (felsic, more SiO2) with an average density of approximately 2.7 g/cm^3.

Oceanic Crust

Average composition is basalt (mafic, less SiO2, more Fe, Mg) with an average density of approximately 2.9 g/cm^3.

Isostasy

The equilibrium that exists between the Earth's crust upon the underlying mantle, requiring a balance between internal pressures under land blocks and ocean basins.

Earth's Plates

Currently there are seven major plates and approximately eight minor plates that compose Earth's crust.

Convection cells

Cells in the mantle that cause plate movement, created by unstable radioisotopic elements breaking down and releasing heat, and residual heat from Earth's formation.

Divergent Plate Boundary

Formed when plates are moving away from one another.

Convergent Plate Boundary

Plates move towards one another.

Oceanic-Oceanic

A type of convergent plate boundary.

Oceanic-Continental

A type of convergent plate boundary.

Continental-Continental

A type of convergent plate boundary.

Transform Plate Boundary

Characterized by plates that move past or parallel to one another.

Scientific Theory

A well-tested explanation of something in nature.

Hypothesis

A tentative explanation that can be tested by further investigation.

Scientific Law

A statement that summarizes the relationship between variables.

Alfred Wegener

German Meteorologist / Arctic Explorer who proposed the theory of continental drift in 1912.

Pangaea

A proposed single supercontinent by Alfred Wegener.

Panthalassa

A proposed single super ocean by Alfred Wegener.

Wegener's Evidence

1. Geographic Fit 2. Fossil Distribution 3. Mountain Range ages 4. Rock Sequences Glacial Striations.

Plate Tectonic Theory

The Earth is divided into discrete plates that move relative to one another.

Hotspots

Volcanic region in the interior of a plate fed by an underlying mantle plume.

Mantle Plumes

Columns of hot rock that rise up from deep within the Earth and push through the plate above.

Paleomagnetism

The study of the Earth's magnetic field preserved in rocks.

Plate Movement

We can determine rates of plate movement by dating rocks around spreading centers.