114 B. WILLIS—DRIFT PHENOMENA OF PUGET SOUND. 
elevated plains or plateaus and (2) hollows long, narrow, and deep. 
The relations of these two classes are simple: The hollows surround the 
plateaus which are thus islands, except on the extreme eastern and 
western sides of the basin where the plateaus form elevated benches 
along the foothills of the adjacent mountains. To enumerate types there 
are of islands: Whidbey island, the Great peninsula, Vashon island, and 
Des Moines island ; and of hollows: Hood canal, Admiralty inlet, Du- 
wamish valley, and Puyallup valley. The minor features of the region 
are of three genetic classes, namely, (a) features due to constructive ice- 
work, (b) features due to constructive water work, and (c) features due 
to destructive water work. In the following table the several types are 
specified. 
a. b. G 
Features due to constructive 
ice work generally aided Features due to construct- | Features due to destruct- 
by water. ive water work. ive water work. 
Undulating till plains........ Gravel plains........... Stream terraces. 
Osars and kames............. Delta terraces........:.. Ravines. 
Moraiives saan coms cone oe Alluvial cones........... Cutbanks. 
amie vernalcesaaeer ene ere Alluvial plains......... | Sea-cliffs. 
Walkesbaisinisspiciers sears ole ngs) CKESU oa eceeo oactat cents Wave-cut terraces. 
A common topographic feature which does not come under any of the 
above types is the landslip, scarp, and terrace, which frequently simu- 
lates, modifies, or destroys other topographic individuals. 
DESCRIPTION OF THE MAJOR TOPOGRAPHIC FrATURES 
PHYSICAL CHARACTERS IN GENERAL 
Within the region of Puget sound the topographic forms of greater 
magnitude are determined by masses of stratified and unstratified drift, 
whicheonstitute the islands. Water and alluvium occupy the interspaces 
or hollows. Outerops of the underlying rocks of Cretaceous and suc- 
ceeding periods are rarely visible. The minor topographic features are 
carved in the drift masses or modelled on their surfaces. ‘To the north 
and northwest the San Juan islands and Vancouver represent a height- 
of-land in which hard rocks more generally rise above the drift. 
PLATEAUS, THEIR DISTRIBUTION AND CHARACTER 
The major elevations of the Puget Sound basin are of the plateau type. 
They are essentially flat topped and are bounded by steep slopes descend- 
