Which statements describe geologic gaps? check all that apply.

a. geologic gaps happen when volcanoes erupt.

b. when no sediment is deposited for a long time, angularities can result.

c. an unconformity happens when rocks do not follow normal geologic rules.

d. a geologic gap happens when rock is eroded before sediment is deposited.

e. an unconformity occurs when a rock layer’s relative age can be determined.