1.Explain why Apparent Polar Wandering curves demonstrated that the plates moved
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Question
1.Explain why Apparent Polar Wandering curves demonstrated that the plates moved over time. What relationship of the Earth’s magnetic field to the Earth’s surface enables geologists to determine the latitudinal position of various plates in the geologic past? Give 4 other evidences of plate tectonics. 1.Explain why Apparent Polar Wandering curves demonstrated that the plates moved over time. What relationship of the Earth’s magnetic field to the Earth’s surface enables geologists to determine the latitudinal position of various plates in the geologic past? Give 4 other evidences of plate tectonics.Explanation / Answer
The formation of a rock containing magnetized minerals results in the recording of the magnetic field at the time of rock formation. Magnetic reversals are identified when
1. the magnetic north in the rock record coincides with the present-day geographic south.
2. the magnetic south in the rock record coincides with the present-day geographic north.
The azimuthal alignment of magnetic fields in rock record is measured using a magnetometer and compared with the position of geographical north and south of today. The relation of the magnetic field to the surface help geologists identify the spatial orientations and temporal zones in which the past continents existed because:
1. the rock record which shows reversed polarity in magnetized minerals indicates that the landmass containing the rock record rotated over time.
2. the magnetic inclinations measured from two rock records on different present-day continents usually show different directions which indicate that they were aligned differently in the past.
3. the ages of rocks containing mineralized minerals are indicative of the speed at which the continents moved relative to each other.
Thus, gathering the azimuthal data and ages from rocks containing magnetized minerals, the geographical position of the past continental as well as oceanic plates are determined.
The four other pieces of evidence of plate tectonics are:
1. Fossils: same species of plants, e.g Glossopteris, and animals, e.g. Lystrosaurus, have been found in Antarctica, India, Africa and Australia. This shows that the landmasses were once joined in the past.
2. Glacial deposits: the striations in glaciers found in India, South America, Africa and Australia point in a diverging direction which indicates the landmasses moved apart from each other over geological timescales.
3. Coal deposits: North America and Europe have strikingly similar formations of coal implying that the climate was similar in both the regions and that they were a part of one landmass.
4. Activities on plate boundaries: volcanic eruptions and earthquakes are ubiquitous along the boundaries of plates which supports the fact that there are forces between two plates leading to such intense events.
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