To the south of Somerset there is an upland with a series of rolling valleys and scarps, from Penselwood in the east to the Blackdown Hills, another designated Area of Outstanding Natural Beauty, in the west. This is a geologically complex area of clays, limestone and marl. The honey-coloured limestone at Ham Hill (also known as Hamdon Hill) is particularly important to geologists because of the assemblages of fossils which it contains, the sedimentary features which it displays and the way it relates to other rocks of equivalent age in the close vicinity. It has been quarried since Roman times at least.