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CHAPTER 3 - Continental Shelf Geomorphology and Relief-Forming Processes
Published online by Cambridge University Press: 06 December 2010
Summary
Those who have studied the Antarctic from ships are aware of the inaccuracy of bathymetric charts, especially for the continental shelf. A general “rule of thumb” for ship captains is to avoid waters less than 100 m in depth. Several ships ignoring this policy have met with disaster, most recently the Argentine tour vessel, Vaja Parizo.
Bathymetric data are scarce to absent in many areas, and existing data may date back to the early part of the twentieth century. Even more recent bathymetric charts include data with poor navigational control. Extremely rugged topography, including rock pinnacles that rise to within meters of the sea surface, characterize the inner shelf and inland waters, and these are especially poorly charted. It is not uncommon to discover that an island or the coastline is located 1 to 2 km away from its charted position.
Until the late 1980s, ships working in Antarctic waters relied on satellite navigation systems and older forms of navigation. Accuracy varied from hour to hour and from year to year, depending on the number and locations of satellites in orbit. At their very best, these systems did not provide the accuracy needed to map bathymetric irregularities on the inner continental shelf. This has changed with the advent of the Global Positioning System (GPS), but data acquisition is slow. It will be many years before reliable charts are available, particularly for ice-covered regions.
Several countries have their own bathymetric charts that tend to emphasize areas where research stations are located. Attempts to integrate existing data from different sources have been directed toward compiling regional bathymetric maps. These maps provide the primary data set for examining Antarctica's seafloor relief.
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- Antarctic Marine Geology , pp. 58 - 88Publisher: Cambridge University PressPrint publication year: 1999