Reimagining the Development of Downtown Cahokia Using Remote Sensing Visualizations from the Western Edge of the Grand Plaza

Abstract

The distribution of mounds, plazas, and defensive palisades associated with Cahokia Mounds State Historic Site (CMSHS) defines the core urban environment of Eastern North America’s first American Indian city. The large mounds surrounding Cahokia’s centrally located Grand Plaza, including the palisades that enclose them, are referred to as Downtown Cahokia. In this portion of the site, archaeologists have identified material culture (e.g., ceramics), earthen fills to level the plaza, and several earthen mound constructions. These findings suggest an occupational history for the area that occurred over the 9th–14th centuries CE, with the emergence of plaza delineation and earthwork construction beginning in the early 11th century CE. In sum, Downtown Cahokia and its Grand Plaza are considered by archaeologists to be a vibrant space characterized by ongoing American Indian transformations to an early metropolitan landscape. We conducted magnetometer and electromagnetic induction surveys at the western edge of the Grand Plaza. When compared with the LiDAR-derived visualizations we generated from this portion of the site, our aerial and terrestrial remote sensing data offered new information on the nature and sequence of monument construction in Downtown Cahokia, as well as architectural changes in domestic and special-use structures. These multi-scalar and complementary remote sensing datasets allowed us, without excavating, to trace important sequences of change in Downtown Cahokia’s history.

Keywords

• Cahokia Mounds
• USA
• landscape archaeology
• historic aerial photographs
• LiDAR
• magnetic gradiometry