Sunday, 13 September 2015

Revisit: Land's End Peninsular September 2015

The bay experiences a dynamic regime, alternating between periods of erosion (stony) and deposition (sandy).The underlying substrate is boulders and bedrock, however, variable amounts of sand may be deposited on top, sourced from the sand bar situated offshore. The communities encountered reflect the alternation between these regimes.

Please see previous blog posts:

On my most recent visit in September, 2015 the shore was starting to show the signs of Autumn with winnowing of finer sediments from the upper shore and an increased strandine reaching across the entire cobble and boulder beach. Some seaweeds also showed signs of seasonal die back.

The rocky shore during the current visit in September, 2015 shows little variation from June, 2015 except in the upper shore, where there has been erosion and winnowing of finer sediments and the formation on a strandline across the entire cobble and boulder beach.

The rocky shore in June 2015, does not support a strandline across the entire cobble and boulder beach.
The strandline that filled the cave in June, 2015 is no longer visible, only a wedge of seaweed behind the boulder can be seen. However, the height of the sand in relation to the boulder suggests that there has been increased deposition of sand within the cave since June and it may be that this sand has covered the strandline that was present or, the seaweed has now been washed up to form the strandline across the cobble and boulder beach?

The strandline present within the cave in June 2015. 

Again the strandline present on this section of the shore in June, 2015 has now gone and the finer sediments present in June and April, 2015 have been winnowed from between the cobbles and boulders.
Seaweed in June, 2015 had been washed up among the boulders of this part of the shore. 

This photograph taken in April 2015, shows the finer material that once occurred on this part of the shore and has now been winnowed away.

Fucoids begin to show seasonal die back. The lost fronds contribute to the strand line.