Studies of Ice Movements on the Ward Hunt Ice Shelf by Means of Triangulation-Trilateration

A method is described by which accurate measurements of ice movements were performed on the Ward Hunt Ice Shelf at Ward Hunt Island. Geodimeter distance measure- ments and angular theodolite measurements were combined in a system of triangulation- trilateration in the form of a chain of quadrilaterals to achieve relative positioning accuracies of r 1 to 2 cm. for the survey markers drilled into the shelf ice. Shelf ice movements of 30 cm. with respect to solid ground were obtained between 1964 and 1965. The relative position change between the markers on shelf ice was less than 4 cm. Experience on this first known arctic application of the geodimeter are reported.