Antarctic ice thickness sounding, and the Commonwealth Trans-Antarctic Expedition during the IGY

I try to be careful about expanding the scope of my two topical collections (IGY and North American earthquakes). This is a short explanation of the decision to expand of my IGY collection to include the Commonwealth Trans-Antarctic Expedition of 1955–1958.

I was catching up on reading some old issues of magazines and journals, and I came across an article entitled "How Thick Is Antarctic Ice, and What Is Underneath? Scientists used electromagnetic fields to determine the thickness of fast ice," by Saima May Sidik, in Eos, 104, published by the American Geophysical Union,  22 February 2023.

This news article describes a paper by Langhorne et al. that provided more reliable estimates of Antarctic fast ice (sea ice that is "fastened" to the coastline, to the sea floor along shoals, or to grounded icebergs - see figure below) thickness by using a technique of airborne geophysics, specifically electromagnetic induction sounding. A sensor called a “bird” is towed beneath the aircraft at an altitude of 15 meters above ground level. A magnetic field is transmitted through the ice into the conductive seawater  below which then induces electric currents that the bird can detect. The resulting data are used to infer the ice thickness. This technique has several advantages over previous methods: a wider geographic range than drilling into the ice; penetration of saline sea ice, unlike radar; and more certain estimates than satellites.

Some of the most common sea-ice related features, including  fast ice. The bear provides an approximate scale for this scenario (Wikipedia)

The researchers used the system to survey a 700-km-long section of coast in the Ross Sea, home to the Scott Base, McMurdo, and Zucchelli research stations (see a map of the stations in this post). The area is known for its floating glaciers and ice shelves which are stabilized by fast ice. Fast ice in the region was found to be typically 2-3 meters thick. 

A search revealed that a stamp issued in 2022 by New Zealand's Ross Dependency depicts this method (Scott NZ-RO L177), showing a helicopter towing a bird (see right). This image is from colnect, not my collection. This stamp is one of four stamps comprising a Science on Ice miniature sheet.

Determining Antarctic ice thickness was also a goal of the IGY, although more for the continental ice sheet rather than for fast ice. For example, right after I left off my reviews in this blog of the IGY Bulletin with Number 9, issue Number 10 started with an article on "IGY Antarctic oversnow traverses." It describes three major oversnow traverses planned by the U.S. IGY Committee for the 1957-58 summer season, shown on the map below.

Traverses across the Ross Ice Shelf from the Little America Station, over parts of Marie Byrd Land and the Ellsworth Highland from Byrd Station, and across the Filchner Ice Shelf and parts of Edith Ronne Land from Ellsworth Station.

On these traverses, coring along with ground-based geophysical methods of seismics, gravity, and geomagnetism were used to infer continental ice sheet thicknesses of as much as 10,000 feet (3000 m).

Simplified cross-sectional profiles of the continental ice sheets in Greenland and Antarctica (https://opentextbc.ca/geology/chapter/16-2-how-glaciers-work/)

Scott GB-AT 47, my collection

I wondered if there were any IGY stamps that focused on Antarctic ice thickness. Another search in colnect led me to such a stamp on seismic depth sounding from the British Antarctic Territory (Scott GB-AT 147, shown at right), issued in 1988 to commemorate the 30th anniversary of the Commonwealth Antarctic Expedition of 1955-58. This was from a four-stamp series which I then bought. 

The other three stamps in the series, shown here, have themes of the aurorae, aircraft, and a Sno-cat.

I also bought this first day cover with cachet including all four of the stamps.

Cover showing all four stamps from the BAT 1988 set commemorating the 30th anniversary of the Commonwealth Trans-Antarctic Expedition (scanned from online, since my purchase has not yet arrived).

I decided this Expedition and its anniversary would be legitimate components of my IGY collection. According to Wikipedia:

The Commonwealth Trans-Antarctic Expedition (CTAE) of 1955–1958 was a Commonwealth-sponsored expedition that successfully completed the first overland crossing of Antarctica, via the South Pole. It was the first expedition to reach the South Pole overland for 46 years, preceded only by Amundsen's expedition and Scott's expedition in 1911 and 1912.

It was headed by British explorer Vivian Fuchs, with New Zealander [mountaineer] Sir Edmund Hillary leading the New Zealand Ross Sea Support team. The New Zealand party included scientists participating in International Geophysical Year [emphasis mine] research while the British team were separately based at Halley Bay.

Route map of the Commonwealth Trans-Antarctic Expedition (Reed Gallery)

The British Antarctic Territory (consisting of the South Shetland Islands, South Orkney Islands and the Antarctic Peninsula with a sector of the continent extending to the South Pole) issued stamps in 1963, 1966, 1969, 1971, 1972, 1973, 1974, and then annually since 1977. It's interesting that the BAT only issued these four Antarctic stamps in 1988, the lowest number in any one year. A smoothed graph I made of the issuances per year shows a 5-year decline starting after 1983, then a general rise until 2012 and another decrease since then. Whatever significance there may be in these trends is beyond me.

Issuance of stamps by British Antarctic Territory. Data from Colnect.

More on related covers in future posts.