The Obsidian Aucilla

Stained black by the surrounding swamps, the Aucilla River is an obsidian mirror; it reflects the overhanging forest while hiding a labyrinth of rocks, snags. In places it disappears, running underground – in others, it conceals deep sinkholes formed by collapsed limestone caverns. For decades, river divers have descended into these dark pits in search of extinct animals and the tools ancient humans used to hunt them. Little is clear about these ancient hunters and the Pleistocene landscape they inhabited. Over the past four years, the Aucilla River Geoarchaeological Expedition has been conducting extensive coring, land and underwater excavation to understand the role that sinkholes once played for these people.

Divers at the Surface - 2010 © Jessi Halligan

Fifteen thousand years ago Florida was drastically different. Water levels were lower; there was no Aucilla river, just a series of watering holes in a periodically dry forest.  These freshwater pools were prime hunting grounds for Florida’s first peoples. They ambushed and butchered the mastodons and mammoths that came to drink at the sinks. In time, silts buried the remains, preserving the bones as the world changed. Swamps and tropical forests emerged, the Gulf drew closer and a new river cut a path from waterhole to waterhole, eventually becoming the Aucilla in its current form.

The Aucilla River, early morning - 2011 © Douglas Inglis

Bone from the 2010 excavation - 2010 © Jessi Halligan

Today, this shallow waterway winds through Florida’s Big Bend. It has sinkholes that drop as many as twenty meters below the surface and are up to two hundred meters long. Since the 1970’s, divers have been working with archaeologists and paleontologists to explore and document the river’s ancient deposits. The waterway has produced several fully articulated mammoth and mastodon skeletons and more ivory artifacts than the rest of North America combined. Clovis points are common, and the Aucilla holds artifacts that are potentially much older.

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Categories: Aucilla River, Prehistoric Archaeology, SCUBA

Author:Doug Inglis:

I study the archaeology of seaborne exploration and contact. I am passionate about public history and outreach, and write about nautical archaeology at

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