Plate Tectonics The Earth’s crust consists of a number of plates which are in motion (quite slow)
The Layers of the Earth
The movement of crustal plates results from convection currents in the Mantle. Heat from the formation of the Earth and radioactive decay escapes at the Earth’s surface.
Some plates contain mainly oceanic crust and some contain both continental and oceanic crust.
Shortcut to Bullard Fit of Continents
The Glomar Challenger was the first research vessel specifically designed in the late 1960s for the purpose of drilling into and taking core samples from the deep ocean floor.
Remote Sensing- uses energy signals from Earth to determine many different kinds of information
Earthquake Zones
Earthquake and Volcano Activity closely matches the plate boundaries!
Mid-Ocean Ridges
Computer-generated detailed topographic map of a segment of the Mid-Oceanic Ridge
Shortcut to Sea Floor Spreading Shortcut to Formation of Ocean Crust
There is evidence of “Sea floor spreading” on either side of the Mid-Atlantic Ridge
Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle.
Iceland is right on an oceanic-oceanic Divergent Plate Boundary
Plate Boundaries
Convergent boundaries are where plates are moving toward each other, and sometimes one plate sinks (is subducted) under another. The location where sinking of a plate occurs is called a subduction zone. subduction
Heat from friction melts rock and the magma forms volcanoes
Mount Baker (Washington)
Mount Rainier (Tacoma in foreground)
Deep trenches are formed in the ocean floor where subduction begins
Oceanic-oceanic convergent boundaries produce volcanic Island Arc’s
An oceanic-oceanic convergent boundary. They also produce a trench
Where might we find trenches?
The Mariana Trench is the deepest known trench. The bottom of the trench (Challenger Deep) is further below sea level than Mount Everest is above it. The trench has a maximum depth of 10,911 m (35,798 feet) below sea level.
Continental-continental Convergent plate boundaries can produce mountain ranges.
Transform Boundaries The zone between two plates sliding horizontally past one another is called a transform-fault boundary, or simply a transform boundary. transform faulting
Some Transform Boundaries
The San Andreas Fault
Measuring displacement in a small transform fault
Remote sensing from satellites can detect small movements on either side of a fault.
In Transform Boundaries, no new crust is formed and no crust is destroyed. Earthquakes often occur along transform boundaries.
Hot Spot Volcanoes
Hot Spot Volcanoes are not at plate boundaries
Oceanic Crust moves over fixed hot spot.
hot spot volcanoes
The oldest volcanic island is farthest from the hot spot in the direction of the plate movement.
Eroded volcanic islands which are below the surface are called Seamounts
The trail of underwater mountains created as the the tectonic plate moved across the Hawaii hotspot over millions of years, known as the Hawaiian-Emperor seamount chain, or the Emperor Seamounts (Which direction do you think the Pacific Plate is moving?)
Mauna Loa, comprising over half of the Big Island, is the largest shield volcano on the planet. The measurement from the base locally depressing the sea floor in the Hawaiian Trough to its peak is about 17 km (56,000 feet) Sea Level to peak of Everest is 8,848 meters (29,028 feet)