Spaceship Earth: Our oasis in the emptiness of space: The dynamic planet.

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”

Distribution of warm-water fossils

Rocks of same age cross continents

Topography of EarthHuge 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, 1991An 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.