Science. 1970 Jun 19;168(3938):1449-50. doi: 10.1126/science.168.3938.1449.
A radiocarbon-dated pollen diagram from a depression near the end of the southeast arm of Yellowstone Lake, Wyoming, records the vegetation sequence from the retreat of Late Wisconsin (Pinedale) ice to the present time. The tundra Picea-Abies-Pinus albicaulis (spruce-fir-whitebark pine) parkland vegetation inferred during late glacial time changed rapidly to a Pinus contorta (lodgepole pine) forest shortly before 11,550 carbon-14 years ago, suggesting a warming trend at that time. The Pinus contorta forest persisted with minor modification throughout postglacial time.
怀俄明州黄石湖南部支臂尽头附近一处洼地的放射性碳定年花粉图记录了从晚期威斯康星冰期（派恩代尔冰期）后退到现在的植被序列。推断在末次冰期后期，苔原云杉-冷杉-白皮松（云杉-冷杉-白松）开阔地植被迅速转变为 11550 年前的花旗松（西部铁杉）森林，表明当时存在变暖趋势。花旗松森林在整个后冰期几乎没有变化地持续存在。
