Inundated fan really. Along the lower Verde River in Arizona lie two dams. The upper dam creates Horseshoe Reservoir which is seasonally filled and drained to feed Phoenix's water needs. While out mapping in the area we took the opportunity to explore the are below the high water line while the reservoir was empty. Numerous small fans spill into the reservoir and onto what was the former river's floodplain. On one of these fans lies an interesting structure, a Hohokam era ruin. The seasonal filling of the reservoir results in a high water line of driftwood, and trash near the apex of many fans. The fan channels seem to fluctuate laterally more dramatically during low reservoir levels probably due to the constant backfilling of tributary channels, addition of lovely layers of pond much, and the ubiquitous cocklebur plants covering the reservoir bottom. Horseshoe Reservoir is an interesting place but I'd wager it was much nicer before the (damn) dam.

Reservoir empty, ruin just to the left of the crosshairs

Low walls of the ruins can be seen in the middle ground. Now covered by reservoir mud and cockleburs. The riparian trees in the background line the modern low reservoir level Verde River

Ruin wall. Otter feces were found on another portion of the ruin so at least it still gets some use