Which information is needed to construct a geomagnetic time scale? Select the two correct answers.
the length of the mid-oceanic ridge
the average speed of tectonic plates on Earth
the age of rocks along the surface of Earth***
the magnetic direction of rocks along the surface of Earth***
The two correct answers to construct a geomagnetic time scale are:
1. The age of rocks along the surface of Earth
2. The magnetic direction of rocks along the surface of Earth
To construct a geomagnetic time scale, you need two pieces of information:
1. The age of rocks along the surface of the Earth: This is important because different rocks form at different times in Earth's history. By determining the age of rocks using various dating techniques (e.g., radiometric dating), scientists can establish a chronological sequence of events and their corresponding magnetic signatures.
2. The magnetic direction of rocks along the surface of the Earth: Earth's magnetic field has changed throughout its history, and rocks record the direction of the magnetic field at the time of their formation. By studying the magnetic orientation of rocks (e.g., through paleomagnetism), scientists can determine the past changes in Earth's magnetic field and establish a geomagnetic time scale.
Therefore, the correct answers are:
- The age of rocks along the surface of Earth
- The magnetic direction of rocks along the surface of Earth