Archaeologists Dig Up 1,400-Year-Old Native American Canal in Alabama

In the beachside resort town of Gulf Shores, Alabama, locals had often referred to an odd feature in the landscape as “Indian ditch.” As far back as the 1820s, a handful of antiquarians and United States Army engineers recognized it as a feature that predated white settlers, but it hadn’t received enough scholarly attention to explain its history and function. One resident, Harry King, who had been exploring the back bays of the region, became fascinated with the remnants of this large trench, about 30 feet wide and 3 feet deep. On visits to the archaeology museum at the University of South Alabama in Mobile, King would encourage researchers to examine it. Gregory Waselkov, a now-retired anthropologist at the university, figured the ditch was probably an antebellum construction built by enslaved laborers.

“It took me forever to go out there and take a look,” says Waselkov. “There are lots of features like that in the swampy areas around Mobile, from logging, and from rice cultivation—there are all kinds of reasons you might have big ditches. But when I saw it, I realized it’s something different.”

Thanks to King’s urging, Waselkov finally began an investigation of the site in 2017 with a team of volunteer archaeologists. They confirmed that this long-overlooked trench is a feat of engineering and a rare archaeological find: a canal, nearly a mile long, built for canoe travel 1,400 years ago by the Native Americans who navigated the region’s waterways. In a report published online in June in the Journal of Field Archaeology, the researchers described how the canal would have connected the Gulf of Mexico with more protected bays, allowing better access between coastal fishing areas and trade routes to the rest of the Southeast.

“I think one of the things that [this discovery] underscores is the incredibly engineered landscape that exists among the Native peoples of the Gulf Coast,” says Victor Thompson, director of the Laboratory of Archaeology at the University of Georgia, who was not involved in the study but reviewed it.

“They were able to engineer these landscapes that allowed them to flourish for millennia,” he adds. “The archaeology is so fantastic in this region, it has such an interesting history, and it speaks to the sophistication and ingenuity of Indigenous societies in the Southeast who have contemporary descendant communities."

Though much of the canal has been lost to development today, in its heyday it would have stretched a little less than a mile across most of Fort Morgan Peninsula, from Oyster Bay in the north to Little Lagoon in the south. Both bodies of water are at sea level, but the land between reaches up to six feet in elevation. That means anyone digging a trench across the peninsula would risk draining the water table into those sea-level outlets. The solution in this case may have been two dams at either end of the passageway that canoe travelers would have had to carry their boats around. With a shallow draft, dugout canoes would have only needed a few inches of water to pass through the three-foot-deep canal. The researchers also think the canal was only navigable in the winter, when seasonal factors typically create wetter conditions and a higher water table. But when the canal was dry, it still would have made a good footpath through a heavily forested area, Waselkov says.

The team dug two cross sections of the canal. Through radiocarbon dating, they were able to place the construction between 576 and 650 C.E., at the end of the Middle Woodland period. Archaeologists of the Southeast have used the term Woodland period to describe a cultural phase in which pottery came into widespread use and societies were organized in small hamlets that sometimes built mounds.

Evidence shows a small Middle Woodland village, Plash Island, stood about 1.5 miles north of one end of the canal and was likely responsible for the waterway’s construction. Rather than circumnavigating the 19-mile peninsula through high surf, individuals from this village could have taken the canal to get to camps closer to the Gulf, where they processed, smoked, and dried fish and shellfish for better preservation. The Native Americans living in this area at the time did not use agriculture, so access to subsistence resources like fish and foraged plants was crucial.

“Traffic would have been aided immensely by this canal,” Waselkov says. “If you canoe out of Mobile Bay, out into the Gulf, I think you’d be taking your life in your hands. I would not want to do that in a dugout canoe because the Gulf is very, very wild.” (He notes, however, that evidence exists for daring canoe journeys in this region; the Seminoles and other Native American groups in South Florida crossed to the Bahamas, for example.)

The Middle Woodland period is also famous for long-distance traffic. Stones, shells and other goods were traded throughout the eastern half of North America. And this canal would have been a useful shortcut for travel between the Florida coast, Mobile Bay and beyond.

“If you’re bringing trade goods from the eastern shore of the Gulf, from the west coast of Florida, this canal is basically the front door to the Southeast,” says William Marquardt, curator emeritus at the Florida Museum of Natural History, who was not involved in the study. “Once you get into Mobile Bay, then you’d have choices to go to multiple pathways into the Southeast.”

Though archaeologists know that what was essentially a highway system of natural waterways and footpaths stretched across the Southeast, not many Indigenous canals are known in the region. At Pine Island, in southwest Florida, a 2.5-mile canal was built for canoe travel perhaps as many as 1,000 years ago by the Calusa, who established a kingdom fueled by fisheries that resisted Spanish colonization. At Mound Key, the Calusa built a shorter sea-level canal, along with “watercourts” for trapping fish. These canals are much different from irrigation canals built by Indigenous people of the Americas, such as the ones the Hokoham culture built in Arizona and northern Mexico.

“The thing they all have in common is they required knowledge of hydro-engineering and large-scale labor,” Thompson says. What makes the canal in Alabama especially unusual is its age. “It’s emerging prior to all these large polities [or organized states] that we see popping up later on. To me, it speaks to a more collective sort of labor project, rather than one that is driven top-down.”

Scholars previously assumed a culture would need strong hierarchies to harness the type of labor needed for large-scale engineering projects. The earliest evidence of stratified chiefdoms in this part of the Southeast dates to around 1000 C.E., with the beginning of the Mississippian period. Researchers typically look for disparities in graves and housing to find evidence of social hierarchies. Waselkov says little archaeological work has been done on Woodland sites of the Mobile area, but of the known remains, there doesn’t appear to be a “chiefly elite” that would have directed big construction projects.

"People assumed that there was a connection between stratified societies and canal-building because it takes a lot of cooperation to build these things, and then to maintain them,” Waselkov says. “Somebody has to keep cleaning them out for them to continue to work. And with irrigation canals, you have to divvy up the water, which creates all kinds of social conflicts. To have one … in a society [that] looks pretty egalitarian is kind of unusual.”

More recently, some archaeologists have been coming around to the idea that a rigidly hierarchical, agrarian society was not a prerequisite for complexity or even city-building. Marquardt points out that hierarchies would not have precluded the type of long-distance trade of shell artifacts, beads and other goods that Native Americans engaged in 1,400 years ago in the Eastern U.S. “We see trade and commerce today as something that makes people rich or aggrandized in some fashion, but that might not necessarily have been the case in the past,” he says. “Maybe it had a different kind of value—a ritual value or ceremonial value. Whatever it was, it was considered attractive and good to have these things and to move them from place to place.”

Marquardt praises the report’s in-depth look at the hydrological factors that would have made the canal functional. He hopes that the findings prompt other archaeologists to take a closer look at similar features in the Southeast.

“There’s more out there to be found, but they have to be looked for,” he says. “An old axiom in archaeology is that archaeologists often find what they look for—but only what they look for.”

Megan Gannon | | READ MORE

Megan Gannon is a science journalist who often writes about archaeology and space. She was previously a news editor at Live Science and Space.com.