From Marshalltown, IA, take County E29 west to County S75 and Iowa 330 junction. Continue on County E29 for 0.5 miles north and 2 miles west. Then take a gravel road north 1.25 miles to the preserve on the east side of road. Marietta Sand Prairie is located on an upland deposit of windblown sand.
Plant communities range from dry upland prairie to wet prairie and wet woodland.
Upland prairie species include sand reedgrass, sand lovegrass, big and little bluestem. Sedges and sensitive fern dominated open wet areas. Red elm, box elder, and aspen dominate the wooded area. Nearby Minerva Creek and the broad valley of the Iowa River seen to the northeast were sources of the sand that was blown here during the dry post-glacial intervals between 4,000 and 6,000 years ago. Facilities for this preserve include a parking lot and an interpretive trail.