The second period of the * Cenozoic era from two million years ago to the present day. It is divided into the Pleistocene and Holocene (Recent) epochs. At its commencement, the climate was cool and temperate and there were four glacial periods, the evidence for which is borne out by the distribution of fossils. Many plants and animals became extinct. In the Holocene epoch, beginning about 10 000 years ago, the rise of civilization saw the origin of crop plants and their associated weeds. See geological time scale. |
