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Spaceship Earth: Our oasis in the emptiness of space: The dynamic
planet
Alfred Wegener (1903) suggested
and presented evidence that the
continents were once a single
supercontinent, called Pangea,
which divided ~ 200 Million
years ago into Laurasia and
Gondwanaland and later into
the continents we see today
(“continental drift”)
Fossils of the land-bound lizard Lystrosaurus were found in Africa,
Antarctica and India, suggesting that these continents were one
landmass during the life-time of this critter
Geologic evidence for “continental drift”
Rocks of same age cross continents
Distribution of warm-water fossils
Topography of Earth
Huge mountain ranges (ridges, like the Mid-Atlantic Ridge) circle the globe on the
ocean floors
The crust of Earth consists of 11 major tectonic plates
Epicenters of major earthquakes tend to occur along ocean ridges
and plate boundaries
The directions of movement of the major plates of Earth
Schematic diagram of an ocean spreading center:
Symmetry in magnetic reversals indicates sea-floor spreading.
Elongated
convection cells in
the plastic
asthenosphere
drive the
overlying rigid
lithospheric
plates.
The Hawaiian island chain is a wonderful example of plate tectonics
in the middle of a plate. It is fed by a stationary mantle plume under
Loihi, and the Pacific Plate glides over it at a speed of ~ 5 cm/year,
carrying the islands with it in a northwesterly direction.
Ages of the Hawaiian islands: An example of plate tectonics
associated with a mantle plume
Where were Earth’s continents in the geologic past?
Volcanoes: Pages 53 - 62
• Volcanoes are found on the surface of Earth and Venus; Mars has
fewer volcanoes with some signs of relatively recent volcanic activity.
• The volcanoes on Jupiter's satellite Io have turned the satellite inside
out; it is heated inside by the tidal flexing action of nearby massive
Jupiter.
• Volcanoes of ice may have created some of the features now frozen
into the bright smooth surface of Neptune's largest moon, Triton;
dark geyser-like plumes have been observed in the process of
eruption on the satellite.
Active volcanoes on Earth occur mostly along plate boundaries
Fire fountaining at Pu’u O’o, Hawaii, which has been erupting since 1983
Summit caldera of Mauna Loa volcano, Hawaii:
A basaltic shield volcano
Pahoehoe lava flows at Pu’u O’o, Hawaii.
A’a lava flows, Pu’u O’o, Hawaii.
Lava from Pu’u O’o, Hawaii, enters the ocean.
For more images, see: http://hvo.wr.usgs.gov/kilauea/update/#images
Mt. Pinatubo, June 12th, 1991
An explosive Island Arc volcano in the Philippines
Composite Volcanoes in the Andes (Chile)
Maat Mons, Venus
Rift zones on Venus
Olympus Mons on Mars, the tallest mountain in the Solar System
Olympus Mons on Mars, compared to the Hawaiian island chain
640 km
Right: Eruption of
the volcano Pele on
Jupiter’s moon Io.
Below: Top view of
volcano Pele
The volcanic plume (above) is 1,300
km wide and 600 km high.
Water volcanism on Saturn’s moon Enceladus
Dark, active nitrogen geysers on Neptune’s moon Triton.
The constant direction of the black streaks hints at a very thin atmosphere.
The interior structure
of Earth and the polar
wandering of its
magnetic field.