204 The American Geologist. October, i898 
With an area nearly equal to that of New Jersey, Okan- 
ogan county may be characterized as a very mountainous re- 
gion. Proceeding from the Cascade spurs and foothills, whose 
bases the Columbia river washes, throughout the course of 
its "big bend" at an altitude of only 600 or 700 feet, the county 
rises rapidly to the west and north, culminating in an alpine 
region on the west and north-west, which abounds in glacier- 
scored peaks and bleak aiguilles ranging in hight to 10,000 
feet. The mountains being composed almost exclusively of 
crystalline rocks, the scenery is bold and rugged in the ex- 
treme. 
The drainage is effected by five principal streams which 
flow south-east or south to join the Columbia river. Of 
these perhaps the oldest in point of origin, but certainly the 
newest in its immediate surroundings is the Chelan river, 
which drains the lake of the same name. In width a river, but 
in depth exceeding any of its kind , yet measured in North 
America, lake Chelan winds for 60 miles between precipitous 
mountains, whose bases meet at least 1500 feet below. Start- 
ing from the head of the lake at an altitude of 970 feet, the 
valley is continued for 30 miles into the heart of the highest 
Alps and drained into the lake by the Stehekin river. Rising 
in a chain of lakes in British Columbia, the Okanogan river 
passes through the county with a broad valley, in a course al- 
most due south. With reference to its present conditions, it 
is to be reckoned one of the oldest streams in eastern Wash- 
ington, since with the help of a little ''lining up," it can be 
navigated to its head in Okanogan lake. It meanders along 
a valley floor which is often a mile in width, and this is greatly 
augmented in places by the flat-topped terraces, of which I 
shall speak later. Midway between these two streams lies the 
Methow river, a rapid, treacherous stream which runs for a 
hundred miles or so wholly within the limits of the county. 
.\ smaller stream, the Entiat, parallels lake Chelan, which lies 
to the eastward, in a narrow valley ; while the Wenatchee river 
bounds the county on the south-west. 
Of these rivers nothing more need be said until we come 
to the consideration of glacial phenomena. But the pre- 
glacial course of the Columbia river, which is also the present 
course, needs to be accounted for. It can be done by refer- 
