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Indiana's Prehistoric Mounds and Earthworks

Angel Mounds State Historic Site
Angel Mounds State Historic Site

The Department of Natural Resources, Division of Historic Preservation & Archaeology (DHPA) worked with several key archaeology partners in 2008 to propose an inventory of the reported and known pre-European-contact Native American mounds and earthworks sites throughout the state.

What are Earthworks

Earthworks are Native American constructions made by digging earth and piling it systematically to form mounded walls and elevated areas.

Sugar Loaf Mound
Sugar Loaf Mound


Earthen constructions showing signs of ritual activity.


Enclosures generally feature a bank and ditch construction, can be rectangular or round (often 100’ to 400’ in diameter), may feature an entrance or gateway through the bank, and may contain a mound.

Earthwork Complexes:

Earthwork complexes are groupings of enclosures and/or mounds in proximity to each other.

All of these earthwork types had ceremonial and/or mortuary functions. But these functions may have differed between feature types and in different locations.

What we learned

This inventory resulted in the documentation of 1,183 sites that contain at least 2,100 individual earthworks. This project was entirely a search of records and literature; no field work, survey, or investigation was performed. The inventory showed that virtually all of Indiana’s earthworks have been damaged by uncontrolled digging and various agricultural and construction activities. Most of the sites need additional investigations to record more precise locations and to document their current conditions since many of them have not been visited by an archaeologist in several decades. Additionally, few of the earthworks have excavation data that allow for a determination of age and cultural affiliation.

Documentation of Indiana’s earthworks began as early as the 1790s, and shows that mounds and other earthworks are found in almost every county. Several patterns in the records are apparent.

  • Almost all of the earthworks in the state were reported to archaeologists and were not discovered through systematic archaeological investigations.
  • Virtually every earthwork has been damaged, primarily through uncontrolled digging by curiosity seekers.
  • Of the earthworks that actually were visited by an archaeologist, many have not been checked in several decades, some in more than 50 years.
  • Many of the reported mounds that have been visited by an archaeologist were found to be natural features, created by glacial activity and erosion and oftentimes containing burials, rather than being man-made earthworks.
  • There is a distinct lack of recorded data from earthwork sites, from basic size measurements to details of excavations.  Further, much of the excavation data from early investigations is so generalized as to be of limited usefulness in defining horizontal and vertical stratigraphy, chronology and context for features within sites.
  • Site locations are, in general, poorly recorded and the majority of earthworks require field checking to acquire accurate locations.

Overall, these patterns reveal that earthworks within the state are very poorly documented.

Where to go from here

  • Standardization of site types - A significant challenge to the records search was the various ways in which mounds and earthworks were identified and described. Early recording of these resources leave a lot of room for errors in location, type and associated sites. Going forward, the project partners agreed that a system that standardizes these types of sites will help reduce confusion and help archaeologists better identify, document and assess mounds and earthworks.
  • Continued education/training in the archaeology community - Mounds and earthworks are a specific type of site and require a certain level of understanding and training to identify and assess. Providing continued education and training to professionals, avocationals, and even the general public will help protect the mounds and earthworks that remain.
  • Field verification of mounds and earthworks - Many of the sites identified through this project have vague location information, have not been visited by professional archaeologists, or are in rapidly developing areas. Therefore, some sites may in fact be natural features, or have been damaged and destroyed. It is important for qualified archaeologists to assess and document sites that are endangered or about which little is known.
  • Listing mounds and earthworks in the National Register of Historic Places - As field verification and investigation is undertaken, sites should be determined for eligibility to the National Register. In some cases, sites may be individually eligible, but sites that share cultural affiliations may benefit from a Multiple Property Documentation Form that would establish criteria for listing for specific kinds of mounds and earthworks.

What can you do?

Where can you learn more?

General Indiana archaeology resources:

Project Partners

Archaeologists responsible for the statewide research were from:

  • University of Notre Dame
  • Indiana University-Purdue University Fort Wayne
  • Ball State University
  • Gray & Pape, Inc.

Don Cochran and Beth McCord of Gray & Pape, Inc. compiled and presented that research in a comprehensive report, which is available for review by qualified archaeologists.

Preserve America
The Preserve America program is a federal initiative that encourages and supports community efforts to preserve and enjoy our priceless cultural and natural heritage. The goals of the program include a greater shared knowledge about the nation's past, strengthened regional identities and local pride, increased local participation in preserving the country's cultural and natural heritage assets, and support for the economic vitality of our communities.