Atwater was recognized by contemporaries as a pioneer of the study of the mounds or massive earthworks in the Ohio Valley; he published an account during 1820.

[1] At the time, Atwater and other scholars developed various theories of origin; he thought a culture other than ancestors of Native Americans created such monuments.

He helped publicize a theory by John D. Clifford, an amateur of Lexington, Kentucky, who suggested that people related to Hindus of India had migrated by sea and built the mounds, to be replaced by ancestors of contemporary Native Americans.

Atwater practiced law for six years, and gained an assured income when appointed as United States postmaster of the town.

During the late 1830s, people decided they wanted an ordinary town with a grid pattern, and the remnants of the circular works were destroyed.

Elected to the state’s house of representatives during 1821, Atwater endorsed internal improvements, including legislation that authorized the Ohio and Erie Canal.

An enthusiastic Jacksonian Democrat, Atwater was appointed by President Andrew Jackson during 1829 as one of three federal commissioners to negotiate the Third Treaty of Prairie du Chien with the Ho-Chunk in Wisconsin.

His journey to Wisconsin and meeting with Native Americans stimulated him to write about his experiences in the west: Remarks Made on a Tour to Prairie du Chien (1831), which includes an interview with the noted Sauk leader Quashquame.

Atwater is known as one of the first researchers to undertake a serious study of the prehistoric Adena and Hopewell culture earthworks, and their associated artisan artifacts found throughout the Ohio Valley.

This account, considered the first scientific treatment of the monuments, is illustrated with woodcuts of artifacts and with engraved maps of prehistoric sites.

[4] Clifford published "Indian Antiquities,” eight long letters in Lexington’s short-lived Western Review and Miscellaneous Magazine (1819-1820), with material from Rafinesque.

[4] He proposed a theory, circulated more widely by Atwater, that the mounds were the work of ancient people related to the Hindus of India, who had reached North America by sea.