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The complex of prehistoric mound structures found at Marietta stimulated international interest even before the arrival of civilian settlers. Maps and descriptions produced by Captain Jonathan Hart, stationed at Fort Harmar, and others took news of the impressive and mysterious constructions in the American wilderness to places like Yale College in Connecticut, Thomas Jefferson's library in Virginia, and across the Atlantic to Europe.
These massive sites are now known to have been created by Native American groups archaeologists term the Hopewell Culture, operating from approximately 50 BC to AD 400. But at the time of pioneer settlement, there was much speculation about a "lost civilization" or other non-Native American groups that might have produced these impressive works.
Consisting of two large rectangular walled enclosures, long parallel walls connecting to the Muskingum River, a large circular element ("Conus" in Mound Cemetery), and various additional smaller mounds and walls, not only was the Marietta earthworks one of the first U.S. archaeological sites to stimulate widespread interest, but also a site that exhibits some unique characteristics.
Several dozen Hopewell earthwork complexes with combinations of geometric outlines extend across southern Ohio, but none have the linear arrangement of two rectangles and a circle found at Marietta. And one of those rectangles is special. Rectangular enclosures at Hopewell earthworks are typically 25-27 acres in extent (as is Marietta's smaller rectangle), but the large rectangle at Marietta was 45-50 acres - the largest ever created by Hopewell people. The basal outline of the Great Pyramid of Egypt would fit inside this enclosure four times!
Within the large rectangular area three unusual mounds were erected, flat-topped platform mounds with straight sides and ramps from ground level to their upper surfaces. Two of these still exist today, known by the names "Capitolium" (on Fifth Street with the county library on top) and "Quadranaou" (in Camp Tupper park between Third and Fourth streets). Only a handful of Hopewell earthworks include platform mounds, and Marietta is the only place where three exist together. Why this happened at the Marietta site continues to be pondered by archaeologists.
The Marietta earthworks also evidences construction and use that may cross cultural boundaries. The large conical mound in Mound Cemetery ("Conus"), along with its surrounding ditch and circular wall, is typical of the Adena Culture that preceded Hopewell. Archaeologists assign Adena to a period circa 800 BC to AD 100. Marietta is one of the best places to observe a large Adena mound directly incorporated into a larger Hopewell earthwork complex, suggesting a continuity in social and religious practices among these Native American groups.
The prominence of the Marietta earthworks in the early history of American archaeology is reflected in the first publication by the nation's natural and history museum, the Smithsonian Institution. The first volume of "Smithsonian Contributions to Knowledge," published in 1848, was titled "Ancient Monuments of the Mississippi Valley," providing a detailed record of known mound sites in that region. The first engraved illustration on the first page of that book was a view of the earthworks at Marietta.
Wesley Clarke is a member of the Washington County Historical Society and a registered professional archaeologist. To learn more about the Washington County Historical Society services and membership call 740-373-1788 or visit wchshistory.org.