In a dark underground warren of tunnels in Alabama known as “19th Unnamed Cave,” ancient Indigenous American artists once traced figures resembling humans and animals into the mud on the cave’s walls and ceilings.

The drawings, known as glyphs, were first studied in the late 1990s. Now, thanks to state-of-the-art 3D photogrammetry techniques, researchers have been able to detect new glyphs that were previously too faint or large to be seen by the human eye within the dark and tight confines of the cave.

Anthropomorph in regalia (1.81m tall) from 19th Unnamed Cave, Alabama (photograph by S. Alvarez; illustration by J. Simek).

The glyphs were drawn over a millennium ago and are believed to be the largest cave artworks in North America. Among them are recognizably anthropomorphic figures believed to be wearing ceremonial clothes and one image resembling a diamondback rattlesnake that reaches more than 10 feet in length. Other discovered animals have included birds and insects.

The artists worked by torchlight and likely had to crouch due to the cave’s low ceilings. The exact location of the cave, a veritable treasure trove of Native American cave art covering 4,300 square feet, has been kept secret to protect the art from damage or looting.

Anthropomorph in regalia (2.08m tall) from 19th Unnamed Cave, Alabama (photograph by S. Alvarez; illustration by J. Simek).

The new images were developed using photogrammetry, a technique that uses photographs to create 3D models of a person, object, or surface. The project’s researchers took 16,000 photos of the cave over the course of two months, using them to make a highly detailed, manipulatable digital model, which has made the artworks much easier for researchers to study.

“It allows a brief glimpse into the genius of these artists,” said Stephen Alvarez, the founder of the Ancient Art Archive and the producer of an animated model of the cave available to view online (see a video below).

Anthropomorph in regalia, with a rayed circle in the midsection (0.93m tall) from 19th Unnamed Cave, Alabama (photograph by S. Alvarez; illustration by J. Simek).

The new discoveries were published today in the journal Antiquity by the team of researchers, led by archaeologist Jan F. Simek from the University of Tennessee in Knoxville, who worked alongside Alvarez and photographer and cave specialist Alan Cressler.

The researchers say we can only guess at the artworks’ meaning, but speculate that they may depict spirits of the underworld dating to the Middle Woodland period.

Serpent figure with a round head and diamond-shaped body markings from 19th Unnamed Cave, Alabama. Note that the base of the engraved glyph joins a natural fissure in the ceiling limestone (3.3m long) (photograph by S. Alvarez; illustration by J. Simek).

The discovery challenges the long-held assumption that large-scale cave art was only present in the American Southwest.

“These images are different than most of the ancient art so far observed in the American Southeast and suggest that our understanding of that art may be based on incomplete data,” Simek said.

See a video detailing the new research below.