Query: Are the pebbles a natural phenomenon?
These messages were originally posted on the My Brighton and Hove messageboard . They are reproduced here because the topic is of general interest.
Are the pebbles a natural phenomenon, or were they put there to stop erosion? If so, when, and where did they come from?
Sue Cornish, 30/07/2001
Pebbles are moved along the South Coast by longshore drift. This combination of prevailing wind and tidal current moves material from West to East. Whenever there is a cliff fall the chalk gets washed away and the embedded flint, being much harder rolls around the sea floor getting rounded.
Sometimes the flints get trapped in sand or clay for a few thousand years. In this case the pebbles are stained brown on the outside. Pebbles that have been trapped in chalk get stained white. Blue (grey) flints have not been stained at all and are prized by the pottery industry as they can be crushed and used as a glaze. Baskets of these were often collected for sale by poor people in the 19th century. Thus it can be seen that pebble movement can be entirely natural and can protect the coastline from further erosion.
Where man has interfered with the natural processes by building Newhaven Harbour arm or Brighton Marina pebbles have to be transported to depleted beaches (as at Seaford) in order to restore the protection to the coastline.
A very interesting video of the replenishment of Seaford beach can be viewed or obtained from the Martello Tower Museum on Seaford Seafront (open Weds, Sats & Suns).
Tame Ferret, 31/07/2001
- Natural occurrence
- Flint eroded out of chalk cliffs. The soft friable chalk got bashed up by the sea and harder flint remained, and rolled into their circular shapes by the action of the sea and the pebbles grinding against each other.
- Certain amount of longshore drift whereby the pebbles moved into a eastward direction by the action of the waves, so the flint may have originated from chalk cliffs in West Sussex.
Tricker questions to answer are how the flint got into the chalk in the first place, and how the chalk is formed. See more information on my web sites:
Recommended Book: Pebbles on the Beach by Clarence Ellis (Faber) ISBN 0 571 06814 6 pbk. There is also a local booklet by Dr Malcolm Cornwall about pebbles on the beach, probably published by the University of Brighton.
by Andy Horton, 01/08/2001
I believe that originally the beaches at Brighton were sandy. I have seen several old prints which show this. According to my history lessons at school in Brighton (some years ago now) much of the sand was removed for use in building (to mix with cement) before there was any regulation of this sort of extraction of natural resources. So although the pebbles are in fact natural, the beach itself has been substantially altered by human action.
by Jon Davies, on 01/08/2001
If these pebbles are ‘a natural occurrence’, why then are they only seen on the beach section and stop when the water begins? If you look from the pier, you will see clean sand – not one pebble in sight! Also, there is not enough current or even wave movement to generate the movement of these pebbles by ‘long shore drift’. If this does happen, then surely we would see many pebbles in the ocean and not clean sand. I agree with the comments made by Jon Davies.
by Cassandra Garmston, 02/06/2003