T3 - Quaternary Geology

• • Quaternary began 2.58Ma (current geological period; before the Quaternary is was the Neogene)

  A) Holocene

  B) Pleistocene

  
• • Quaternary 'Ice age'; onset of global cooling leading to expansion of ice sheets at high-mid latitudes
  • phases of extensive glaciation (glacials) seperated with phases of warmer conditions with glacier retreat (interglacials)
  • in Quaternary 'Ice age', conditions not uniformly cold (varied climate over short time scales); oscillations between glacials and interglacials as climate was colder/warmer
• • over past 600,000yrs, 6 pronounced phases of glaciation followed by interglacials when global ice volume decreased; global ice volume gradually builds up during glacials but decreases rapidly at start of interglacials
  • most of Pleistocene had colder conditions (greater volume of ice than today) and interglacial warmth similiar to Holocene but relatively short
  • over past 1Ma, todays's climate only occured for 10% of time (mostly it has been colder with more extensive ice sheets/glaciers)
• • Stadial Period - relatively short phases of intense cold that occured during the last glacial (and during previous glacials) - ice sheets increase in size + tundra-type vegetation replace woodland-type across mid-latitude areas in northern hemisphere.
  • Interstadial Period - brief phases of relative warmth during glacials (lasts around 500-2,000yrs) - temporary ice sheet retreat + northward spread of woodland (but phases not long enough to be classed as interglacial).