For a Named Coastline Examine the Effect of Rock Type and Structure on Coastal Landforms

The coastline I have chosen is part of the world heritage site (the Jurassic Coast), from Old Harry Rocks to St Oswald’s Bay

Discordant Coast - the structure and alignment of these rocks have a significant effect on the landforms produced. This is a discordant coast where the geological sequence has produced distinctive coastal landforms.

At Old Harry/Ballard Point and at Durlston Head are outcrops of rocks resistant to erosion. The chalk escarpment which bends from St Oswald’s Bay eastwards to Old Harry increases in width to produce steep 60 metre cliffs. Erosion at the chalk headland of Ballard Point has produced stacks, wave cut platforms, notches, caves and arches.

The more resistant Portland limestone has also produced vertical cliffs and caves. It is more resistant to erosion than the chalk. Both outcrops produce pronounced headlands. The much softer Greensand and Wealden beds have been eroded more rapidly creating a large bay (Swanage Bay) between these headlands.

Concordant Coast - whilst the geology essentially remains the same, the structure here is different. This is a concordant coast with unique coastal landforms, The outer layer of the concordant structure is made up of a thin layer of Portland limestone.

At stair hole the Portland limestone had been punctured in several places.