The stratigraphy and structure of the area of the Colville north of Umiat was studied by U. S. GeologicaI Survey Party No. 1 during the period of May 31 to July 19, 1947. The. party, consisting pf two geologists, a cook, and a "weasel" mechanic, left Umiat in two "weasels”. The weasels were used to transport the party and equipment from camp to camp, and also made it possible for the geologists to work as far as 15 to 20 miles out from a camp in one day. A ten-foot canvas-boat was carried along. During most of the month of June even the smaller tributaries to the Kogohokruk carried enough melt and run off water to make them navigable in the 10-foot boat. The party returned to Umiat on June 23, after traversing both the Kikiakrorak and the Kogohokruk Rivers, and several smaller tributaries to the Kogohokruk.