At the end of Covington Street, in the Sheffield Village neighborhood, you’ll find a little parking area and a public access to the Dunsmuir Ridge Open Space. (It’s also the back entrance to the Dunsmuir House property.) Take the dirt road up the hill and you’ll pass this textbook exposure of the soil profile: dark topsoil on top, pale subsoil beneath. But keep going; this is one of Oakland’s most secluded public spaces. Sheffield Village is one of Oakland’s prettiest neighborhoods, all built in the late 1930s except for the higher houses on upper Revere Avenue, above the Hayward fault.