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
Go check this area out. Very interesting geology abounds, as always, in western China.
This complicated conflation of channels and channel patterns near the confluence of the Urmi and Amur Rivers in the Jewish Autonomous Region of Russia is mesmerizing. Seriously, go check it out. http://www.flashearth.com/?lat=48.611358&lon=134.983387&z=11.4&r=0&src=msa
The cross-hair in the Flash Earth image below is just behind home plate at the city's baseball field. Note the backstop...the Willow Creek Dam. Sure, it is pretty much the backdrop for the whole town, but the proximity to the ball field is just...so...close.
Including this particulary pathological, almost cubist, palimpsest scene:
Inspired by Brian's theme for the month, this basin and range landscape in central Idaho caught my eye. I love the way the center-pivot irrigation boundaries outline the edges of the alluvial fans. Closer examination reveals even more juxtaposition, as a river cuts through the middle of the valley, further limiting the extent of agricultural and human influence. I'd imagine that the arable areas have been somewhat dynamic of historical time as the river changes course and as the fans continue to build. In the second image, you can see some incomplete irrigated circles, where presumably the alluvial fan is too active to allow agricultural productivity.
The flash earth imagery is also rather nice. http://www.flashearth.com/?lat=44.553052&lon=-113.819471&z=11.9&r=319&src=msa