104 
IOWA ACADEMY OF SCIENCE 
This valley and the territory enclosed by this stream received most 
attention in the work. All bnt a few species found elsewhere in the 
county were duplicated within its drainage system. On account of! its 
meandering course its current is slow and its bottom latnds are rich in 
alluvium. All along its course, it offers many bogs and swales, or 
low rich ground so favorable to sedges. 
Crooked Creek drains the country around Winfield, and numerous 
other small streams all pay tribute to the Skunk River system. 
Two distinct topographical areas are recognized in the county. The 
first consists of an undulating prairie, moderately well drained 1 and 
occupying the north and northeastern portion of the county. This re- 
gion belongs mostly to the Kansan drift plain, but it is not well eroded, 
due to its distance from any stream of considerable size. Rounded 
ridges of irregular hills mark the marginal moraine of the Illinoisan 
drift sheet in the eastern part of the county. These hills extend north- 
ward from Baltimore to' New London townships and 1 may be seen from 
Canaan. They pass out of the county in a northeasternly direction. 
Further south, in Baltimore township, they are crossed by the Skunk' 
River and lost in the eroded surface. 
The second distinct topographical area is represented by the southern 
and western portion of the county and is well eroded. The topography 
here has been impressed upon it largely by the Skunk River and its 
dendritic branches. These streams have intersected the region in all 
directions, cutting their channels entirely through the drift into the 
underlying rock. This gives us here a very rugged country, a diversified 
landscape of hills, upland, and valley. 
The central portion of the county lies between these two topographical 
areas and combines the characters of both. Beginning a few miles north 
of Mt. Pleasant, as one goes south, the topography of these two areas 
gradually blends from the prairie upland type to the rugged hills and 
bluffs of the Skunk River. Thus it is possible that this area which 
was most extensively studied is quite representative of the whole county 
in its floral conditions. 
Big Creek and its valley, the Skunk River south of Mt. Pleasant, and 
the intervening prairies receive considerable attention. This area af- 
fords a variety of conditions. The prairies north offer many bogs and 
swales; the low bottom lands of the # Skunk River and Big Creek with 
their timber, offer swamps and marshes in alluvial soil, and the forested 
hillsides and open prairies bordering these streams, offer a great variety 
of conditions, all within a rather small area. 
