Plate Tectonics and Seafloor Spreading

Questions and Answers

Convection currents in the Earth's crust

Convection currents in the Earth's mantle (correct)

Tidal forces

Wind and ocean currents

Seafloor compression

Seafloor tension

Seafloor spreading (correct)

Seafloor erosion

Magnetic reversal (correct)

Magnetic fluctuations

Magnetic polarity

Magnetic anomalies

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Subduction Signup and view all the answers

Study Notes

The theory that the Earth's lithosphere is divided into large plates that move relative to each other
Plates can be in motion due to convection currents in the Earth's mantle
There are 7 major plates and several smaller ones

The process of new oceanic crust being created at mid-ocean ridges
Magma rises from the Earth's mantle to the surface, solidifying into new crust
As new crust is created, older crust is pushed away from the ridge, resulting in the seafloor moving away from the ridge

Magnetic Reversals: rocks on either side of a mid-ocean ridge show alternating magnetic polarities, indicating that the Earth's magnetic field has reversed over time
Age of Rocks: rocks closest to the ridge are younger, while those further away are older, indicating that the seafloor is moving away from the ridge
Mid-Ocean Ridge Topography: the ridge is characterized by a central rift valley, with symmetrical topography on either side

Divergent: where two plates are moving away from each other, resulting in seafloor spreading (e.g. mid-ocean ridges)
Convergent: where two plates are moving towards each other, resulting in subduction or collision
Transform: where two plates are sliding past each other horizontally, without creating or destroying crust

Earthquakes and Volcanoes: plate movement is responsible for the distribution of earthquakes and volcanoes
Creation of Oceanic Crust: seafloor spreading is the primary mechanism for creating new oceanic crust
Shaping of the Earth's Surface: plate tectonics has played a crucial role in shaping the Earth's surface over billions of years

The Earth's lithosphere is broken into large plates, ranging from 7 major plates to several smaller ones, that move relative to each other.
Convection currents in the Earth's mantle are the driving force behind plate motion.

Mid-ocean ridges are the birthplace of new oceanic crust, created through the upwelling of magma from the Earth's mantle.
As new crust forms, older crust is pushed away from the ridge, resulting in the seafloor moving away from the ridge.
This process is continuous, with the seafloor constantly moving away from the mid-ocean ridges.

Magnetic Reversals: rocks on either side of a mid-ocean ridge exhibit alternating magnetic polarities, indicating the Earth's magnetic field has reversed over time.
Age of Rocks: the age of rocks increases with distance from the ridge, with the youngest rocks closest to the ridge.
Mid-Ocean Ridge Topography: the central rift valley and symmetrical topography on either side of the ridge are characteristic features.

Divergent Boundaries: plates moving away from each other, resulting in seafloor spreading, e.g., mid-ocean ridges.
Convergent Boundaries: plates moving towards each other, resulting in subduction or collision.
Transform Boundaries: plates sliding past each other horizontally, without creating or destroying crust.

Earthquakes and Volcanoes: plate movement is responsible for the distribution of earthquakes and volcanoes on the Earth's surface.
Creation of Oceanic Crust: seafloor spreading is the primary mechanism for creating new oceanic crust.
Shaping of the Earth's Surface: plate tectonics has played a crucial role in shaping the Earth's surface over billions of years, resulting in the formation of mountains, volcanoes, and ocean basins.