Earth Science Review

Flashcards about Earth's structure and plate tectonics.

Big Bang Theory and Earth's Age

The Earth is approximately 4.5 billion years old, formed from dust and rock collisions after a cosmic explosion.

Earth's Internal Structure

Earth is composed of layers: inner core (solid iron/nickel), outer core (liquid iron/nickel), mantle (asthenosphere and lithosphere), and crust (oceanic and continental).

Lithosphere

The cool, outermost layer of Earth, including the crust and uppermost mantle, characterized by its brittle nature.

Oceanic Crust

Younger, thinner crust composed of basalt (dark, high-density igneous rock).

Continental Crust

Older, thicker crust composed of granite (low-density igneous rock).

Alfred Wegener

Developed the theory of continental drift in 1912, proposing the existence of the supercontinent Pangea surrounded by the ocean Panthalassa.

Mid-Ocean Ridge

A chain of underwater mountains encircling the globe, entirely volcanic, and the largest geological feature on Earth.

Earth's Magnetic Field

Resembles a bar magnet with opposite polarities, and its periodic directional changes are recorded in magnetic particles within rocks.

Rifts

Areas where oceanic crust slabs separate at the mid-ocean ridge, allowing mantle material to melt and rise, forming new crust.

Lithogenous Sediment

Marine sediment derived from weathered rock.

Biogenous Sediment

Marine sediment consisting of shells or skeletons of marine organisms, providing information about past marine life and Earth's climate.

Seafloor Spreading

The process where seafloor moves away from mid-ocean ridges, creating new seafloor at divergent plate boundaries.

Subduction

The process where one plate descends under another at a trench, destroying old lithosphere.

Convergent Plate Boundary (Oceanic-Continental)

The denser oceanic plate descends into the mantle, while the continental crust remains intact, leading to older rocks on continental crust.

Convergent Plate Boundary (Oceanic-Oceanic)

A trench is formed as one oceanic plate dips below another; volcanoes may rise from the seafloor, creating islands.

Convergent Plate Boundary (Continental-Continental)

Mountain ranges are formed due to the lower density of continental crust causing plates to weld together.

Transform Plate Boundary

Plates slide past each other, neither creating nor destroying lithosphere; friction can cause earthquakes.