Seashore

View of SS from HG
View from Hope Gap - Alex Tait

The rocky shore platform gently slopes away from the base of the cliff of Haven Brow.
As the cliffs are cut back by waves, the platform is planed off to relatively level surface, although in detail it is irregular, with rock pools, steps and runnels into which the ebb and flow of the tide is channelled.

On the beach you may sometimes find heavy rusty-looking spherical lumps. These are not thunderbolts or meteorites, but the iron sulphide mineral pyrite or marcasite. If broken (take care) they reveal a mass of radiating golden crystals which rapidly oxidise and tarnish - fools' gold!

Flint

Flint consists of a mass of minute crystals of silica. It is black with an outer whitish crust or cortex and occurs in the chalk as nodules (scattered or in bands); or in tabular sheets. Although usually running parallel to the bedding of the chalk, it sometimes fills vertical or oblique cracks. Occasionally you may find sea urchins in which the original calcite shell and soft parts have been replaced by silica and you then have a flint fossil.

The formation of flint has been the subject of considerable debate and although there is no single acceptable theory that explains the origin of all its forms, it seems probable that both physical and chemical processes were involved. On the other hand there is little controversy over its use. An early source of fire made by knocking together two pieces of flint, or flint against pyrites to produce a spark, its splintery nature was also exploited by Stone Age man in the manufacture of his artifacts (tools and weapons) and for crude operations on the brain.

Starfish on a rock
Starfish on a rock - Alex Tait

For hundreds of years its hardness has been used to advantage in the building industry, as for example, in the walls of the Park Centre (roughly trimmed), and Exceat Farmhouse (seashore cobbles in southern facade), and more recently as crushed aggregate for concrete.

Being a very soft rock, the chalk which has fallen from the cliff erodes away from the hard flint which then often accumulates as a shingle beach.

Wave action batters the individual flints together and they become rounded (but rarely spherical) pebbles; in the process they may become stained by minerals in the sea water. Because waves generally approach this coast from a southwesterly direction, the shingle tends to drift along the beach from west to east.

Until the timber-training walls at the mouth of the Cuckmere were built, the river mouth was frequently diverted eastwards towards Haven Brow and evidence of this movement in the past can sometimes be seen today at very low water in the form of a sand bar.

Seven Sisters Country Park
seashore