The nature and timing of early postglacial landscape change, central coast, British Columbia

不列颠哥伦比亚省中部海岸冰期早期景观变化的性质和时间

• 批准号: RGPIN-2017-03803
• 负责人: Lian, Olav
• 金额: $ 1.6万
• 依托单位: Fraser Valley
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=678903
• 关键词: nature; timing; early; postglacial; landscape

The history of landscape change along coastal British Columbia (BC) since the end of the last ice age (glaciation), about 15,000 years ago, is complex and poorly understood. This is because of several factors, including a relative sea level (RSL) that varied considerably from region to region during postglacial time, due to complex relationships between the depression of the earth's crust as a result of differential loading by glacial ice; the presence of a high-energy and variable wind and wave regimes that bring, or erode, sediment from the coast in a complex fashion; the sensitivity of coastal sedimentary landforms, such as modern and relict beaches and dunes, to short term changes in climate; and access many of the areas of interest are remote and can only be accessed by boat, helicopter, or by small amphibious aircraft. Gaining insight into the character of how the coastal landscape evolved since the last glaciation is important if predictions about how it will adjust as a result of predicted future climate change (e.g., rising global temperature and sea level, and increased coastal storm activity) are to be made. The BC coast has also been identified as a possible early migration route for the peopling of the Americas. There is new information that suggests that regions of the central coast where RSL change since the end of the last glaciation was minimal were areas of early and prolonged human settlement. There is also evidence that suggests that parts of the BC central coast were ice-free during the last and preceding glaciations. These regions would have served as places of refuge for plants and animals, and they would have spread from these places each time glaciation ended. It is therefore important to confirm the presence (in both time and space) of these refugia, and what survived in them, if the evolution of the landscape and the pattern of human migration and settlement is to be understood. Understanding the nature and timing of landscape change along the BC central coast is therefore not only of interest to geoscientists, but also to archaeologists and anthropologists, and the general public. This research program will investigate short and long-term changes to the coastal geomorphology of regions of the BC central coast, building on preliminary work done by others and by us on Calvert Island, with the aim of providing a more constrained (in time and space) record of landscape change. Landforms to be investigated are relict (raised) beaches dunes, and deltas that represent periods of transitory landscape stability and instability; special attention will be given to landforms that have been identified as having archaeological significance. Haida Gwaii will be revisited with the goal of gaining further evidence for the presence of biological refugia during the penultimate glaciation, which has so far been found at only one site.

自大约15,000年前的最后一个冰河时代(冰川)结束以来，不列颠哥伦比亚省(BC)沿海地区的景观变化历史是复杂的，人们对此知之甚少。与若干因素有关，其中包括：在冰川后时期，由于各地区的相对海平面差异较大，各地区的相对海平面差异很大，而且各区域的相对海平面也存在差异；由于冰川负载不同，地壳的凹陷形成了复杂的关系；高能多变的风浪制度使沿海地区的沉积物受到复杂的侵蚀；沿海沉积地貌，如现代的和残留的海滩和沙丘，对气候的短期变化非常敏感；很多受影响的地区都很偏远，只能乘坐船只、直升机或小型两栖飞机才能进入。如果要预测由于预测的未来气候变化(例如，全球气温和海平面上升以及沿海风暴活动增加)，沿海地貌将如何调整，就必须深入了解自上次冰川以来沿海地貌演变的特点。不列颠哥伦比亚省海岸也被确定为美洲人可能的早期移民路线。有新的信息表明，自上一次冰川结束以来，中部海岸RSL变化最小的地区是早期和长期人类定居的地区。也有证据表明，公元前中央海岸的部分地区在上一次和之前的冰川期间没有结冰。这些地区本来是植物和动物的避难所，每次冰川结束时，它们都会从这些地方扩散出去。因此，如果要了解地形的演变以及人类迁徙和定居的模式，重要的是确认这些避难所的存在(在时间和空间上)，以及在这些避难所中幸存的东西。因此，了解公元前中部海岸景观变化的性质和时间不仅对地球科学家感兴趣，而且对考古学家、人类学家和普通公众也是如此。这项研究计划将在其他人和我们在卡尔弗特岛所做的前期工作的基础上，调查不列颠哥伦比亚省中部海岸地区沿海地貌的短期和长期变化，目的是提供更受限制的(在时间和空间上)景观变化的记录。要调查的地貌是残留的(凸起的)海滩沙丘，以及代表短暂景观稳定和不稳定时期的三角洲；将特别注意已确定具有考古意义的地貌。海达瓜伊岛将被重新考察，目的是获得在倒数第二次冰川期间存在生物避难所的进一步证据，到目前为止，只在一个地点发现了冰川。