The following questions refer to the description and figure below.
The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labelled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley.

-How many other bands of sea-floor crust in the figure have the same magnetic polarity as the crust that directly straddles the rift valley?

Question

The following questions refer to the description and figure below.
The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labelled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley.
 
-How many other bands of sea-floor crust in the figure have the same magnetic polarity as the crust that directly straddles the rift valley?

Quizplus · Accepted Answer

There are four bands of sea-floor crust with the same magnetic polarity as the crust that directly straddles the rift valley. These bands are labeled I, II, IV, and VI. The alternating patterns of magnetic polarity on either side of the rift valley indicate the process of sea-floor spreading, as new crust is formed at the rift and moves away in opposite directions. The age of the crust also increases with distance from the rift valley, with the youngest crust closest to the ridge and the oldest crust farther away. At location III, the crust is about 1 million years old, and potassium-40 dating is typically used to date such rocks.

The Following Questions Refer to the Description and Figure Below