English

Adjective

interglacial

1. Of or pertaining to a period between ice ages

Derived terms

• interglacial optimum

See also

• interstadial

An interglacial is a geological interval of warmer global average temperature that separates glacial periods within an ice age. The current Holocene interglacial has persisted since the Pleistocene, about 11,400 years ago.

Interglacials during the Pleistocene

During the 2.5 million year span of the Pleistocene, numerous glacials, or significant advances of continental ice sheets in North America and Europe have occurred at intervals of approximately 40,000 to 100,000 years. These long glacial periods were separated by more temperate and shorter interglacials.

During the interglacials, one of which we are in now, the climate warmed to more or less present day temperatures and the tundra receded polewards following the ice sheets. Forests returned to areas that once supported the tundra vegetation. Traditionally, interglacials have been identified on land or in shallow epicontinental seas by their paleontology. Floral and faunal remains of species pointing to temperate climate and indicating a specific age are used to identify particular interglacials. Most used are mammalian and molluscan species, pollen and plant macro-remains (seeds and fruits). However, many other fossil remains may be helpful: insects, ostracods, foraminifera, diatoms, etc. More recently, ice cores and ocean sediment cores have provided more quantitative and better dated evidence for temperatures and total ice volumes.

Interglacials are a useful tool for geological mapping and also for anthropologists, as they can be used as a dating method for hominid fossils. .

Brief periods of milder climate that occurred during the last glacial are called interstadials. Most (not all) interstadials are shorter than interglacials. Interstadial climate may have been relatively warm but this is not necessarily so. Because the colder periods (stadials) have often been very dry, wetter (so not necessarily warmer) periods have been registrated in the sedimentary record as interstadials as well.

The oxygen isotope ratio obtained from deep sea cores and a proxy for average global temperature, is an important source of information about changes in the climate of the earth.

See also

• Snowball earth
• Greenhouse and Icehouse Earth
• Interstadial periods
• Milankovitch cycles

References