EVERGLADES NATIONAL PARK, Fla. (AP) — Archaeologists are poking through the muck under a boardwalk in Everglades National Park, looking for evidence of a prehistoric culture in an especially challenging search environment.

Work began Friday along a 0.8-mile trail around a shallow pond amid sawgrass. National Park Service archaeologists this week are sampling sediment down about 10 feet to the bedrock every 5 meters along the boardwalk, sucking up mud and water with an aluminum tube and then dumping the contents over a screen.