Question

Rock layers labeled A to J from bottom to top. Layers A, B, and C are not horizontal, and are pushed up toward layer E. Layers E, F, I, and J are horizontal. A fault is labeled G, and runs from layer A to the bottom of layer I. Rock layers to the right of the fault are shifted up and do not include layer F. Layer H is Y-shaped, starting below layer A up to layer E, on the right side of the fault. Arrows point to unconformities at the bottom of layer E on both sides of the fault, and the top of layer E on the right side of the fault.
Use the drop-down menus to answer the questions about the diagram.

Letter H is a(n)
.

Which of these is youngest?

Which of these was eroded?

Which happened first?

Answer 1

- H is an igneous intrusion (a dike/pluton that cuts upward through the older rocks).

- Youngest: layer J (the topmost unit).

- Eroded: the tops of A–C were eroded before E was deposited (and additionally the top of E was eroded on the right side).

- Happened first: deposition of the oldest rock (layer A) — i.e., formation of A (then B and C).