The Younger Dryas (YD) cold event was discovered in Denmark by Hartz and Mithers in 1904 and the term coined by Hartz in 1912. It was identified as a lacustrine clay bed containing plant macrofossils of an Arctic flora, including Dryas octopetala, and lying between Allerød and Holocene gyttjas containing a warmer flora with birch trees. The YD is unique in the sense that it is the largest and most abrupt climate change on Earth since the Last Glacial Maximum and thus within the reach of radiocarbon dating. Yet, I consider it is part of a regular Dansgaard‐Oeschger event. The term has been used for a climate event and for lithostratigraphical, biostratigraphical and several other stratigraphical units. I prefer using it as a geochronological and chronostratigraphical unit, i.e. that the YD represents a specific period of geological time and the rocks and sediments formed during this period. In the type area of southern Scandinavia, the YD chron represents the age and duration of the cold event.

中文翻译：

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Younger Dryas的发现，并对该术语的当前含义和用法进行评论

年轻的树蛙（YD）寒冷事件是1904年在丹麦由Hartz和Mithers在丹麦发现的，该术语由Hartz在1912年创造。它被确定为湖相黏土层，其中包含北极植物区系的植物大化石，包括八角鱼。，位于Allerød和全新世gyttjas之间，那里有桦树的温暖植物群。YD是唯一的意义，因为它是自上次冰川最大值以来地球上最大，最突然的气候变化，因此在放射性碳测年的范围内。但是，我认为这是Dansgaard-Oeschger定期活动的一部分。该术语已用于气候事件以及岩石地层学，生物地层学和其他几个地层学单位。我更喜欢将其用作地质年代和年代地层单位，即YD代表特定的地质时期，以及在此期间形成的岩石和沉积物。在斯堪的纳维亚半岛南部的类型区域中，YD chron代表冷事件的年龄和持续时间。