Question

mid - atlantic ridge
distance from ridge (km)
which sequence correctly lists the crust samples from youngest to oldest?
choose 1 answer:
a ( y \to x \to z )
b ( y \to z \to x )
c ( z \to x \to y )
d ( z \to y \to x )

Explanation:

At mid-ocean ridges like the Mid-Atlantic Ridge, new oceanic crust forms at the ridge and moves outward in both directions. This means crust closest to the ridge is youngest, and crust farthest from the ridge is oldest.

• Sample Y is closest to the ridge (0 km distance), so it is the youngest.
• Sample X is 40 km from the ridge, making it older than Y but younger than Z.
• Sample Z is 80 km from the ridge, so it is the oldest.

Answer:

A. $Y
ightarrow X
ightarrow Z$