Question

Which of the following is a key, feature of angular unconformity?

A. Rock layers have been destroyed by a seismic event.
B. Rock layers have been heated by a volcanic hot spot.
C. Rock layers have been stretched and thinned.
D. Rock layers have been tilted or folded.

Answer 1

An angular unconformity is characterized by horizontal sedimentary rock layers resting on top of tilted or folded sedimentary rock layers and is evidence of historical orogenic events and subsequent erosion and deposition.

Step-by-step explanation:

The key feature of an angular unconformity is that horizontal layers of sedimentary rock lie on top of tilted or folded layers of sedimentary rock. This geological structure indicates that the underlying layers were lifted, often due to an orogenic event, and subsequently eroded. Renewed deposition of sedimentary layers then takes place on the eroded surface, forming the angular unconformity. An example of this can be seen at Siccar Point in Scotland, where older rocks that became exposed above sea level got tilted or folded, eroded, and then had new horizontal layers of sedimentary rock deposited on top of them, creating a distinct angle between the older and younger layers.