67.
OUR EVER-CHANGING COASTLINE

The coast in the past.
It is hard to imagine that the familiar Moray Firth Coastline that we know today once did not exist. In fact this area has seen many landscapes, including tropical lakes, deserts and ice-age glaciers. The history of the area is written into its coastline. Fossilised fish (56) tell of a warm and arid Scotland, lying south of the equator on the shores of a great lake that extended north to where Orkney and Shetland lie today. Much of the rock dates back 250 million years, to the time of desert sand dunes and early dinosaurs.

Changes in land and sea level have formed many coastal features seen today. Around 18,000 years ago, the area was covered by a vast ice-sheet. As the climate warmed and the ice melted, relieving the land of its crushing weight, it began to rise - and is still recovering today! Meltwater from the ice sheets of Europe and North America caused a rise in sea-level, rapidly overtaking that of the land. At its peak sea-level was about 8 metres higher than it is today. Eroded cliffs and banks set back from the sea, such as those at Covesea, Culbin and Spey Bay, mark previous shorelines. Eventually the sea-level rise slowed and was overtaken by the land, re-exposing tracts of coastal flat-land, such as the Conon valley. Much of the land used today for agriculture, transport, housing and industry once lay under water.

Description of the coastline today.
The combination of geology, past glaciation regimes and present wave and current energy environments have produced a very diverse coastal physiography in the Moray Firth which is still in the process of change. By using the degree of exposure experienced it is possible to subdivide the coastal areas of the Moray Firth into three zones which have very different geomorphological features.

The 'outer' and most exposed sections of coastline, from Helmsdale to Duncansby Head and from River Spey to Kinnaird Head, consist predominantly of cliffs and semi-enclosed bayhead beaches. East Caithness and the extreme south-eastern corner of the Firth have been classified as being 'very exposed'.

The 'middle' coastline lies between Helmsdale and Dornoch Point and Ardersier and Spey Bay and consists of a set of major sand and shingle forelands, including large areas of raised beaches. This coastline includes Culbin Sands(64) which is an excellent example of a large accumulation of fine sands of wind blown origin and amongst the largest of its type in Highland Britain.

The 'inner', low wave energy environments of the Dornoch, Inverness, Beauly and Cromarty Firths, Findhorn Bay, Munlochy Bay and Loch Fleet have extensive areas of intertidal mudflats and saltings of a scale unique in Highland Scotland. Deep infills of sediment occur, for example at Nigg Bay in the Cromarty Firth and at the head of the Beauly Firth. The inner parts of the individual Firths consists of mainly silt- or mud-based sediment but seawards they become increasingly dominated by sand and gravel.

Both the outer and inner coastlines of the Firth are considered to be relatively stable, the inner coast being exposed to a low energy environment and the outer coast being rock dominated and resistant to erosion. The middle coastline experiences the most rapid rates of physiographic change with high levels of sediment transfer.

The importance of the Moray Firth coastline.
The area is of great scientific and educational importance in the study of late glacial, post glacial and contemporary landforms. Several sites are among the most important of their kind in Britain such as the extensive strand-plain at Morrich More with its sequence of raised shorelines, sand dunes and offshore bars which have resulted from accretion over the last 7000 years.

Sources:
Moray Firth Review(86)
Moray Firth Matters - Issue 4(86)