Question

the diagram shows a cross section through an area of earths crust.
which rock is most likely the youngest?
a. basalt
b. gneiss
c. granite
d. sandstone

Explanation:

To determine the youngest rock, we use the principle of cross - cutting relationships in geology. A rock that cuts through other rocks is younger than the rocks it cuts. Basalt (in the diagram, the dark - colored dike) cuts through gneiss, granite, and is also formed after sandstone (as the sandstone is at the top but the basalt dike intrudes through). So basalt is the youngest as it intruded after the other rocks.

Answer:

A. basalt