Earth’s Geology – 3 primary layers
Core, Mantle, and Crust
 Inner core is solid metal
(iron and nickle)
 Outer Core is molten metal
 Rocky mantle (solid silicate)
 Molten upper mantle
(athenosphere)
 Crust – thin silicate rock (lithosphere)

Earth’s Crust has ~15 major plates http://www.windows2universe.org/earth/interior/plate_te ctonics.html

Convection currents cause plate tectonics.
 Plates move 2-15 cm per year – about the rate your fingernails grow!

 Scripps Researchers Discover New Force Driving
Earth's Tectonic Plates
'Hot spots' of plume from deep Earth could propel plate motions around globe
 Scripps Institution of Oceanography / University of
California, San Diego
 http://scrippsnews.ucsd.edu/Releases/?releaseID=1178


At least twice the landmasses have joined to form a
“supercontinent”.
Pangea existed about
220 mya

 Choose the AVI and step it along.
http://www.ucmp.berkeley.edu/geology/tectonics.html

Three types of plate boundaries: divergent, transform, and convergent.

Two plates move apart as magma
(liquid rock) rises upward to create new lithosphere.

Divergent plates -

Spreading oceanic plates result in formation of new crust on the ocean’s bottom (“seafloor spreading”) and subduction of heavier oceanic plates beneath less dense continental plates.

Mid atlantic ridge – a giant undersea mountain range, started forming 20 million years ago as
Africa and S. America separated.

Generate earthquakes – eg.
San Andreas Fault

 If two cities lie on different tectonic plates, and those plates are moving so that the cities are approaching each other, how many years will it take for the two cities to be situated adjacent to each other?
 Los Angeles is 630 km (380 miles) southeast of San
Francisco. The plate under Los Angeles is moving northward at about 36 mm per year relative to the plate under San Francisco. Given this average rate of plate movement, how long will it take for Los Angeles to be located next to San Francisco?

If oceanic and continental plates converge – one plate is subducted and leads to volcanism. – eg. Japan,
Mariana Trench, Cascades
Mtns, Andes Mtns.

Continental-continental convergence –
Himilayas and Appalacian Mountains




Volcanoes when molten rock, hot gas, or
 ash erupt through Earth’s surface.

Form at divergent plate boundaries and subduction zones, and over hot spots.
Video – Ring of Fire IMAX
Earthquakes shaking and release of energy along tectonic plate boundaries.

Animation showing cumulative earthquakes
Video http://www.pbs.org/wgbh/no va/earth/earthquakedetection.html

 Some “chains of volcanoes” form when mantle passes over a relatively small, long-lasting, and exceptionally hot regions -- called hotspots – that provide localized sources of high heat energy (thermal plumes)

Hawaiian (and Galapagos) islands form from “hotspot”

Figure 8.7
Plate movement over a hot spot. The Hawaiian Islands were formed by volcanic eruptions as the Pacific Plate traveled over a geologic hot spot. The chain of inactive volcanoes to the northwest of Hawaii shows that those locations used to be over the hot spot. Numbers indicate how long ago each area was located over the hot spot (in millions of years).

Yellowstone Volcano progression is evidence for hotspot under mantle.

 Plot the data for recent volcanic eruptions on the map on the worksheet – Tectonic Plates Part 1.

Ring of Fire – lots of volcanoes at plate boundaries

Tsunamis can follow earthquakes and volcanos.
 Dec 26, 2004 Tsunami, triggered by earthquake off
Sumatra, killed 228,000 people

Tsunami strikes Northern Japan on
March 11 th , 2011
 Tsunami followed an
Earthquake of magnitude 8.4




Earthquakes
Volcanoes when molten rock, hot gas, or
 ash erupt through Earth’s surface.
 shaking and release of energy along tectonic plate boundaries.
Animation showing cumulative earthquakes
Form at divergent plate boundaries and subduction zones, and over hot spots.
Video – Ring of Fire IMAX
 Video http://www.pbs.org/wgbh/no va/earth/earthquakedetection.html

Landslides may occur on hilly ground
Liquefaction of recent sediments causes buildings of sink
Two adjoining plates move laterally along the fault line
Earth movements
Cause flooding in
Low-lying areas
Shock waves
Epicenter
Focus
Earthquakes