Abstract/Description or Keywords |
The oldest radiocarbon-dated sediment on Brooks Peninsula is a mudflow deposit containing wood dated at 30,800+/-510 BP (GSC-3449). Pollen collected from the sediment indicates that the climate at the time of deposition was cooler than present and possibly denotes climatic deterioration accompanying the beginning of the Fraser Glaciation on the peninsula. During the early stages of the Fraser Glaciation, Brooks Peninsula was subject to an extended period of cirque glaciation that probably commenced prior to 25,000 years ago and continued until sometime after 20,000 BP. Geological evidence indicates that at the Fraser maximum, about 15,000 years ago, ice covered low to mid elevations, but the high peaks and mountain ridges on the peninsula stood as nunataks above the ice surface. Estimates of the size of the ice-free area range from 7 km2 to 9 km2. The peninsula, located on the western margin of the ice front, a few tens of kilometres from the open sea, is tentatively thought to have a local climate modified by maritime air at this time. Thus, these ice-free areas may have been able to support biotic communities. Deglaciation of Fraser ice commenced prior to 12,250+/-790 BP (WAT-942). The maximum observed level of marine inundation during the close of this glaciation was 20 m above mean sea level. Sea levels during the early Holocene are unknown. However, during the past 4000 years, the peninsula has been rising relative to the sea at an average rate of 1 mm to 2 mm per year. Most of this uplift is attributed to tectonic forces. |