COASTAL ZONE ASSESSMENT SURVEY - SCAPE

3. THE PHYSICAL ENVIRONMENT OF THE STUDY AREAS
3.1 Late Quaternary landforms and environments on Kintyre
3.1.1 In general there is great uniformity in the geological formations along the east
Kintyre coastline, and this has had an important role in shaping the character
of this coastline, which is of notable outstanding scenic beauty. The geology
within the study area is mainly dominated by Precambrian age metamorphose
schists associated with the Dalradian Metamorphic Assemblage (Macgregor
1965). These rocks are mainly metamorphosed marine sediments that produce
a rugged coastline with often steep coastal gradients. At various points along
the coastline, igneous dykes outcrop at the shore. The dykes are
predominantly composed of basaltic olivine-dollerite and are of Tertiary age.
These features are very resilient to coastal erosion and in general they vary in
height from between 0.5-3m and extend well beyond the mean low water
spring tide (MLWST).
3.1.2 At the risk of oversimplification, the internal structural weaknesses within the
schists, typically areas such as joints, fractures and faults, exert a primary
control on both the morphology and rate of cliff erosion in many areas. These
zones of weakness provide areas where accelerated wave erosion has formed
embayments, arches and sea-caves as well as smaller irregularities in the
coastline within the study region (cf Steers 1973). In general terms the rate of
cliff erosion and the resulting landforms are related to both cliff-forming
materials and the physical processes to which they are exposed. Although the
study area lies in a reasonably sheltered sea-loch environment within the
Kilbrannan Sound, storm surges and dominant south westerly wind-driven
wave action continue to shape this area of coastline.
Raised marine shorelines
3.1.3 As with much of the Clyde region, a rock platform occurs above the present
tidal limit along much of the Kintyre coast. The relict shorelines have been
mapped extensively and are depicted on the modern solid and drift edition
1:50 000 produced by the British Geological Survey (BGS). The older 1 inch
seventh series maps also produced by BGS depict the three main raised
shorelines, namely the low, medium and high raised beach. Isostatic recovery
has altered the altitude at which these features now rest. Between Skipness
and Claonaig, a former intertidal platform up to 150m wide is visible and is
largely covered by Juncus wetland (Firth and Collins 2002). Typically these
platforms are backed by relict cliff lines (e.g. Smerby Rocks NR 760 232). In
other areas, the intertidal platform is less well defined (e.g. Port Righ NR 8170
3795) but is better preserved at the sheltered heads of small embayments.
Other platforms possibly attributable to the Loch Lomond Re-advance and
more recent Holocene age storm levels are more common above the mean high
water spring tide (MHWST) and the backshore area. These are often more
pronounced in areas where softer marine sediments have been redeposited or
where areas of Devensian age till have been remodelled as a result of higher
sea levels during the Maximum Marine Transgression.
KACL/997/0
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CFA