THE ROUTE EXPLORED. 101 



Lake Yukon — P 



Sediments 147 



Origin of the Lake 147 



Existing Glaciers 148 



Observations at Chilkoot Pass and about Lynn Canal 148 



Absence of Debris on the Glaciers : 15] 



Fan -shaped Terminals 152 



Recession of Glaciers about Lynn Canal 152 



Distribution of Glaciers in Alaska and accompanying Climatic Con- 

 ditions 152 



Discussion 155 



Index . 157 



Introduction. 



In the spring of 1889, the U. S. Coast and Geodetic Survey organized 

 and equipped two parties in San Francisco, Cal., for the purpose of estab- 

 lishing the position of the boundary between Alaska and the North West 

 Territory of Canada. These parties were in charge of J. E. McGrath and 

 J. H. Turner, officers of that survey, and had for their destination localities 

 on the Yukon and Porcupine rivers respectively, where those streams cross 

 the 141st meridian. 



Through the courtesy of the Superintendent of the U. S. Coast and Geo- 

 detic Survey, the Director of the U. S. Geological Survey was invited to 

 send a representative with the boundary survey parties for the purpose of 

 making geological observations in Alaska. This duty was assigned to me, 

 and a record of such observations as the character of the journey undertaken 

 enabled me to make is presented in the following pages. 



The expedition sailed from San Francisco on the steamship "Bertha" 

 June 14, 1889, and reached Iliuliuk, Unalaska island, June 27. We re- 

 mained at Iliuliuk four days ; our effects having then been transferred to the 

 steamship "St. Paul", we sailed for St. Michaels June 30, and, crossing Beh- 

 ring* sea, reached there July 7. We remained there until July 14, when, 

 all arrangements for ascending the Yukon having been completed, the final 

 stage in our journey was begun. The ascent of the river was made in the 

 stern-wheeled steamboat "Yukon", belonging to the Alaska Commercial 

 Company and built especially for the navigation of the rivers of Alaska. 



Our voyage up the Yukon was slow but did not allow much time on shore. 

 No stops were made except to obtain wood or provisions until arriving at 

 Fort Yukon, and such brief opportunities as were available for land excur- 

 sions were frequently at localities where geological exposures were poor. 



We reached the site of Fort Yukon on August 2, and there landed Mr. 



*S|.elled in four ways: "Bering," " Reering," " Behring," and " Bhering." The third hum has 

 the authority of the gazetteers, but the first is preferable and appears in the accompanying map, pi. 2. 



