12,000 years ago mid-Wales was in the grip of the last Ice Age. As the climate warmed, the glaciers receded and a large shallow lake occupied this valley. A huge reed bed and woodland developed, but the climate became cooler and wetter, allowing the sphagnum mosses to invade and begin the process of building three raised bogs.
For centuries, the peat was cut by local people and burnt as fuel. Today, Cors Caron is one of the finest raised bog systems in Britain. At first sight, acres of rather dull looking peat bog! But in reality this is rather a special place - special enough for its 2000 acres to be declared a National Nature Reserve.
From the track you can see that parts of the bog surface are slightly domed. This is the result of accumulation of plant material, particularly species of bog moss (Sphagnum) since the valley floor was levelled by glaciers of the last Ice Age.
These raised areas now receive all their water from rain, and have become very acid with a characteristic flora of heather, cross-leaved heath and cotton grasses. The last, with their distinctive white fluffy "flowers" are strictly sedges rather than grasses, distinguished by their triangular stems. The whitebeaked sedge grows through the sphagnum in the hollows on top of the domes. This sedge is the main food of the large heath butterfly.
Around the domes is a zone of less acid ground where the vegetation includes the stiffly erect stalks of yellow-flowered bog asphodel, and the tall creamy clouds of meadowsweet in late summer.
In the summer there is a good array of breeding wetland birds but they tend to be inconspicuous, none more than the skulking water rail. Many more birds come in during the winter including a flock of whooper swans which are less likely to be overlooked.
A number of plants that adapt to the acidic conditions of raised bogs can be found, such as sun-dews, bog rosemary and cotton grasses. The red kite is often seen hovering above the reserve.
ACCESS : Open to all on the walk along the Old Railway, which is suitable for wheelchairs. Permit available for other paths. Allow at least two hours to walk all the Old Railway Track and back from the car park.
The fully accessible circular boardwalk route runs for 1.1 miles (1.7 kilometres) over the south-east bog.
The access to the boardwalk is 450 metres from the main car park along a fully accessible path (the total distance of the return route is 1.6 miles/2.6kilometres).
The route goes past the entrance to an observation building where you can enjoy a peaceful view of the reserve and its wildlife.
There are passing and resting places along the way.
There is some seating along the boardwalk and in the observation building.
Observation tower. Riverside trail by permit. Educational facilities by permit.