Slinde Mounds State Preserve

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State Preserves

Slinde Mounds is a 32-acre preserve containing a group of ancient Indian mounds and a hill prairie along the Upper Iowa River. It is located six miles northwest of Waukon in Allamakee County. 

First discovered in 1934 on the Slinde family property by archaeologist Ellison Orr, the site was purchased by the Iowa Conservation Commission in 1979 and dedicated that year as an archaeological and biological state preserve. 

In 1989, the preserve was listed on the National Register of Historic Places. 

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About the Land

Located in the Paleozoic Plateau landform region, the preserve is situated on a high terrace and adjoining hillside that overlooks a tight horseshoe bend of the Upper Iowa River. 

The meander loops around a prominent rock outcropping of Ordovician-age Prairie du Chien dolomite (450 million years old) that marks the level of an ancient floodplain. When the river later eroded more deeply to its present level (about 70 feet lower), this remnant was left behind. 

Burial Mounds

The preserve contains three prehistoric sites dating from a.d. 300 to 1250 during the periods of Middle and Late Woodland Indian cultures. The eighteen conical burial mounds and two habitation sites in this preserve are representative of the prehistoric culture found in the Quad-State Region of the Upper Mississippi River valley. 

Earthen mounds such as the ones found at the preserve were primarily constructed for burial of the dead, as well as for the performance of ritual offerings and ceremonies. Conical-shaped mounds were built by basket loads of soil placed on the ground. On occasion, additional burials were later added to a mound, increasing its size. 

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Directions

Access to this preserve is across private land.

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Plants

The preserve is covered by native prairie and forest vegetation. 

Native Prairie

The dry hill prairie is dominated by little bluestem and sideoats grama with a variety of prairie wildflowers. 

As early as March, pasqueflower can be found blooming, followed later by: 

  • Bastard toadflax
  • Hoary puccoon
  • Pussytoes
  • Prairie violet 

By June, indigo bush, blue-eyed grass, leadplant, prairie coreopsis, and prairie rose are blooming, later joined by compass plant and silky aster. 

Forest

The mature forest area is dominated by white oak, bur oak, and shagbark hickory. 

In the spring, spring beauty is an early bloomer and can be seen as early as March. 

By mid-April, blooms include:

  • Dutchman’s breeches
  • Wild ginger
  • Downy yellow violet
  • Jack-in-the-pulpit
  • Wild geranium
  • Alum root
  • Swamp buttercup
  • Violet wood sorrel

 They will last through mid May or early June.

 By the summer months small-flowered buttercup, Virginia waterleaf, false Solomon’s seal, leafcup, and jewelweed appear. 

They can be found among the leaves of: 

  • Northern maidenhair fern
  • Smooth cliff-brake fern
  • Northern lady fern
  • Spinulose wood fern
  • Interrupted fern 
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Visitor Information

Hunting is permitted. 

Burial mounds are protected by law. 

Other state preserves in Iowa with archaeological mounds include: 

  • Catfish Creek
  • Fish Farm Mounds
  • Little Maquoketa River Mounds
  • Malchow Mounds
  • Toolesboro Mounds
  • Turkey River Mounds
  • Woodland Mounds
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