This study of lateral erosion rates by comparison of aerial photographs was undertaken at the request of D. M. Culbertson, hydraulic engineer, U.S. Geological Survey, Menlo Park, Calif., and preparatory work in Alaska (during June 1-18, 1971) was done with the cooperation of Harry Hulsing, district chief, Alaska District. Examination of river crossings between the Yukon River and Prudhoe Bay was done by helicopter, for the use of which I am indebted to Giles McDonald of the Bureau of Land Management. Most of the crossing sites described here were examined in the field, in too brief a time to permit quantitative measurements but long enough to be of much assistance in interpretation of the aerial photographs. Location of the earlier photographs with reference to the terrane was difficult because of the inaccuracy of existing index sheets, but it was greatly facilitated by Ray Krieg of the R & M Engineering Geological Consultants in Fairbanks and by personnel of the Alyeska Pipeline System Office in Anchorage. This report was prepared at Washington University in St. Louis, Mo., with support by Research Grant 8623-EN, Airphoto interpretation of the form and behavior of alluvial rivers, from the U.S. Army Research Office in Durham, N. C.
