ACKNOWLEDGEMENTS 
Our understanding of the spring break-up of the Mackenzie 
River has been greatly increased by the aerial surveys made in 
1972, 1973 and 1974. The flying hours on a Beech G-18-S were 
provided by the Polar Continental Shelf Project, Department of Energy 
Mines and Resources. Thanks are due to Mr. George Hobson, Coordinator 
of the P.C.S.P., for this cooperation. 
REFERENCES 
Ferguson, H.L. and Cork, H.T. 1972. The use of satellite photographs 
to determine the time of freeze-up and break-up of Canadian 
Lakes. Proceedings of the First Canadian Symposium on Remote 
Sensing, Ottawa, February 1972. pp. 269-280. 
Golding, D.L. 1974. Snow cover and melting snow from ERTS Imagery. 
Canadian Surveyor, Vol. 28, No. 2, pp. 128-134. 
McClain, E.P. 1973. Quantitative use of satellite vidicon data for 
delimiting sea ice conditions. Arctic, Vol. II, No. 1, pp. 44-47.