Quaternary Period

by Ashton

Major geologic events

Thick glaciers advance and retreat over much of North America and Europe, parts of south America and Asia, and all of Antarctica. Quaternary, in the geologic history of Earth, a unit of time within the Cenozoic Era, beginning 2,588,000 years ago and continuing to the present day. The Quaternary has been characterized by several periods of glaciation (the “ice ages” of common lore), when ice sheets many kilometer thick have covered vast areas of the continents in temperate areas. During and between these glacial periods, rapid changes in climate and sea level have occurred, and environments worldwide have been altered. These variations in turn have driven rapid changes in life-forms, both flora and fauna. Beginning some 200,000 years ago, they were responsible for the rise of modern humans.

Climate

Scientists have evidence of more than 60 periods of glacial expansion interspersed with briefer intervals of warmer temperatures. The entire Quaternary Period, including the present, is referred to as an ice age due to the presence of at least one permanent ice sheet (Antarctica); however, the Pleistocene Epoch was generally much drier and colder than the present time.

Although glacial advancement varied between continents, about 22,000 years ago, glaciers covered approximately 30 percent of Earth’s surface. Ahead of the glaciers, in areas that are now Europe and North America, there existed vast grasslands known as the “mammoth steppes.” The mammoth steppes had a higher productivity than modern grasslands with greater biomass. The grasses were dense and highly nutritious. Winter snow cover was quite shallow.

Animals

These steppes supported enormous herbivores such as mammoth, mastodon, giant bison and woolly rhinoceros, which were well adapted to the cold. These animals were preyed upon by equally large carnivores such as saber toothed cats, cave bears and dire wolves.

The latest glacial retreat began the Holocene Epoch. In Europe and North America the mammoth steppes were largely replaced by forest. This change in climate and food resources began the extinction of the largest herbivores and their predators. However climate change was not the only factor in their demise; a new predator was making itself known.

Intresing

One significant outcome of the recent ice age was the development of Homo sapiens. Humans adapted to the harsh climate by developing such tools as the bone needle to sew warm clothing, and used the land bridges to spread to new regions. By the start of the warmer Holocene epoch, humans were in position to take advantage of the favorable conditions by developing agricultural and domestication techniques. Meanwhile, the mastodons, saber-toothed cats, giant ground sloths and other megafauna that reigned during the glacial period went extinct by its end.

predators

Animals were preyed upon by equally large carnivores such as saber toothed cats, cave bears and dire wolves. The latest glacial retreat began the Holocene Epoch.