Herron, T. Hess, H. Engel et al. Boulder, Colo. Holmes, A. Glasgow Trans. Karig, D. Research 75, — Sclater, J. Space Phys. Spiess, F. Vine, F. Caryl-Sue, National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format.
When you reach out to them, you will need the page title, URL, and the date you accessed the resource. If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service. Any interactives on this page can only be played while you are visiting our website.
You cannot download interactives. These tectonic plates rest upon the convecting mantle, which causes them to move. The movements of these plates can account for noticeable geologic events such as earthquakes, volcanic eruptions, and more subtle yet sublime events, like the building of mountains.
Teach your students about plate tectonics using these classroom resources. Ocean currents are the continuous, predictable, directional movement of seawater driven by gravity, wind Coriolis Effect , and water density. Ocean water moves in two directions: horizontally and vertically. Horizontal movements are referred to as currents, while vertical changes are called upwellings or downwellings. Explore how ocean currents are interconnected with other systems with these resources.
In , after decades of tediously collecting and mapping ocean sonar data, scientists began to see a fairly accurate picture of the seafloor emerge. The Tharp-Heezen map illustrated the geological features that characterize the seafloor and became a crucial factor in the acceptance of the theories of plate tectonics and continental drift. Today, these theories serve as the foundation upon which we understand the geologic processes that shape the Earth.
The theory of plate tectonics revolutionized the earth sciences by explaining how the movement of geologic plates causes mountain building, volcanoes, and earthquakes. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Seafloor spreading is a geologic process in which tectonic plate s—large slabs of Earth's lithosphere —split apart from each other.
Seafloor spreading and other tectonic activity processes are the result of mantle convection. Convection current s carry heat from the lower mantle and core to the lithosphere. Seafloor spreading occurs at divergent plate boundaries.
The less-dense material rises, often forming a mountain or elevated area of the seafloor. Eventually, the crust cracks. Hot magma fueled by mantle convection bubbles up to fill these fracture s and spills onto the crust. This bubbled-up magma is cooled by frigid seawater to form igneous rock. Seafloor spreading occurs along mid-ocean ridge s—large mountain range s rising from the ocean floor. The East Pacific Rise is a mid-ocean ridge that runs through the eastern Pacific Ocean and separates the Pacific plate from the North American plate, the Cocos plate, the Nazca plate, and the Antarctic plate.
Since the seafloor on each side of a midocean ridge moves in opposite directions, each side belongs to a different lithospheric plate. Midocean ridges, transform faults and fracture zones are the key surface features produced by seafloor spreading.
In detail, midocean ridges are made up of short offset segments. The curved linear features running perpendicular to midocean ridges are fracture zones and transform faults. Fracture zones and transform faults make up parts of each linear feature. The transform faults lie between two neighboring offset ridges. The motion of the plates on opposite sides of the transform fault are consistent with seafloor being produced at each ridge and moving away to each side.
Seafloor spreading determines plate motion around a midocean ridge. Midocean ridges are always plate boundaries.
0コメント