20090523

Astronomy quiz question: young Moon features

Astronomy 210 Quiz 7, Spring Semester 2009
Cuesta College, San Luis Obispo, CA

Which feature on the moon is the youngest?
(A) Craters on top of flat lava plains.
(B) Flat lava plains.
(C) Craters partially filled in with flat lava plains.
(D) (There is a tie.)

Section 30676
(A) : 28 students
(B) : 13 students
(C) : 10 students
(D) : 4 students

Correct answer: (A)

According to the "law of superposition," layers on top are younger than layers beneath (if there is no crustal upheaval). Thus the flat lava plains are newer than the craters partially filled in by them, and the flat lava plains are older than the craters on top of them.

"Difficulty level": 55% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.43

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