Sioux City Academy of Science and Letters. 141 
has said of the topography of Woodbury County, Iowa. 
In winter, when snow covers the ground, the landscape 
presents the appearance of a series of gigantic snow- 
drifts, beautiful to behold. 
Topogralc diwisions.—Within Dakota County are two 
definite types of topography, the dissected upland, and 
the Missouri River flood plain. 
The dissected upland has but few nearly level areas 
left to represent the once continuous rolling prairie, and 
these are for the most part in the west and southwest 
parts of the county remote from where the upland joins 
the lowland. It is along the edge of the upland that the 
maximum intensity of relief has been developed. 
Drainage.—The drainage of the upland all ultimately 
reaches Missouri River, although but little of it flows 
directly from the upland down the escarpment toward 
the river. The main tributary of Missouri River in the 
county is Elk Creek, which flows northward in the west 
part of the county to within 2} miles of the Missouri, 
where it makes a broad sweep almost reversing its direc- 
tion and flows to the southeast, emerging on the flood 
plain near Jackson. Here it swerves to a more southerly 
course for a few miles along the border of the esearp- 
ment, finally cutting away across the flood plain and 
joining the Missouri at a point about 5 miles from the 
south border of the county. Elk Creek has several tribu- 
taries not far from its own size, notably Pigeon and 
Omaha creeks, and a very great number of minor tribu- 
taries that normally are only trickling drains, but which 
after heavy rains or during the season of melting snows 
are roaring brooks, each receiving the waters from in- 
numerable rain rivulets that have cut nearly parallel 
furrows on each side of every small valley at intervals 
of a few rods apart. Thus a complete and vigorous sys- 
tem of drainage is at work, rapidly degrading the up- 
land. 
From the highest points in the bluffs above the 
river in sec. 15, T. 29 N., R 7 E., (about 3 miles north of 
Jackson) it is seen that the drainage of the upland is 
nearly all in a direction away from the river, except that 
of a small strip immediately along the escarpment, 
which has been cut into by numerous short, steep-sided 
ravines whose profiles would in many instances show a 
