A fault (F) breaks three layers of sedimentary rock (S). An igneous intrusion (I1) has broken through the bottommost layer of rock. A second igneous intrusion (I2) has moved up the fault and pooled on top of the uppermost layer of rock. Which event would be considered the youngest?a. The intrusion of I2 is the youngest event. We can know this because I2 sits on top of all other rocks.
b. The intrusion of I1 or I2 is the youngest event. Without more information, we cannot know which igneous rock is youngest.
c. Faulting of rock along F is the youngest event. We know this because all three layers of sedimentary rock have been broken.
d. Deposition of the three sedimentary layers, S, is the youngest event. We know this because the fault underlies the igneous rocks.