Conglomerates and associated clastic rocks occur in western Ontario at intervals from Eagle Lake to Lake Savant, roughly 150 miles from southwest to northeast. The study of these sediments was begun in the summer of 1928 and continued in 1929 and 1932. In the vicinity of Sioux Lookout and Minnitaki Lake a detailed study of these rocks was made. The geologic map (Pl. 51, facing p. 504) covers the area investigated.
The writer was ably assisted in the field at various times by H. N. Johnson, of Halliday, North Dakota; W. M. Chappell, of the University of Washington, Seattle; C. E. Dutton, of the University of Minnesota; and D. L. Baker of New Haven, Connecticut. He is indebted to Dr. F. F. Grout, of the University of Minnesota, for many suggestions and criticisms, and to Oberlin College for a grant that partially defrayed the expense of the field work.