Ice Margin Dynamics Research Articles

Ice Age people of North America: environments, origins, and adaptations

This volume provides an up-to-date summary of important new discoveries from Northeast Asia and North America that are changing perceptions about the origin of the First Americans. Even though the peopling of the Americas has been the focus of scientific investigations for more than half a century, there is still no definitive evidence that will allow specialists to say when the First Americans initially arrived or who they were. The nineteen papers collected here provide regional archaeological syntheses and address such topics as ice marginal dynamics, the impact of plant nutrients in glacial margins, and periglacial ecology of large mammals. The concluding chapter discusses conceptual frameworks used to explain the peopling of the Americas. This volume provides an up-to-date summary of important new discoveries earlier than ten thousand years old from Northeast Asia and North America that are changing our perceptions about the origin of the First Americans. It offers a detailed compendium of late-Pleistocene Paleoamerican archaeological records that can serve as a foundation of existing knowledge in this field and for creating the next generation of models that seek to explain the peopling of the Americas.

Retreat of a tidewater margin of the Laurentide ice sheet in eastern coastal Maine between ca. 14 000 and 13 000 14C yr B.P.

Ice-margin retreat, glacial processes, and associated marine environmental conditions were investigated along a tidewater margin of the Laurentide ice sheet in eastern coastal Maine. The ubiquitous presence of recessional moraines that typically show crosscutting relationships indicates that numerous stillstands and readvances interrupted net ice-margin retreat. Commonly, moraines exhibit changes in orientation associated with elevation changes, suggesting topographic control on retreat. Till, glaciofluvial facies, and glaciomarine sediment are the dominant components of the moraines. These sediments show that the ice terminated in the sea and that glacial meltwater played a key role in their deposition. The most continuous landforms in the study area are the Pond Ridge moraine and Pineo Ridge moraine system. Both landforms crosscut older moraines and contain ice-shove features, and crosscutting of moraines exists within the Pineo Ridge moraine system, indicating that the ice sheet readvanced during their formation. The Pond Ridge moraine and Pineo Ridge moraine system are straighter across elevation changes, compared to other moraines in the area, implying that during their formation, topography had less of a destabilizing influence on ice-margin dynamics. Foraminifera, Ostracoda, and mollusk species in ice-proximal and ice-distal glaciomarine sediments indicate that arctic to subarctic climatic conditions existed during deglaciation. Despite the persistence of a cold environment, 20 km of net ice-margin retreat occurred between ca. 14 000 and 13 000 14 C yr B.P., mostly in contact with the sea.

A Jökulhlaup Near Søndre Strømfjord, West GreenLand, and Some Effects on the Ice-Sheet Margin

AbstractOn 19 and 20 August 1984, an ice-marginal lake drained through a subglacial tunnel beneath the ede of the Greenland ice sheet, discharging about 22.3 × 106 m3 of water in less than 19 h. The event, which may occur annually, modified ice-margin dynamics at the lake site and along a 3 km stretch of ice margin 11 km down-stream.

A Jökulhlaup Near Søndre Strømfjord, West GreenLand, and Some Effects on the Ice-Sheet Margin

Abstract On 19 and 20 August 1984, an ice-marginal lake drained through a subglacial tunnel beneath the ede of the Greenland ice sheet, discharging about 22.3 × 106 m3 of water in less than 19 h. The event, which may occur annually, modified ice-margin dynamics at the lake site and along a 3 km stretch of ice margin 11 km down-stream.