ROSS ICE SHELF AS GLACIER STUDY

Press, Volume CI, Issue 29753, 21 February 1962, Page 11

ROSS ICE SHELF AS GLACIER STUDY

The Ross Sea ice shelf is being studied as a model glacier in an attempt to arrive at a formula for the rate of ice flow which can be applied to any glacier. The work of the four-man University of Michigan team of glaciologists was described by the English leader, Dr. C. W. M. Swithinbank. in an interview in Christchurch. The Ross shelf, the largest sheet of floating ice in the world, was ideal for the task, he said. The floating ice had no appreciable friction at the bottom. With a land glacier this friction was unknown. The temperature at the bottom of the ice sheet was another known factor, being the freezing point of sea water. The party has been measuring the quantities of ice involved —the thickness, the inflows which form the glacier, and the rate of flow to sea. It is measuring how much ice in the shelf has come from the glaciers along the western edge, how much from Marie Byrd Land to the east and how much comes from surface snow. This is found by inserting markers around the ice shelf, then later measuring the movement and snow depth. Some 1800 markers left between 10 and 100 miles of the sea edge last year could be measured next year, said Dr. Swithinbank. This year his party has been measuring the huge valley glaciers along the 600- : tnde west side of the shelf.

These include some of the world’s biggest and fastest flowing. One measures 100 miles by 20 miles. From the data w'hich is gained, it is hoped that a flow law can be worked out which can be applied to glaciers. The flow law was like the viscosity of a motor oil, being concerned with thickness, temperature and movement, he said. With this information, glaciologists will be able to predict unknown data about glaciers while knowing only some factors. For instance, if the slope and rate of flow are known, they will be able to predict the thickness. Asked why a smaller ice shelf had not been chosen to arrive at the same results with less apparent effort, Dr Swithinbank said the Ross shelf was the handiest to the American base and also, because of its size, the most interesting. The flow measurements formed the main work but his party was also exploring other fields, he said. As it travelled they measured at intervals the ice temperature at a depth of 30ft in areas without melting. This temperature changed very little throughout the year and represented within one degree the mean annual air temperature. The warmest area for the latitude in Antarctica was along the west coast of the ice shelf. In summer the temperature was between 25 and 32 degrees, said Dr. Swithinbank