Every winter I am the creek's trashman. Cans, broken glass bottles, plastic bottles, paper and plastic cups, plastic grocery and trash bags, broken plastic and clay flower pots, bricks, boards with nails, t-shirts, underpants, socks, "bubba" hats, plastic marking tape, ribbons, broken plastic sewer pipe -- I could go on and on about human refuse that washes into storm drains or is tossed in the ravine. The operative word is plastic. Today I spend four hours along a quarter-mile of creekbed. I pass a castoff swimming pool pump and two concrete house piers -- much too heavy for me to pick up -- and carry three full thirty-gallon trash bags and some sheep fencing to our city's landfill. An aluminum beer can partly encased in travertine reveals nature-culture schizophrenia. The creek cements itself with travertine, a natural deposit of lime percolated from our limestone bedrock. Travertine opposes the natural erosion that created it -- a compensating mechanism so typical of the Biosphere -- and by partly damming the creek, provides bathing, drinking, and reproducing pools for animals. But floods destroy this natural cement and grow in number and size as humanity warms the climate, increasing the frequency and intensity of rainfall, while pavement focuses runoff and accelerates erosion. Once the ravine tried to bury refuse but now uncovers unnatural trash.