Harrow and Hillingdon Geological Society
Geologist in the Arctic
A Geologist in the Arctic
Alaska is approximately ¼ the landmass of USA. In 1961, work was initiated to locate oil in the Brookes Range, which runs from east to west for about 700 miles, and also on the Arctic coastal plain. There was a series of overlapping camps about 35 miles apart. Excavation revealed Neolithic knapped flints of obsidian, which had been made into scrapers and arrowheads. This is an area of permafrost, about 2,000ft thick, which remains at or below freezing for 2 or more years. The Brookes range is snow-covered but was previously ice-free and has some remarkable peri-glacial phenomena, many showing typical hexagonal forms. There are pingoes or ice volcanoes, and alfeis which is ice grounded on shingle. These alfeis never melt but forms dams on the rivers. Caribou inhabit this area as it is mosquito free. The permafrost is of high ice content and can cause the pipeline to rupture. The arctic is climatically a desert with <7 inches of precipitation and snow like talcum powder.
All the buildings were prefabricated elsewhere and taken to Alaska. In winter the temperatures are -20 to -30º C.
The pipeline went from Prudhoe Bay to the Valdez terminal as this is an all year ice-free port. For about half of its length the pipeline is above ground and is designed to withstand earthquakes of up to 8.5 on the Richter scale. The pipe is 48 inches in diameter and carries insulation of aluminium 12 inches thick. The tundra also acts as a very good insulator. The temperature of the oil is 123º F, and the reservoir is located in perma-triassic sandstone 8-9.5 x 103 feet thick. In summer it is often 90-95º F but in winter, it drops to -60º F. There are roads from Fairbanks to Anchorage.
This was a fascinating talk with some lovely slides depicting spectacular glacial scenery. It was not too taxing on the brain and provoked a lot of questions.