Buckinghamshire is one of the smaller English counties, yet one of the most varied, attractive and interesting historically. It falls into two quite distinct and separate halves, on either side of the chalk scarp of the Chilterns. To the north is a rural countryside of rounded hills, clay vales and brooks, with ancient towns such as Buckingham and Olney. The south is a series of steep sided, often dry valleys and ridges on the dip of the Chilterns sloping down towards London and the Thames Valley, with old towns such as Amersham, Beaconsfield and Eton.