Turkey River Mounds State Preserve

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State Preserves

Turkey River Mounds State Preserve is a 62-acre area containing a large complex of ancient Indian mounds on a spectacular narrow ridge overlooking the confluence of the Turkey River and the Mississippi River. It is located 4.5 miles southeast of Guttenberg in Clayton County.

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About the Land

The first exploratory survey of the mounds was conducted in 1885. The site was revisited by famous Iowa archaeologist Ellison Orr in the early 1930s. The property was purchased by Dubuque citizens in 1934 and given to the Iowa Conservation Commission in 1940. Later archaeological surveys were conducted in 1964 and 1973. 

The area was dedicated as an archaeological, geological, and biological state preserve in 1968. It was also placed on the National Register of Historic Places in 1990. 

Geography

Located in the Paleozoic Plateau landform region, the preserve is situated on a narrow ridge with precipitous bluffs rising 250 feet above the Mississippi floodplain. 

The bluffs are composed of resistant Galena Group dolomite of Ordovician age (450 million years old) that has weathered into picturesque pinnacles. 

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Directions

  1. From Guttenberg, take Highway 52 south 5.5 miles to Estes Point Road. 
  2. Turn east (left) and go 2 miles to the parking lot for the preserve (sign: Turkey River Mounds State Preserve).
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Ceremonial Mounds

The summit of the ridge consists of forty-three conical, linear, compound, and effigy mounds, thirty-eight of which are in the preserve. 

The mounds vary in size and are between 1.3 feet and 6 feet high. The conical mounds vary from 20 feet to over 100 feet in diameter, and the linear mounds range from 80 to 175 feet in length. The single effigy mound is in the shape of a panther and is 98 feet long and 40 feet wide. 

History

The mounds were built throughout the Woodland period between 500 b.c. and a.d. 900 and served as burial sites and ceremonial places. They are believed to have been constructed by basket loads of soil placed either on the ground or on a specially prepared surface. On occasion, additional burials were later added to a mound, increasing the size of the earthen feature. 

Excavated material indicates that these people traded, directly or indirectly, with people as far away as North Dakota, Ohio, and the Gulf coast. The site is important for studies of early Upper Mississippi valley burial groups as well as the Archaic to Woodland transition. 

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Plants

Several interesting plant communities can be found on the ridge, cliffs, and steep lower slopes of the preserve. 

The ridge is semiforested with white oak, red oak, aspen, paper birch, and eastern red cedar. In openings near the cliff edges, prairie plants found include:

  • Hoary puccoon
  • Little bluestem
  • Palespiked lobelia
  • Rough blazing star
  • Gray-headed coneflower

Slender lip fern and smooth cliff-brake fern plus orange and brown lichens cover much of the dolomite outcrops. 

Forests developed on the steep slopes beneath the sheer bluffs contain a variety of plants. The dry south-facing slope is dominated by:

  • White oak
  • Shagbark
  • Basswood
  • Chinkapin oak
  • Eastern red cedar

The mesic north-facing slopes are dominated by sugar maple and basswood. Wildflowers and ferns found here include:

  • Dutchman’s breeches
  • Nodding trillium
  • Bishop’s cap
  • Jeweled shooting star
  • Wild ginger
  • Bulblet bladder fern
  • Walking fern
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Visitor Information

Burial mounds are protected by law. 

An American flag was erected at the southeast end of the ridge in 1972 by the American Veterans Post 15 in Guttenberg. 

Other archaeological sites in Iowa include:

  • Effigy Mounds National Monument and Slinde Mounds
  • Fish Farm Mounds
  • Toolesboro Mounds
  • Malchow Mounds
  • Little Maquo­keta River Mounds
  • Wittrock Indian Village State Preserves
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