Drift near Sarttle, Tacoiiia and Olyiiipia. — I'pluiin. 209 
soutli, side of Cedar river has these shales at its base, eroded 
to ail undnlatinp^ contour, on which till was deposited to the 
thickness of 5 to 15 feet, succeeded by 75 feet of sand and 
gravel, containing" cobbles up to 6 or 8 inches in diameter. 
Stewart street in Seattle, at its summit level, about 175 
feet alx)ve the sound, in front of the Hotel Washington, has 
cut through the thin drift, which there is coarse gravel, into 
the shales, which contain in that place a layer of lignite, 4 to 6 
feet thick, in part clayey, about 10 to 15 feet beneath the orig- 
inal surface, horizontal but here and there considerably con- 
torted as if by the pressure of the overriding ice lobe. The 
lignite is seen along an extent of fully 250 feet at the upper 
north side of the street excavation, and also for a less extent 
on its south side, wdiere this layer outcropped on the natural 
surface. 
In Tacoma, twenty-five miles south of Seattle, till generally 
forms the surface, which ascends in moderately steep slopes 
to a bight of 350 feet; but street grading or other and deeper 
excavations often pass through the till, penetrating into an 
extensive mass of modified drift, irregularly bedded gravel and 
sand, probably a subglacial deposit. A notable cnaracteristic of 
the till here is that many of its small rock fragments, about 
three fourths of all in some excavations, are well rounded peb- 
bles and cobbles, up to 8 inches in diameter, derived from pre- 
glacial valley gravels. Otherwise the till is quite typical, very 
hard and compact, with only a moderate supply of stones 
and few boulders, yet having some l)oulders 2 to 3 feet in 
diameter or larger. 
Till and thick undcrlxing modified drift continue five miles 
northwest from Tacoma to i'oint Defiance, where they are well 
exposed in freshly undermined sea cliffs. Throughout the 
neighborhood of Seattle and most of the city area of Tacoma, 
the drift surface is smooth, without the knolls and small ridges 
peculiar to marginal moraine tracts ; but in I'oint Defiance 
park, and thence southward eight miles to Chambers creek, 
it consists of knolly and ridgy till, with more than the ordinary 
proportion of boulders, possessing thus well marked morainic 
characters. The knolls, however, as seen on the railways going 
to the park and to l^teilacoom. are seldom more than 10 to 
