210 The American Geologist. October, 1904. 
20 feet high; nor does the drift accumulation seem much great- 
er than on the smooth areas. 
Southward from Chambers creek, as about Steilacoom and 
American lakes, and at Parkland and southward on the railway 
from Tacoma to Spanaway lake, the surface is stratified gravel 
and sand, in far reaching plains, extending to the drift boun- 
dary. These Steilacoom plains, as they are named by Willis, 
are 250 to 350 feet above the sea. Spanaway laice, one mile 
long, at the hight of 329 feet, is of the same type as many 
others inclosed thus by modified drift, being probably the site 
of a finally isolated remnant of the melting ice border, which 
was surrounded by the rapidly deposited gravel and sand. 
When the ice mass melted, it left a hollow and lake. 
Frt)m Steilacoom, Parkland, and Spanaway lake, only strati- 
fied drift gravel and sand were seen along the distance of 
about twenty-five miles southwest to Olympia and twenty 
miles onward to Gate, at the edge of the drift. In all 
that distance, nearly fifty miles, only two or three boulders 
were seen, these being 3 or 4 feet in diameter, in the 
fine sand of the modified drift about two miles southwest of 
Olympia, on the ascent to the watershed near Black lake. The 
deposition of the sand and gravel took place evidently close 
outside the retreating ice margin at the end of the Glacial 
period. 
About a quarter of a mile southwest of Olympia depot, on 
the south side of the railway and near the end of this arm 
of the sound, is a well exposed section 60 to 100 teet high, con- 
sisting of very fine sand and clay beds, all laminated, with no 
gravel, dipping 2^ to 5" eastward. These beds, rarely exposed, 
form: the lower half of the plateau country adjoining the end 
of the sound; but the upper half, rising to 200 or 250 feet, is 
sand and gravel, irregularly bedded, often very coarse, with 
cobbles up to 5 or 6 inches in diameter. 
One of the many excavations in this modified drift of Olym- 
pia has a part that resembles till. It is a half mile east from 
the center of the town, and at the estimated hight of 150 to 
160 feet, being a dark gray, very compact and very coarse 
gravel, with abundant stones up to 8 inches, all somewhat 
watervvorn, — thus containing too many cobbles to be regarded 
as till, and having no boulders. That deposit, 10 to 15 feet 
