(A) The study of ancient, magnetized rocks Explanation: Palaeomagnetism is the study of ancient, magnetized rocks. It helps scientists understand the Earth's past magnetic field and the movement of continents over geological time scales by analysing the magnetic properties of rocks.

(C) Their magnetic alignment Explanation: Rocks suitable for paleomagnetic studies possess magnetic minerals that align themselves with Earth's magnetic field at the time of their formation. This alignment can be preserved over geological time periods, providing valuable information about past magnetic conditions.

(D) Alignment with Earth's magnetic field Explanation: Rocks become magnetized when magnetic minerals within them align with Earth's magnetic field at the time of their formation. This alignment creates a permanent magnetization in the rocks.

(C) Geomagnetic reversal Explanation: Geomagnetic reversal is the phenomenon where the Earth's magnetic field undergoes a complete reversal in polarity, causing the magnetic north and south poles to switch positions.

(B) Igneous rocks Explanation: Igneous rocks, such as basalts and volcanic lavas, are commonly used in paleomagnetic studies because they often contain magnetic minerals that align with Earth's magnetic field during solidification and preserve this alignment over time.

(B) Magnetic declination Explanation: Magnetic declination is the angular difference between the direction of true north (geographic north) and magnetic north at a specific location on the Earth's surface.

(B) Magnetometer Explanation: A magnetometer is the instrument used to measure the magnetic properties of rocks in paleomagnetic studies. It can detect the strength and direction of magnetic fields.

(A) Crust Explanation: Paleomagnetism provides important information about past magnetic field changes primarily in the Earth's crust, where rocks record the history of Earth's magnetic field.

(A) By providing evidence of past continental drift Explanation: Paleomagnetism provides evidence of past continental drift by showing that magnetic minerals in rocks preserve the orientation of Earth's magnetic field at the time of their formation, allowing scientists to reconstruct the movement of continents over geological time scales.

(C) Paleomagnetism Explanation: Paleomagnetism specifically focuses on the study of changes in the Earth's magnetic field over time, utilizing magnetic properties preserved in rocks and sediments.

(C) Igneous rocks Explanation: Igneous rocks, formed from solidification of magma or lava, often preserve the best record of Earth's ancient magnetic field due to the alignment of magnetic minerals during their cooling process.

(C) Magnetite Explanation: Magnetite is the primary mineral responsible for recording Earth's magnetic field in rocks due to its strong magnetic properties and common occurrence in igneous rocks.

(B) The strength of Earth's magnetic field in the past Explanation: Paleointensity refers to the measurement of the strength of Earth's magnetic field in the past, providing insights into variations in geomagnetic intensity over geological time scales.

(B) Potassium-argon dating Explanation: Potassium-argon dating is a common method used to date rocks in paleomagnetic studies, particularly in igneous rocks, by measuring the decay of radioactive potassium isotopes.

MCQ on Palaeomagnetism | Unlocking Geological History of the Earth with Paleomagnetic dating

Q: Answer

(A) Remanence Explanation: Remanence refers to the residual magnetization acquired by rocks during their formation, preserving the orientation of Earth's magnetic field at the time of their formation.

16. What is the term for the angle between the direction of magnetization in a rock and the horizontal plane?

(A) Magnetic inclination
(B) Magnetic declination
(C) Magnetic reversal
(D) Magnetic anomaly

(A) Magnetic inclination
Explanation: Magnetic inclination refers to the angle between the direction of magnetization in a rock and the horizontal plane, providing information about the latitude at which the rock formed.

17. How do scientists determine the geological history of the earth using paleo magnetism?

(A) By measuring the rate of radioactive decay
(B) By analysing the alignment of magnetic minerals
(C) By counting annual growth rings in trees
(D) By studying the composition of fossilized remains

(B) By analysing the alignment of magnetic minerals
Explanation: Scientists determine the geological history of the earth using paleo magnetism by analysing the alignment of magnetic minerals within the rocks relative to the Earth’s magnetic field at the time of their formation.

18. In what type of rocks can paleo magnetism provide evidence of past continental positions?

(A) Sedimentary rocks
(B) Metamorphic rocks
(C) Igneous rocks
(D) Organic rocks

(C) Igneous rocks
Explanation: Paleo magnetism can provide evidence of past continental positions primarily in igneous rocks, which record the orientation of Earth’s magnetic field at the time of their formation and can be used to reconstruct past continental drift.

19. How do scientists use paleomagnetic data to study plate tectonics?

(A) By measuring the age of rocks using magnetic properties
(B) By determining the rate of seafloor spreading
(C) By reconstructing past positions of continents
(D) By studying the composition of volcanic gases

(C) By reconstructing past positions of continents
Explanation: Scientists use paleomagnetic data to study plate tectonics by reconstructing past positions of continents based on the orientation of Earth’s magnetic field recorded in rocks, providing evidence of past continental drift.

20. What term describes the alignment of magnetic minerals in rocks with the Earth’s magnetic field at the time of their formation?

(A) Magnetic declination
(B) Magnetic anomaly
(C) Remanence
(D) Magnetic inclination

(C) Remanence
Explanation: Remanence refers to the residual magnetization acquired by rocks during their formation, preserving the alignment of magnetic minerals with the Earth’s magnetic field at that time.

21. Which phenomenon occurs when the magnetic minerals in a rock align with the current magnetic field upon cooling below the Curie temperature?

(A) Magnetic reversal
(B) Magnetic inclination
(C) Thermoremanent magnetization
(D) Isothermal remanent magnetization

(C) Thermoremanent magnetization
Explanation: Thermoremanent magnetization occurs when the magnetic minerals in a rock align with the Earth’s magnetic field upon cooling below the Curie temperature, preserving the direction of the magnetic field at the time of cooling.

22. How do scientists use paleo magnetism to study the past behaviour of the Earth’s magnetic field?

(A) By measuring the intensity of magnetic minerals in rocks
(B) By analysing the alignment of magnetic minerals in rocks
(C) By studying the composition of volcanic gases
(D) By dating the formation of sedimentary rocks

(B) By analysing the alignment of magnetic minerals in rocks
Explanation: Scientists use paleo magnetism to study the past behaviour of the Earth’s magnetic field by analysing the alignment of magnetic minerals in rocks, which record the orientation of the magnetic field at the time of their formation. This provides insights into past changes in the Earth’s magnetic field and its geomagnetic history.

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MCQ on Palaeomagnetism | Unlocking Geological History of the Earth with Paleomagnetic dating

16. What is the term for the angle between the direction of magnetization in a rock and the horizontal plane?

17. How do scientists determine the geological history of the earth using paleo magnetism?

18. In what type of rocks can paleo magnetism provide evidence of past continental positions?

19. How do scientists use paleomagnetic data to study plate tectonics?

20. What term describes the alignment of magnetic minerals in rocks with the Earth’s magnetic field at the time of their formation?

21. Which phenomenon occurs when the magnetic minerals in a rock align with the current magnetic field upon cooling below the Curie temperature?

22. How do scientists use paleo magnetism to study the past behaviour of the Earth’s magnetic field?

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