Mendip Hills the hills. The western end of the hills is crossed by the M5 motorway and A38. Further east, and running almost north to south, are the A37 and A39. A wide range of outdoor sports and leisure activities take place in the Mendips, many based on the particular geology of the area. The hills are recognised as a national centre for caving and cave diving, as well as being popular with climbers, hillwalkers and natural historians. Wookey Hole Caves and some of the caves in Cheddar Gorge are open as show caves; however, many of the caves of the Mendip
Somerset Valley and to the south, on the clay substrate, are broad valleys which support dairy farming and drain into the Somerset Levels. There is an extensive network of caves, including Wookey Hole, underground rivers, and gorges, including the Cheddar Gorge and Ebbor Gorge. The county has many rivers, including the Axe, Brue, Cary, Parrett, Sheppey, Tone and Yeo. These both feed and drain the flat levels and moors of mid and west Somerset. In the north of the county the River Chew flows into the Bristol Avon. The Parrett is tidal almost to Langport, where there is evidence of two