May 17, 2017

Glacier Benito Journal: Prologue–1972 to 2011

Posted by larryohanlon

See the other posts from this expedition here

By Martin Sessions

A dream turns into an obsession. Finally an obsession is resolved. How did it happen?

Martin in 1972 and 2017.

In 1971, I was lucky enough to be selected as a member of the 1972/73 British Joint Services Expedition to Chilean Patagonia led by Crispin Agnew. My tasks were to undertake the glacier and weather studies of the expedition. The expedition´s base camp was in Kelly Inlet (Abra Kelly).

Charles Darwin, in Volume III of ‘Voyages of the Adventure and Beagle’, mentioned that glaciers reached the head of Kelly Harbour as reported by Captain King following Captain Stokes visit there in 1828. He remarked on the fact that glaciers here descended to sea level at Latitude 47ºS, compared with Norway where the first glaciers to reach sea level were at 67ºN, a 20º difference. The glaciers that Captain Stokes saw would have included Glacier Benito.

Glacier Benito appeared to be the best glacier to study in the area. It had its own basin, was of a significant size and was accessible from Kelly Inlet. So over the course of four months, ablation was measured, stake movement was monitored, snow line observed and many black and white panoramas taken with a Rollicord camera. One other important task was undertaken – to measure the surface profile across the glacier with a surveyor’s instrument called a ‘Level’ near the end of season snow line, 15 kilometres (km) up glacier from its terminus or ‘snout’. The surveyed profiles were called the ‘Levels’ after the instrument that was used for the task. This task has only been undertaken in one other Patagonian glacier before the advent of satellite data and aerial photographs with accurate glacier contours.

Drilling Holes for Stakes – Glacier Benito November 1972.

In the 1990s, this was a dream but a walk on Franz Joseph glacier in New Zealand which coincided with an e-mail from Charles Warren of St Andrews University indicated there was a possibility of realising the dream. After discussions with Neil Glasser (Aberysthwyth University), Stephan Harrison (Exeter University) and Vanessa Winchester (Oxford University) together with an investigation visit to Region XI hosted by Graham Hornsey, the dream came closer to becoming true.

The 2007 Expedition, with Olaf Wuendrich of ColibriVentura as guide, undertook important survey work in fixing the lower stake network but access to the Levels was too difficult because of the emergence of additional icefalls as the glacier thins and steepens. An important outcome of this expedition was Vanessa Winchester’s paper Post-1850 changes in Glacier Benito, North Patagonian Icefield, Chile.


Survey Work – Glacier Benito March 2007

Another attempt was made in 2011 using an overland route from Laguna San Rafael with Peter and Olaf. We tried another route up the glacier but ran out of time. The walkout was challenging yet exhilarating for the two 60+ year olds as we ‘pack rafted’ many kilometres down the Andree river, across Kelly Inlet, around Glacier San Quintin, through marshland, down Rio Tadeo and finally up Rio Negro. However I realised in the final stages that I had little hope of tying the Levels to the world grid and providing a unique record of the thinning of Glacier Benito over 44 years until . . . .

Survey Work – Glacier Benito March 2011.

When we were at Laguna San Rafael waiting for a boat outback to Puerto Chacabuco, we observed a helicopter moving around the airfield. The helicopter was supporting a Japanese Professor in his quest to find a rare insect on the icefield. We were given a lift in the helicopter as it returned to its base in Puerto Chacabuco for the night.

Helicopter at Laguna San Rafael March 2011.

The cogs started to turn and a dream turned into an obsession! The obsession is illustrated below in Google Earth . . . .

The Levels superimposed on Glacier Benito in Google Earth

 — Next: Planning and Preparations —

This post was originally published here

Martin Sessions was born in Kenya in 1948 but educated in England, finishing up with a degree in Engineering at Cambridge University (Pembroke College). For 28 years, he served in the Royal Navy as an Engineer Officer before migrating to Australia where he is an engineering consultant in Canberra. His first expedition was to Koldukvislarjokull in the North West corner of Vatnajokull, Iceland in 1970. Then followed expeditions to Chilean Patagonia (1972/73) and Liverpool Land, Greenland (1977). Finally he made expeditions to Glacier Benito in 2007, 2011 and 2017 to capitalize on work undertaken there in 1972/73.