The mounds range from 6 inches to 4 feet in height and from 12 to 40 feet in diameter. The site provides an excellent view of one of Iowa's best known examples of stream capture. The Little Maquoketa River formerly flowed south, through the Couler Valley at the foot of the ridge. Glacial meltwater flooding the Mississippi Valley broke through the narrow divide which separated the drainages. It diverted the Little Maquoketa directly east into the Mississippi.
Vegetation is typical of that found along bluffs of the Mississippi River.
Dense second-growth hardwood forest of oak and hickory predominates. Facilities at the site include a designated parking area , an established trail and an interpretive display. See the Introduction for general use of state preserves. 13768 Swiss Valley Rd.