Quaternary Time Table
Older North American glacial research proposed four major glacial advances (Wisconsin, Illinoian, Kansan, and Nebraskan) during the Quaternary Period, and the Quaternary time scale was divided into the four glacial advances separated by three interglacials (Sangamon, Yarmouth, and Aftonian). More recent evidence suggests that there were many advances and retreats, and there is a trend toward dividing the Pleistocene into Late, Middle, and Early Pleistocene based upon new dating methods instead of glacial movement. Only the last glacial and interglacial are being retained as part of the Late Pleistocene.
|Epoch||Stage||Beginning date ka*|
|Holocene||10 to 12**|
|Middle Pleistocene||750 to 775|
|Early Pleistocene||1,650 or 2,480***|
* ka stands for kilo anno, or one thousand years. 10 ka would mean 10,000 years before the present, and 1,650 ka would mean 1,650,000 years before present.
** There is scientific debate on where to put this boundary, it appears at different ages around the world.
*** Two different times have been proposed for the international standard Pliocene-Pleistocene boundary. The problem is that neither of them are a clear marker throughout the world.