Origin of Species, by Charles Darwin

Chapter X:
On the Imperfection of the Geological Record

On the absence of intermediate varieties at the present day — On the nature of extinct intermediate varieties; on their number — On the vast lapse of time, as inferred from the rate of deposition and of denudation — On the poorness of our palaeontological collections — On the intermittence of geological formations — On the absence of intermediate varieties in any one formation — On their sudden appearance in the lowest known fossiliferous strata — Antiquity of the habitable earth.