Peter White explores Dartmoor's upper Plym Valley

Rabbit warrens, granite quarries, tramways, ancient woodland, remote moorland, wild river: it must be a Dartmoor valley. Add the highest rock faces and the tallest standing stone and it has to be the Plym - a valley full of interest and easy to explore. It falls into two parts. The lower section, between Shaugh Bridge and Cadover Bridge, is deep and wooded with the dramatic rocks of the Dewerstone soaring above the tree canopy. Upstream it is wide open moorland, full of archaeological and historical interest and penetrating deep into the southern plateau.

Let's look at the downstream section first. Cadover Bridge is a busy place, with pretty waterfalls and swimming pools both upstream and downstream from the car parks. Head west on the footpath south of the river and you will soon find yourself in glorious mossy woodland with the river tumbling along below. Where you emerge into more open country there are dramatic views across the valley to the Dewerstone, and you can climb up onto Shaden Moor for a wider panorama extending into Cornwall, and framed by lofty Scots pines. Back on the path, you will have realised by now that you are following an old pipeline which carried china clay slurry from the quarries at Cadover Bridge. As you drop down to Shaugh Bridge there are settling tanks, flat areas which were mica dams and, right by the car park, the remains of the processing plant where, until the 1950s, clay was dried into blocks for transport away.

From the footbridge over the river take the main track which zigzags up the slope to join the line of a tramway, which served the Dewerstone granite quarries until they closed in about 1870. A short way along fork right up a long incline where the granite sleepers of two parallel tracks are still in place. At the top are the remains of the wheelhouse and cable drum which controlled the descent of loaded trucks, which in turn powered the ascent of empty ones! It seems like a lot of investment for some relatively small quarries! Turn right here and follow the upper level of the tramway to its end at the last quarry, from where there is a path to the top of the hill. This was the site of an Iron Age settlement, with a defensive bank around its north side and a fine view of any approaching enemy.

You can look west into Cornwall, across Wigford Down to the heights of central Dartmoor, and down Bickleigh Vale to Plymouth. If you drop down the slope a little you will find even better picnic spots, perched on top of the Dewerstone crags. Here you can watch climbers on routes with names like 'Fly on the Wall' and 'In Extremis Buttress' - names which give a clue to how impressive this place is. Dewer - the devil himself - was well aware of the 45m (150ft) height of the cliffs, and legend tells of how he and his Whist Hounds drove unfortunate victims over the edge to their deaths, so take care! A dramatic landscape, but also peaceful and beautiful, looking down onto the soft tree canopy below, with the sound of the rushing river ever present. When you can tear yourself away, stroll across Wigford Down, past the medieval cross, to Cadover Bridge, with skylarks, buzzards and wheatears for company.

One glance at the OS Outdoor Leisure Map will show that upstream from here is a very different landscape - all moorland, and with an incredibly rich and diverse collection of archaeological features. It is almost all open country, allowing you to wander at will and make your own discoveries. Trowlesworthy Tors give a good overview and in the 19th century were the source of a highly prized red granite, some worked examples of which were abandoned on site. From here an easy route up the valley is along the china clay leat, which, until the recent closure of some pits, provided the water for high-pressure hoses to wash the clay out of the quarry faces.

You may have noticed five warrens named on the map - Ditsworthy, Legistor, Willings Walls, Hentor and Trowlesworthy. The warrening of rabbits was part of the Dartmoor economy from as early as the 12th century right up until 1950. The warrens were enclosed by walls, and rabbits were introduced into artificial buries - long mounds of earth and stone known as pillow mounds, where they bred like... er... rabbits. Dogs were used to drive them into long nets and donkeys transported the catch to the warren house for paunching and dispatch to market. Stoats and weasels were a problem, and the remains of more than 60 ingenious stone vermin traps have been found in the various warren walls. At Ditsworthy, which was the largest warren in England, the warren house and its adjoining kennel field can still be seen. It is a lonely and gloomy place, reflecting what must have been a hard life for the warrener.

The most impressive prehistoric remains can be found around Drizzle Combe. Ritual stone rows, Dartmoor's tallest standing stone at 4.5m (15ft), and a huge cairn 21m (70ft) across known as the Giant's Basin are the highlights, but explore with the map and you will find much more. The whole of this part of the valley is a wonderful archaeological landscape, with the remains of each period superimposed upon those of earlier times. Go there in the evening when the low sun rakes across the hillsides picking out every feature, and you will begin to realise how many stories from the past this valley can tell;