Measurements of the gross beta activity of firn samples taken from drillings in the region of the North Water polynya allow us to identify deposits of the radioactive Fall-out of 1963, due to a maximum of gross beta activity in a vertical profile. Drillings were made in the lower region of the accumulation area (Percolation Zone). The reference horizon of 1963 in this area is well marked by a concentration of deposits of radioactive fall out. This method of dating still enables us to determine the mean annual net accumulation since 1963.

Supplement to: Ambach, Walter; Müller, Fritz (1980): Determination of net accumulations from gross beta activity measurements in the North Water region. Polarforschung, 50(1/2), 1-7