Why are the successive periods and epochs of the geologic time scale of unequal lengths?
A)The passage of time has been speeding up and the length of the day is variable.
B)It is based on evolution and some creatures are slow learners.
C)The periods and epochs are based on the duration of unique environments like basins, or events in earth history like extinctions, and orogenies which happen intermittently.
D)They were originally all of equal duration but most of them got eroded and are full of unconformities.

Question

Quizplus · Accepted Answer

The periods and epochs of the geologic time scale are of unequal lengths because they are based on unique environments or events in Earth's history that occur intermittently. For example, the duration of some periods may be based on the duration of a basin, while others may be based on the duration of an extinction event or an orogeny. Therefore, the lengths are not predetermined or uniform.

Why Are the Successive Periods and Epochs of the Geologic