Why is the seafloor so recent and the continental crust so old? Where do we find the oldest continental rocks and the oldest seafloor? What are the different types of rocks? What is a fossil and what are they used for? What are hydrothermal vents, and why do we find them along mid-ocean ridges? Seismology What is a seismic wave? What is the difference between body waves and surface waves, and between P-waves and S-waves?
Why can't S-waves travel through liquids? How far can seismic waves reach? Why do P-waves travel faster than S-waves? Why is the interior of the Earth hot? What is the magnetic field of the Earth? Earthquakes and Faults Why do tectonic plates move? Brief history of the plate tectonics theory Before colliding with Asia, where was India? What is an earthquake? What is the highest magnitude an earthquake can reach? What are the biggest historical earthquakes?
Why do earthquakes happen in clusters? Where are earthquakes expected in the world, especially in Asia? What is a supercontinent? David Drayer. Jun 9, Explanation: Mid Ocean ridges are the source of new crustal material. Related questions What happens at a divergent plate boundary? What is one example of a hotspot?
What happens at a continent-oceanic convergent boundary? Is lava produced at a continent-oceanic convergent boundary, if so how? What is a transform boundary? Who developed the theory of plate tectonics and what were the major pieces of evidence in Also called lithospheric plate. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
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Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. 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. Weathering is the process of the weakening and breakdown of rocks, metals, and manmade objects. There are two main types of weathering: chemical and physical.
An example of chemical weathering is acid rain. Caused mostly by the burning of fossil fuels, acid rain is a form of precipitation with high levels of sulfuric acid, which can cause erosion in the materials in which it comes in contact.
An example of physical weathering is wind blowing across the desert playas. This process causes rocks to form a specific pyramid-like shape and they are called ventifacts.
Select from these resources to teach about the process of weathering in your classroom. 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. The rock cycle is a web of processes that outlines how each of the three major rock types—igneous, metamorphic, and sedimentary—form and break down based on the different applications of heat and pressure over time.
For example, sedimentary rock shale becomes slate when heat and pressure are added. The more heat and pressure you add, the further the rock metamorphoses until it becomes gneiss. If it is heated further, the rock will melt completely and reform as an igneous rock. Empower your students to learn about the rock cycle with this collection of resources. According to the United States Geologic Survey, there are approximately 1, potentially active volcanoes worldwide. Most are located around the Pacific Ocean in what is commonly called the Ring of Fire.
A volcano is defined as an opening in the Earth's crust through which lava, ash, and gases erupt. The term also includes the cone-shaped landform built by repeated eruptions over time. Teach your students about volcanoes with this collection of engaging material. Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth's lithosphere—split apart from each other.
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.
Earth is the planet we live on, the third of eight planets in our solar system and the only known place in the universe to support life. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content.
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