Dorset is a county of England, situated on the south coast, between Hampshire to the east and Devon to the west.
The main administrative centre is the County Town, Dorchester. This is located in the approximate centre of the county, although the largest towns, Poole and Bournemouth, are to be found to the east of the county, along the Hampshire-Dorset border.
Dorset has a varied landscape, from heathland in the south and east, to rolling downland in the north and west. This landscape and the uses to which it is put are dependent on the underlying geology. The best place to see the foundations of the county is the coast, where erosion by the sea is revealing new outcrops of rock. It is also generally easier to get access to the coast, as opposed to inland sites, e.g. quarries.
The Dorset coastline is it-self varied and has many types of beach and shoreline; again the geology and man influence this.
In Dorset it is possible to walk from the oldest rocks in the west, through the entire Jurassic Marine sequence, and on into the younger rocks of the Cretaceous and Tertiary periods.
The oldest rocks that outcrop on the Dorset coast are found at the Western end of the county. These are the Jurassic shales, mudstones and limestones of Lyme Regis and Charmouth. The rocks here are very striking because of the repeating layers of hard limestone and soft mudstone. They are also very soft and are prone to Landslides, the largest of which is the famous Black Ven landslide complex.
The Liassic Rocks of Lyme Regis.
Because of the gentle eastward dip of the rocks, as you move eastwards you move up the stratigraphic column with the rocks getting progressively younger.
Further East and the sands of Bridport are reached. These sandstone cliffs that outcrop between West Bay and West Bexington are, like the rocks of Lyme Regis, made up of repeating hard and soft bands. This time composed of well-cemented hard sandstone, and much softer sandstone that shows a distinctive honeycomb-weathering pattern.
The Bridport Sands
As the shore is followed south and westwards the cliff line becomes more pronounced with the appearance of the chalk and limestone cliffs of the Isle of Purbeck, so called because it is almost surrounded by water and has very little road access to the rest of the county.
The stretch of coast between the southern tip of the Isle of Purbeck, St. Aldhelm's head, and the resort town of Weymouth has some of the most stunning and important coastal scenery to be found in Dorset. This ranges from the abandoned underground stone quarries of Tilly Whim Caves and Worth Matravers, to the spectacular scenery of Lulworth Cove, a world famous geological and geomorphological site. Between these sites the equally important Kimmeridge Bay is located, with its volunteer marine nature reserve, underwater camera and trail and the type locality for Kimmeridge oil shales.
Worth Matravers Coast |
Abandoned Coastal Quarry at Winspit |
Lulworth Cove |
Stairhole |
Kimmeridge Ledges
The youngest rocks in the county are the Tertiary rocks of the Hampshire Basin. These are characterised by the sands, gravels and clays underlying the heathland of Wareham, Studland, Poole and Bournemouth.
The coast of the Bournemouth and Poole region is made up of sandy beaches and low cliffs, with salt marshes dominating Poole and Christchurch Harbours. Bournemouth and Poole are also the most developed areas and are still growing, which increases the pressure on the fragile heathland, some of which has been designated as a National Nature Reserve, e.g. Studland Heath NNR.
Bournemouth Sea Front |
Poole Harbour |