yellow and green hills

Here in NE Cali we are surrounded by the hot, dry, flat desert, but on clear days (which is most days actually) in the distance you can glimpse mysterious yellow and green patchwork hills. They almost look like a mirage. Last weekend we set out driving towards this mirage and found ourselves at Lake Barryessa on the highway to Napa. We decided to do what looked like an easy 4 mile loop hike, which turned out to be a 5 mile hike where the first 4 miles were a steep incline (and the last mile was such a steep decline we thought we should be skiing). We found ourselves precariously following the path up and down the tops of the hills. The views were incredible. The yellow in the hills is dried grass, and the green is sturdy shrub-like aromatic trees. We couldn't figure out why the grass and shrubs arrange themselves in stripes along the hillside though. More pictures here.