848 G. K. Gilbert— Outlet of Lake Bonneville, 
lowed the: retreating shore until, at the Provo stage of Lake 
Bonneville—the lowest stage of outflow,—the point of outlet 
was at the edge of what is called Round Valley Marsh (y), nine 
miles south of Red Rock. When the lake dried away, the 
divide was left at that place, but Marsh Creek has resumed 
control of it by constructing an alluvial cone in the old river 
bed at Hunt’s Butte (a) and building it higher than the level of 
the last discharge. 
e Bonneville water line, so far as it survives, is represented 
by the heavy lines B, B. Its restored continuation and the 
restored banks of the outflowing river are represented 
by heavy broken lines. The margins of the water at its 
lowest, or Provo stage, when the point of outlet was at y, is 
shown by lighter broken lines. 
i arsh Creek was building its ancient alluvial cone, it 
ran in turn overall parts of it. Attimes it passed south of the 
divide and flowed to the Great Basin. At other times it passed 
north of the divide and flowed to the Portneuf river. When 
the outflow of the lake was initiated and the water level began 
to be lowered by the deepening of the channel of outflow it 
chanced that the creek was running over the southern part of 
its cone, and discharging into the lake at Hunt's Butte. The 
lowering of its point of discharge caused the creek to cut away 
absolutely ignorant of your examination in 1876 and its re 
sults..: ..I was very much interested in the general 
subject of its limits and also of its outlet... . Toward 
