1. Berkson, J. M., and Clay, C. S., Geol. Soc. Am. Bull., 84, 1315 (1973).
2. Farrand, W. R., Proc. Twelfth Conf. Great Lakes Res., 12, 181 (International Association for Great Lakes Research, 1969).
3. Farrand, W. R., Mitt. Internat. Verein. Limnology, 17, 34 (1969).
4. Dell, C. I., Proc. Fifteenth Conf,. Great Lakes Res., 15, 361 (International Association for Great Lakes Research, 1972).
5. King, L. H., and MacLean, B., Geol. Soc. Am. Bull., 81, 3141 (1970).