Earth and Space - Structure of the Earth

Flashcards covering Earth's structure, crust, mantle, core, plate tectonics history, and plate boundaries.

What are the main structural layers of the Earth?

Crust, mantle, and core (which includes the outer core and inner core).

What is the crust and what are its types?

The outermost solid layer of the Earth; oceanic crust is denser, thinner, and mainly basalt; continental crust is less dense, thicker, and mainly granite.

What is the mantle and its relation to the lithosphere?

The mantle lies beneath the crust, up to about 2900 km thick, and is composed of hot, dense, iron and magnesium-rich solid rock. The lithosphere consists of the crust and the upper mantle and is broken into tectonic plates.

What are the two parts of the Earth's core and their properties?

The outer core is liquid nickel/iron with molten rock; the inner core is solid iron/nickel and hotter than the Sun's surface.

What did Alfred Wegener propose, and what happened to his theory?

Continental drift: continents were once joined in a supercontinent (Pangaea) and drifted apart; lacked a mechanism, which the modern theory of plate tectonics later provided through mantle convection.

What are the three types of plate boundaries and how do plates move at each?

Divergent boundaries—plates move apart; Convergent boundaries—plates move toward each other and collide; Transform boundaries—plates slide past one another.

What occurs at divergent plate boundaries and give examples?

New crust forms from magma as plates move apart; features include mid-ocean ridges and rift valleys; examples: Mid-Atlantic Ridge and Great Rift Valley.

What occurs at convergent plate boundaries and what features form?

Two plates collide; subduction typically occurs (oceanic beneath continental) forming ocean trenches and volcanic arcs; continental-continental collisions form large mountains (e.g., the Himalayas).

What occurs at transform plate boundaries?

Two plates slide horizontally past each other, causing earthquakes; stress is redistributed; example: San Andreas Fault.

What is the lithosphere?

The outer rigid shell comprising the crust and the upper part of the mantle, broken into tectonic plates.

How do oceanic and continental crust differ?

Oceanic crust is basaltic, denser and thinner; continental crust is granitic, less dense and thicker.