FORMATIONS OF THE VASHON EPOCH. 145 
a specific name and at the level of this bed. The material is thoroughly 
rounded. Sand, small pebbles, and larger pebbles up to 6 inches (15 
centimeters) in diameter are intimately associated, with irregular strai- 
fication and occasional cross-bedding ‘The formation is such as is now 
being formed by Carbon river, which is overloaded with coarse and fine 
detritus from the glaciers of mount Rainier. Five to 15 feet (2 to 5 
meters) above the base of the Douty gravels in the section observed 
rocks of subangular form up to 4 feet (14 meters) in diameter were ob- 
served. In association with the coarse, stratified gravel they suggest 
transportation on ice-cakes. 
The Douty gravels thus indicate a river, comparable in transporting 
power with Carbon river, flowing from a glacier and sweeping down 
loaded ice-cakes. The episode immediately antedated the Osceola till 
and may safely be correlated with an early part of the Vashon epoch. 
The formation is local and should not be identified in other drainage 
areas where the dates of similar formations, although of the same epoch, 
may nevertheless be materially earlier or later. 
PUYALLUP INTERGLACIAL EPOCH 
History of the Admiralty ice-sheet.—The term interglacial is here appled 
to an epoch of milder climate than that which permitted the accumula- 
tion of extensive glaciers in the Sound basin. The degree of mildness 
implied is relative only. An ice-sheet which will hereafter be described 
as the Admiralty ice-sheet had occupied the Sound basin. Its with- 
drawal was occasioned by the change to the milder climate of the inter- 
glacial epoch. A return of more severe climatic conditions caused the 
development of the Vashon glacier, which vanished with the gradual 
advent of the present mildness. 
The record of the inter-Admiralty-Vashon, or Puyallup, epoch may 
exist in various forms, as eroded surfaces, as subaerial deposits including 
soil and swamp accumulations, and as lacustrine or marine formations. 
The duration of the epoch may be indicated directly by the magnitude 
of the effects of erosion or deposition, or indirectly by results of oxida- 
tion and decay of Admiralty formations as compared with the condition 
in these respects of Vashon drift. 
We have as yet no knowledge of these various facts sufficient to permit 
us to draw a conclusion as to the character of the Puyallup epoch. It is 
possible that the Admiralty ice disappeared completely from the low- 
lands and even from the mountains; but as glaciers now linger in the 
Cascades, such total disappearance would indicate an interglacial climate 
warmer than the present, which is not probable. It is‘not unlikely that 
the condition of the Sound basin, as the Admiralty ice stagnated and 
