The second selection of photographs showing details of the rocks in the Upper Kimmeridgian Clay cliff mudstone and shale strata with iron staining on the east side cliffs of Kimmeridge Bay in Dorset, England on the World Heritage Jurassic Coast.
The first selection of photographs taken at Kimmeridge Bay in Dorset, England, yesterday (27 March 2015) showing details of the natural patterns, textures, and colours of the rocks. The rocks are described as rhythmically inter-bedded blocky, organic-poor mudstone and fissile, organic rich shale.
For information about the geology of this location look at:
John C. W. Cope Geology of the Dorset Coast, Geologists’ Association Guide No. 22, Geologists’ Association, 2012, pp 159-167, ISBN978 0900717 61 1.
M. A Woods (compiler) Geology of south Dorset and south-east Devon and its World Heritage Coast, British Geology Survey, NERC, 2011, pp 61 – 67, ISBN 978 085272654 9.
I revisited Redend Point at Studland in Dorset yesterday for the first time in several years. Here are some of the pictures I took. I was only able to look at the north side of the Point because of the state of the tide. The colours seem different from my last trip there. This could be to do with how much rain there has been but also possibly to do with the weathering affect on the iron. [The part of the Point with the wonderful pink and yellow stripes and patterns was further on – to the south of the Point which I could not reach].
More rocks have fallen from the ferruginous sandstone and from the overlying clays. This has brought down a large tree which now lies across the beach. In some areas the sea has undercut the sandstone to produce small caves. These have floors composed of a mixture very fine pale sand, rust-stained flints from the nearby chalk strata around the corner, and bright orange sandstone with pot-holes and eroded channels draining seawards. In this northern part of the Point the colours manifest by the Redend Sandstone seemed less varied than four years ago, and the carved graffiti was much greater than previously noted. Such a shame that almost every surface was disfigured.
Examples of rock texture, colour and pattern in Redend Sandstone (also known as Creekmoor Sand) which is a basal member of the Poole Formation (formerly referred to as the Bagshot Formation), of the Bracklesham Group. The pastel almost rainbow colours are caused by iron staining. Hollow pipes (as in the shot immediately below), which can be up to 15 cm diameter and sometimes extend as much as 4 m through the strata, are of unknown origin. The sandstones were laid down in the Eocene.
Cope, J. C. W., 2012, Geology of the Dorset Coast, Geologists’ Association Guide No. 22, 191-194, ISBN 978-0900717-61-1.
On the eastern flank of the great pebble bank of Chesil Beach in Dorset, on that part adjacent to the Fleet Lagoon where fishermen’s huts are strewn along the water’s edge, the pebbles were sufficiently undisturbed in the spring of 2011 for vegetation to get a grip. A few scattered plants had established themselves amongst the rounded stones; and many pebbles in the same area were coated with slow-growing black or bright orange lichens.
This type of colonisation of beach shingle is a fairly uncommon phenomenon because, in general, the constant movement and abrasion of the pebbles does not allow plants to establish a root system or lichens to encrust the surface of the pebbles themselves. However, in this particular location on the leeward sheltered side of the pebble bank, there had been a period of years of relative stability that enabled vegetation to start growing.
During the winter of 2013 to 2014 the Chesil Bank sustained enormous damage from the storms. The wave action resulted in massive movements of the pebbles. I haven’t revisited the site since the storms but I strongly suspect that the plants and lichens will have suffered and may no longer exist. I must go and check it out. Whatever the outcome of last winter’s weather and subsequent maintenance work on the pebble bank, the slow colonisation process will surely begin again but will take time to restore the habitat to its former situation.