266 /. P. GOODE 



that such a lake not only pushes itself into the great valley over 

 sixteen miles to the southeast, but it goes on thru the nar- 

 rows at Thistle Creek, on the very level of the terrace and sea 

 cliff noted. It covers all the Hayden Valley, with the exception 

 of the very peaks of Crater Hills, and extends on past the falls 

 and the Canyon Hotel to Inspiration Point, thus making a great 

 twin lake extending over fifty-one miles from Inspiration Point 

 on the north to Hawk's Rest far down into the Absarokas on the 

 southeast. This greater lake is shown in the map by the lighter 

 shaded area. The darker shading showing the area of the pres- 

 ent lake. 



The only assumption necessary in this reconstruction, is the 

 absence of any considerable crustal deformation in postglacial 

 time, and so far as known there is no evidence of any appreciable 

 change of this kind in the area during this time. 



Let us look now at the character of the Grand Canyon as it 

 appears among its neighbors. The dominant topographic feature 

 of the northeast part of the park is the great Lamar Valley. It 

 is over two thousand feet deep, and its walls have receded under 

 the tooth of time until a broad and generous vale a mile and 

 more in width at bottom extends for twenty-five miles above 

 the point of its confluence with the Yellowstone River. This 

 vale was old in the Pliocene. It was deep and of generous size 

 before the rhyolites and basalts were poured out to mask the 

 old drainage and make the plateau in which the Yellowstone 

 Lake and Canyon now lie. Once see this great valley and the 

 impression is inevitable that the Yellowstone Canyon is a very 

 late comer. Moreover, as a canyon it is not of much more 

 importance than its neighbor of Tower Creek on the west. In 

 short, the Yellowstone Canyon, from Junction Butte back to the 

 east flank of Mt. Washburne, is not the work of the Yellow- 

 stone River at all, but was made by Broad Creek, then a small 

 tributary of the Lamar, of no more consequence than Tower 

 Creek, which joined it from the west. Its canyon may have 

 been begun in preglacial time, but long after the general ice- 

 sheet had left the region it remained an obscure stream, slowly 



