East Bay Walls, Phillip Burton Wilderness

East Bay Walls, also known as the Berkeley Mystery Walls, is a misnomer, as there are many such crude walls throughout the hills surrounding the San Francisco Bay Area, and go as far as Chico and Red Bluff California. In places, they are up to a meter high and a meter wide and are built without mortar; the walls run in sections anywhere from a few meters to over a half mile long. The rocks used to construct the walls are a variety of sizes. Some are basketball-sized rocks, while others are large sandstone boulders weighing a ton or more. Parts of the wall seem to be just piles of rocks, but in other places it appears the walls were carefully constructed. The exact age of the walls is unknown, but they have an old appearance. Many of the formations have sunk far into the earth, and are often completely overgrown with different plants. ()