Question

certain magnetic minerals in rocks can record the direction and intensity of earths magnetic field at the time they are formed. the direction of the magnetic field has reversed several times during earths history. these reversals are recorded in the bedrock of the ocean floor.
the model below shows some information about the age and magnetic polarity of ocean floor bedrock along the juan de fuca ridge system.
juan de fuca ridge model image: includes map of the ridge, age of oceanic crust scale (present to 10 million years), key for magnetic field polarity (normal, reversed), and fault lines

1. which statement correctly compares locations on the juan de fuca ridge model?

(1) the basalt at location a is older than the basalt at location b.
(2) a greater amount of outward flow of energy from earths interior occurs at location a than at location b.
(3) the magnetic polarity of basalt at location a is the same as the magnetic polarity of basalt at location b.
(4) the motion of the tectonic plate is from location b to location a.

Explanation:

1. Analyze option (1): Oceanic crust forms at mid-ocean ridges (like the Juan de Fuca Ridge crest) and moves outward, so crust farther from the ridge is older. Location A is closer to the ridge than B, so A is younger. This is incorrect.
2. Analyze option (2): Outward energy flow from Earth's interior is highest at the ridge crest (where new crust forms). Location A is closer to the ridge crest than B, so more energy flow occurs at A. This is correct.
3. Analyze option (3): The key shows location A has reversed polarity, while location B has normal polarity. They are not the same. This is incorrect.
4. Analyze option (4): Tectonic plates move away from the mid-ocean ridge crest. Location B is farther from the ridge than A, so motion is from A to B, not B to A. This is incorrect.

Answer:

(2) A greater amount of outward flow of energy from Earth's interior occurs at location A than at location B.