Short answers, pulled from the story.
A glacial period marks an interval of time spanning thousands of years within a larger ice age where temperatures drop significantly and glaciers advance across the landscape. Interglacials represent the warmer periods that exist between these cold phases.
The Quaternary period began approximately 2.6 million years before present. Within this timeframe, at least eight distinct glacial cycles have occurred in the last 740,000 years alone.
The Penultimate Glacial Period started about 194,000 years ago and concluded 135,000 years ago. This phase ended with the beginning of the Eemian interglacial.
Glaciations during the Last Glacial Maximum reached their peak extent about 26,500 BP. In North America, these ice sheets carried the name Wisconsin while Great Britain experienced a period known as Devensian and Ireland faced the Midlandian phase.
Changes in atmospheric carbon dioxide levels served as primary drivers for globally cold climates during glacials. Warm interglacials were influenced by shifts in ocean physical circulation patterns and biological productivity within oceans also contributed significantly to these climatic cycles.