Earth Surface Research Paper

Darlene Garcia
GEO 151
Prof. Denyse Lemaire
WA1
Feb. 2010

1. What are the relationships among Earth's mantle, crust, asthenosphere, and lithosphere?

The core is divided into three major compositional layers. The crust on Earth’s surface, the rocky mantle beneath the crust and the metallic core which is the center of the Earth. While distinct and separate parts of Earth, they are all interconnected.
The metallic inner core is solid, surrounded by a liquid (molten) outer core. Most of the mantle is solid, except for a layer very close to the crust boundary: the asthenosphere. The asthenosphere is plastic-like and partially molten. On top of the asthenosphere there is a rigid layer of solid rocks called the lithosphere, formed by the uppermost mantle and
the crust.

In addition to the Earth’s mantle, crust, asthenosphere and lithosphere there are also hot spots that seem to be rooted in the mantle and do not move with the plates. The movement of lithospheric plates over hot spots have created long chains of old extinct volcanos which end in an active one, in the location of the plate currently over the hot spot. These hot spots show the interconnectivity of the different regions of our Earth.

2.By what processes did the planets form from the clouds of gas and dust? What are some of the main differences between the Earth-like planets and the giant outer planets such as Jupiter and Saturn?

Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star. This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. Like an ice skater that spins faster as she pulls in her arms, the cloud began to spin as it collapsed. As the cloud grew hotter and denser in the center, with a disk of gas and dust surrounding it that was hot in the center but cool at the edges. As the disk got thinner and thinner, particles began to stick together and form clumps. Some clumps got bigger, as particles and small clumps stuck to them, eventually forming planets or moons . Near the center of the cloud, where planets like Earth formed, only rocky material could stand the great heat.
The outer planets are subdivided into the gas giant or Jovian planets (Jupiter and Saturn), the ice giant planets (Uranus and Neptune), and Pluto. By far the largest planet is Jupiter, with a mass 318 times that of the Earth, while the other giant planets are more massive. Jupiter and Saturn are composed primarily of hydrogen and helium gas, like the Sun, but with rock and ices, such as frozen water, methane, and ammonia, concentrated in their cores.(www.science.nasa.gov)

3.Describe the Earth's magnetic field and the magnetic poles

Earth has two geographic poles: the North Pole and the South Pole.
They are the places on Earth's surface that Earth's imaginary spin axis passes through. Our planet also has two magnetic poles: the North Magnetic Pole and the South Magnetic Pole. The magnetic poles are near, but not quite in the same places as, the geographic poles. The needle in a compass points towards a magnetic pole. However, if you are near either pole, a compass becomes useless. It points towards the magnetic pole, not the true geographic pole. Those two poles could be quite far apart, and in different directions.
Earth's magnetic field is tilted a little bit. That angle is about 11 degrees. That's why the magnetic poles and the geographic poles are not in the same place. Earth's magnetic poles are far from its geographic poles. In 2005, the North Magnetic Pole (NMP) was about 810 km (503 miles) from the Geographic North Pole. The NMP was in the Arctic Ocean north of Canada. The South Magnetic Pole (SMP) was about 2,826 km (1,756 miles) from the Geographic South Pole. The SMP was off the coast of Antarctica in the direction of
Australia.(www.science.nasa.gov)

4.Differentiate between seamounts, guyots, and aseismic ridges.

Mountains on the sea floor that are conical in shape, and that exceed a height of one kilometer, are classified as seamounts. Islands are created when seamounts rise above the sea level - in the western Pacific Ocean there is a considerable concentration of such islands (estimated to be 10 000

in total). It is believed that seamounts are extinct volcanoes because of their high basaltic composition.
Guyots are simply seamounts that have been eroded to form a flat-topped platform. Again, it is uncertain as to how these seamounts eroded, but the most reasonable theory is that a guyot was eroded by wave action and then subsided, since the tops of these features are typically a few hundred meters below the current sea level. Evidence supporting this theory comes from the presence of dead reef corals found on the top of each guyot (corals characteristically only survive in very shallow water). (www.utdallas.edu)
Seamounts and guyots are often found in long sequences (or chains) that are collectively referred to as aseismic ridges (to distinguish them from the seismically-active ridges such as mid-oceanic ridges).

5.How does the age of sea-floor rocks compare with the age of continental rocks?

Seafloor rocks, as far as we currently know, are all considerably YOUNGER than the oldest continental rocks. In fact, it's created at the mid-ocean ridges and destroyed at the trenches through this process called subduction. It is interesting to note that the sea floor is composed of different material than the continents.(www.uofhawaii.edu)
When we compare this with the ages of the rocks on the continents, we find that the continental rocks are about 3.6 billion years old. In other words, they go back about three-quarters of the Earth's history. If the ocean floor rocks are much younger than the continental rocks, that must mean that the ocean floor is continuously being created and destroyed.

Works cited www.science.nasa.gov www.uofhawaii.edu
www.utdallas.edu