134 B. WILLIS—DRIFT PHENOMENA OF PUGET SOUND. 
fore 70 feet (19 meters) above the margin of the delta terrace already 
defined as bounded by the contour of 1,080 feet (829 meters). It is sep- 
arated from that delta by a slightly elevated margin characterized by 
kettles and coarse gravel, which represents a temporary stage of mo- 
rainal accumulation. This morainal zone widens toward the north and 
east. Kettleholes 40 feet (12 meters) deep and 300 feet (91 meters) across 
“are numerous and frequently tangent to each other They represent ice- 
blocks, which were buried by the river deposits as the stream flowed past 
the ice-front. Beyond the zone of kettles a deep gash in the terrace front 
leads down to the valley of Gale creek, debouching near Wilkeson at an 
elevation of 820 feet (250 meters). The gash marks a temporary water 
course. 
The several deltas and stream terraces between the elevations of 1,600 
and 1,080 feet (488 and 329 meters) in the vicinity of Carbonado and 
Wilkeson record the fluctuations of the furthest advance of the Vashon 
ice-sheet southeastward. They probably form a continuous sequence in 
which the highest is the oldest; but it is barely possible that the lowest 
belongs to the series of stratified deposits formed before the Vashon ice 
advanced. The fact that it is not covered by the characteristic till of the 
Vashon episode indicates, however, that it is later and was developed 
when Carbon river had been diverted from its northeastward to its north- 
westward course. The gash in the terrace front leading down to Wilke- 
son would seem to be of even slightly later date. Ifso, it was cut by a 
short-lived stream. ‘The relations of ice-masses and rivers in the dis- 
trict between Carbonado and Buckley will yield an interesting result to 
detailed investigation. 
The several courses of Cedar river,so far as they have been traced within 
the Tacoma quadrangle, record interesting relations between the Vashon 
glacier tongues and the Cascade glacier. From a point which is 5 miles 
(8 kilometers) north of Black diamond, Cedar river has at different times 
flowed south, southwest, north, and northwest, the last being its present 
course. ‘The positions of the river were determined initially as the gla- 
ciers receding from confluence left between them a course open toward 
the southwest, and later as the further recession of the Vashon ice-mass 
uncovered lower outlets to the northwest. 
Thechannels leading southward and southeastward are swamps, known 
as the Wilderness. ‘heir elevation is about 450 feet (187 meters) above 
sea, whereas that of Cedar river at the point where it now bends north- 
ward from its older course, is 350 feet (107 meters). East of the Wilder- 
ness and lying 50 to 150 feet (13 to 88 meters) above it on strongly marked 
terraces are lakes. They are inthe moraine of the Cascade glacier, whose 
extent at this stage is also indicated by till of local character derived from 
