What problem does an unconformity present?

Question

A. It weakens the crust so earthquakes are more prevalent.
B. It allows magma to escape to the surface of Earth.
C. It leaves a gap in the geological record.
D. It doesn't contain any fossils for geologists to study.

Answer 1

The closest is C. An unconformity occurs usually when geological layers have been subject to stresses which causes folds. These are then worn down over millions of years before new strata are deposited on top of the old strata with a gap in the geological record (as you said). Unconformities were first observed and understood by James Hutton when he saw the unconformity at St. Abbs Head in Scotland.