Investigation of Stratigraphic Manifestations of Younger Dryas Climate at Paleoindian Sites in North America

大约11,000年前，北美的一大批大型动物在短时间内灭绝，科学家们希望了解其原因。已经提出了两种主要的理论：一种是气候变化和伴随的植被变化。另一本书指出了古印第安人猎人和采集者的存在，并认为狩猎是主要原因。在他之前的工作中，Vance Haynes博士已经确认了在美国西部、西南部和高平原的许多地点都存在着一种独特的黑色有机地层。在如此大的区域上找到如此清晰的地平线是极其罕见的，它的存在意味着一次重大的气候事件。与克洛维斯文化相关的文物被发现在地平线下，但永远不会在地平线之内或之上。来自后续福尔瑟姆组的石器只出现在地平线或地平线以上。这一事实导致海恩斯博士推测，有机层实际上是跨地点同步的，并且是在非常短的时间内沉积的。他将这一层与年轻的仙女座降温事件联系在一起，这是一个重大的气候变化时期。他还指出，这恰逢动物群灭绝最严重的时期。不幸的是，有机土壤层的年代并不准确，在NSF的支持下，海恩斯博士将参观一系列包含地平线的遗址，这些遗址也因为它们包含的考古和古生物材料而具有重要意义。他将记录地层层序，并收集用于放射性碳测年的成套材料。特定的有机化合物将被分离出来进行稳定同位素分析，以确定C3与C4植被的相对数量。通过这种方式，花的变化既可以被记录下来，也可以被记录下来。这项研究很重要，因为它将提供北美过去气候和环境变化的准确日期。这将完善理解人类行为变化和动物灭绝的框架。

Approximately 11,000 years ago a wide range of North American large fauna went extinct over a short time period and scientists wish to understand the cause. Two main theories have been proposed: one invokes climate change and accompanying vegetation shifts. The other notes the presence of Paleoindian hunters and gatherers and sees hunting as the primary cause. In his prior work Dr. Vance Haynes has recognized the presence of a distinct dark organic strata which is present in many sites in the US West, Southwest and High Plains. It is extremely rare to find such a well defined horizon over this large an area and its presence implies a major climatic event. Artifacts associated with the Clovis culture are found under the horizon but never within or above it. Stone tools from the succeeding Folsom group occur only in or above the horizon. This fact leads Dr. Haynes to speculate that the organic layer is in fact synchronous across sites and was deposited in a very short time period. He associates the layer with the Younger Dryas cooling event, a period of major climatic change. He also notes that this coincides with a period of maximum faunal extinction. Unfortunately the organic soil horizon is not well dated and with NSF support Dr. Haynes will visit a series of sites which contain the horizon and are also important because of the archaeological and paleontological materials they contain. He will record the stratigraphic sequence and collect suites of materials for radiocarbon dating. Specific organic compounds will be isolated for stable isotope analyses to determine relative amounts of C3 vs. C4 vegetation. In this way floral change can be both noted and dated. This research is important because it will provide precise dates for past climate and environmental change in North America. This will refine the framework for understanding changes in both human behavior and faunal extinction.