Description: A feature of the upper valley of the River Dove is the row of sharp-edged limestone hills which line the north side of the river almost like teeth. These hills, notably Chrome Hill and Parkhouse Hill, are the remains of coral reefs which once made up the edge of the shallow lagoon in which the limestone rocks were laid down on the early Carboniferous era, 340 million years ago. They are among the most spectacular sights of the area. (information from www.cressbrook.co.uk)