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Himalayan Glaciers in Bhutan
This period includes two epochs, the Holocene and the Pleistocene, with the Holocene being the most recent and the Pleistocene the older one. The start of the Holocene can be traced to about 11.5 thousand years ago while the Pleistocene to about 1.8 million years ago.
The Pleistocene is actually what most of us call the Ice Age. Animals in the Pleistocene looked quite similar to those that we see today. To give you an idea, just imagine the animated creatures Manny and Ellie the Wooly Mammoths, Sid the Megatherium, Diego the Smilodon, Crash and Eddie the Opossums, and Scrat the sabertooth Squirrel from the movie bearing the same name (Ice Age).
If you’re not familiar with geologic time divisions, here they are: supereons are divided into eons, which are divided into eras, then periods, epochs, ages, and chrons.
The Quaternary Period is just one of three periods that make up the Cenozoic Era. The other two periods are the Neogene and Paleogene. In most cases, the two periods (Neogene and Paleogene) are combined to form what is known as the Tertiary Period.
The classification of the Quaternary Period was first proposed by Giovanni Arduino in 1759 upon discovering alluvial deposits in the Po River Valley, which is found in northern Italy. In 1829, Jules Desnoyers again pushed for the term upon discovering sediments in France’s Seine Basin that appeared to be younger than rocks found in the Tertiary Period.
Throughout geological times, plate tectonics have produced faults, which are large fractures in the Earth’s crust. In fact, in the San Francisco Bay area alone, which is home to frequent tremors, the faults underneath the city easily numbers to the hundreds.
Of these faults, geologists are most concerned with those known as Quaternary-active faults. That is, faults that slipped in the Quaternary Period. Older faults have the least likelihood of causing disastrous earthquakes. Quaternary-faults on the other hand, which are relatively fresh, are believed to possess the right conditions to spur great earthquakes in the future.
The Quaternary Period also saw frequent advances and retreats of glaciers (known as glaciation) that eventually formed geological features like the Great Lakes.
Want to learn about another period in geologic time? Try the Precambrian Period. There are only a few articles about the Precambrian period but we’ve got a few here in Universe Today:
Granite Rock
Ozone Layer
You may find more information about the Precambrian from the Michigan State University Department of Geography. There’s also some information about Precambrian rocks at USGS.
Check out Astronomy Cast. Episode 151 Atmosphere .
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