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Earth’s Structure and Formation Expository Essay

Question 1: Advances in Determining the Age of the Earth and the Importance of Radioactivity

There are several technological advances that may be used to determine the age of the earth. First, radioactive decay can act as a valuable process in establishing the age of rocks. Following the discovery of radioactive decay, several other age dating techniques emerged, which enabled scientists to position absolute ages against the geological scale of time.

Radioactivity discovery and the knowledge that the quantities of neutrons in an element may diverge to form isotopes, facilitated in establishing two key tools that are useful in understanding geosphere (Fried, 2000). Radiometric age dating, which is the first tool, becomes founded on the fact that some isotopes have predictable decay rates, on top of being unstable.

Hence, knowledge of the isotope that was present during the formation of the rock and the rate at which the unstable isotope changes can be used to establish the age of the rock depending on the current isotopic composition of the rock. The second tool utilizes stable isotopes, whereby the relative quantity of isotopes in an organic compound or rock may aid in establishing its origin.

There exist other technologies that can be used to study geology, besides, isotopic geology. For instance, laboratory technologies, which include the use of new tools to find out the composition of organic compounds and rocks, can also be used to study geology (Fried, 2000).

There is also, advancement in the ability to determine magnetic features of materials as well as understanding magnetism. In addition, paleomagnetism enables geologists to establish the age of rocks and the latitude of the rock during the cooling process. Paleomagnetism has enabled geologists to trace past positions of continents.

Lastly, advances in laboratory tools of analysis become steered by development in field techniques. The majority of such techniques are remote sensing in nature. Some remote sensing tools include seismology and sonar.

Question 2: What makes the Earth a Habitable Place?

The earth is habitable as it gets positioned at a distance from the sun which allows water to exist in all its forms, including the liquid form. Besides, the earth has an atmosphere and a magnetic field that obstructs detrimental radiation from the sun. Also, the earth has vigorous tectonic processes, which stimulate an exchange between external and internal layers of the planet, in order to reuse biological and geological substances.

However, the earth was not habitable from the start. In the early stages of formation, the earth was not habitable, due to the bombardment by planetesimals, during the Big bang theory. A few seconds after the Big bang neutrons and protons began to form nuclei of elements such as Helium and Hydrogen. In the first hundred thousand years after the bang, no matter of the state, that is common, existed.

Rather, the earth became dominated by radiation. Following radiation, nuclei joined with free electrons, to form atoms and matter grew dominant over energy, gradually. 200 Million years later, galaxies began to form out of condensed gas, and the solar system emerged.

Question 3: Alfred Wegener, Skepticism and Proof of the Continental Drift Hypotheses

Wegener suggested the theory of the continental drift. However, Wegener’s work became viewed with skepticism. Some scientists argued that Wegener’s idea of continents drifting on the earth’s surface was illogical. This was because Wegener did not explain where the energy to drive the movement would originate. Also, a physicist demonstrated that continental drifting over the surface of the earth, would make all continents drift to the equator (Monroe, 2012).

This was a key source of disprove for Wegener’s theory, since not all continents are around the equator, billion of years later. However, the acquisition of new data supported Wegener’s hypothesis. The discovery of regular reversals from magnetization of bordering strips of the ocean floor supported the idea of seafloor spreading (Monroe, 2012).

Wegener supported his theory by use of disciplines including biology, geography and geology. He inquired how coal deposits became sited near the North Pole and how African plains demonstrated glaciations. Besides, Wegener demonstrated areas that fossils of identical prehistoric species became dispersed.

Question 4: Seismic Tomography

Seismic tomography employs seismic waves in order to visualize all the three sides of the mantle (Iyer, 1993). Scientists then form images of individual slices in the interior of the earth, which can be used to explain geology and the composition of the earth’s interior.

Seismic tomography shows magnetic variances from the floor of the ocean, which confirms the occurrence of the sea floor spreading. Also, scientists can see aspects like the Indian ridge systems and the East-pacific rise, as well as volcanoes near the Pacific Rim, which confirm the presence of plate tectonics (Iyer, 1993).

Question 5: The Laws of Thermodynamics

The laws of thermodynamics determine the motions that result in the formation of mountains and oceans. The first law of thermodynamics states that energy can not be destroyed, although, it may be converted from one state to another. The second law proposes that energy tends to disband from areas of high concentration to areas of low concentration. In order to explain the motions that result in the formation of mountains and oceans, we shall focus on the second law.

During the formation of the solar system, a thin stream of Helium and Hydrogen dispersed to space. Thus, heavier elements became formed from lighter ones, including stars and planetary systems. In the process, the planet developed surface features such as oceans and mountains.


Fried, B. (2000). Rocks and minerals. Portland, Me: Weston Walch.

Iyer, H.M. (1993). Seismic tomography: Theory and practice. New York: Chapman & Hall.

Monroe, J. (2012). The changing earth: Exploring geology and evolution. Belmont, CA: Brooks/Cole.

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