The Younger Dryas is so called because it corresponds, in the pollen record from Europe, to the latest (i.e. youngest) appearance of the Dryas octopetala pollen, an alpine flower in regions that are now far from alpine. It marks a clear period towards the end of the last ice age when the warming trend of the deglaciation in Europe particularly was interrupted for a period of about 1300 years before it got going again. There were clear glacier advances during this time and the moraines can be seen very clearly all around Europe and Scandinavia.
The clues to what caused this remarkable, if temporary, turnaround have always lain in assessing its spatial extent, the exact timing and correspondence with other events. Two recent papers have shed some welcome and potentially controversial light on the subject.