From the time of its discovery until the latter years of the nineteenth century Antarctica remained a terra incognita to the geologist, but in the early years of this century the Falkland Islands Dependencies attracted some academic interest, particularly from geologists. Undoubtedly this was mainly due to the fact that the Dependencies occupy one of the more accessible parts of the Antarctic continent and also bear a close geological relationship to South America.

In August 1946 John Tonkin, navigator at the Falkland Islands Dependencies Survey station on Stonington Island in Marguerite Bay, Graham Land, was leading a team of dogs half a mile from the station. As the path was a well-trodden one he was not wearing skis. Four other men were in the party. He was walking close in front of the lead dog when suddenly he disappeared down a hidden crevasse. Fortunately it was a very narrow one and he stuck about 40 ft. down, jammed by the thickness of his body, and with his legs hanging free. Other men were called from the station and came to his rescue with rope, but no pulley block. First, ropes with loops on their ends were lowered, and Tonkin managed to put his arms through the loops, and so acquire some feeling of security. The narrowness of the crevasse meant that a rescuer had to be lowered spread-eagled with his weight taken in loops of rope clove-hitched around the instep. It also prevented the free use of an ice axe, and the process of chipping Tonkin free was carried out slowly with the ferrule and spike sawn off the end of an ice axe. Two hours after the accident Tonkin was hauled to the surface by means of the original ropes looped round his arms. The strain of his weight on the ropes damaged the nerves of his arms, and a partial paralysis resulted for several months.