Plum Bayou Mounds
Plum Bayou Culture Mounds · Toltec Outlier Group
Late Woodland Plum Bayou 650–1050 CE (Baytown-Coles Creek to Mississippian transition)·Plum Bayou (Baytown/Coles Creek, Late Woodland Arkansas)·🇺🇸 Arkansas, Lonoke County, United States
About
About Plum Bayou Mounds
Premier Late Woodland platform mound center: 18 mounds (tallest Mound A 12 m) enclosing 16 ha plaza with embankment ditch and astronomical causeway aligned to 1-degree solar solstice. Plum Bayou culture type-site demonstrating pre-Mississippian platform mound tradition without maize intensification. State park with museum.
Why it mattersLargest and best-preserved Late Woodland platform mound center in Arkansas, bridging Woodland and Mississippian architectural traditions.
Open questions
Mysteries & theories
Mysteries
- 01Why Plum Bayou built Mississippian-like platform without Mississippian shell-tempered pottery
- 02How causeway solar alignment was surveyed to ~1 degree
Theories
- 01Plum Bayou as Coles Creek-derived chiefdom controlling Arkansas River trade
- 02Abandonment c.950 due to environmental desiccation before Cahokia rise
Theories are interpretations, not findings. The seal above tells you how much scholarly weight the place carries.
History
How it came to be
- Built
- c.700–950 CE (Plum Bayou culture)
- Period
- Late Woodland Plum Bayou 650–1050 CE (Baytown-Coles Creek to Mississippian transition)
- Culture
- Plum Bayou (Baytown/Coles Creek, Late Woodland Arkansas)
- Builders
- Plum Bayou
- Purpose
- 18 platform mounds around plaza with 1.6 km embankment and causeway, regional political-religious center controlling Arkansas River bottomlands
- Excavation
- Partially excavated
c.700–950 CE (Plum Bayou culture)
Initial construction
1050 CE (Baytown-Coles Creek to Mississippian transition)
Major occupation / refurbishment
On the ground
Structures & features
34.6457° N · 92.0650° W · 76 m · 2 mapped features
Mound A — principal platform
platform mound12 m flat-topped platform on plaza west, tallest at site
34.6460° N · 92.0660° WCauseway and embankment
causewayEmbankment ditch and 1.6 km causeway aligned to solstice
34.6450° N · 92.0640° W