Oxygen isotopic ratios in the dating of ice cores

10-Dec-2019 22:41 by 7 Comments

Oxygen isotopic ratios in the dating of ice cores

In addition, cold sinking air over the ice sheets created strong down-flowing katabatic winds, drying land near the glaciers.

However, no decision was made to equate the beginning of the Pleistocene Epoch to the beginning of the Quaternary Period, and indeed the very status of the Quaternary as a period within the geologic time scale had come into question.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 kilometres thick have covered vast areas of the continents in temperate areas.However, since the 1950s the marine record has become more useful because of its greater continuity and preservation.Marine cores may contain microscopic fossils of single-celled organisms called foraminifera, whose shells contain a record of water temperature and composition as stable isotopes of oxygen and carbon.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.

Continental ice sheets formed and extended into temperate latitudes numerous times in the Quaternary, but the terrestrial record of these events is somewhat incomplete.

The traditional view is that of only four major glacial periods, or “ice ages.” They have been correlated to one another in a rather simple manner and are reflected in the names of some geologic units.

Ice shelves similar to those seen today in the Ross and Weddell seas of Antarctica are postulated to have existed in the Norwegian Sea and the Gulf of Maine and were likely in many other settings.

High ice and domes of cold high-pressure air displaced the polar jet streams, steering storm tracks south to the glacial margins and beyond.

Rather, it spread from the centres of Canada, Scotland, Sweden, and possibly northern Russia.