Spey Bay

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Best Places to see Scotland’s Geology: Spey Bay

The Spey Bay area around the mouth of the River Spey on the Moray coast is Britain’s best example of a shingle strand plain. The whole area has allowed for the study of the interaction between active and relict coastal and fluvial processes – unlike any other river estuary in Britain today. Active and relict shingle ridges are juxtaposed with other coastal and fluvial landforms that represent the area’s evolution since the end of the last ice age approximately 10,000 years ago.

Spey Bay - the area around the mouth of the River Spey on the Moray coast is Britain's best example of a shingle strand plain. © Scottish Natural Heritage.
Spey Bay – the area around the mouth of the River Spey on the Moray coast is Britain’s best example of a shingle strand plain. © Scottish Natural Heritage.

At the end of the last ice age, a rapid rise in sea level flooded the mouth of the Spey, forming a wide estuarine embayment. Large quantities of shingle were washed onshore as a result of the rising sea levels. This, in addition to the post-glacial shingle being washed downstream, caused the embayment to become infilled (i.e. prograding). As sea levels fell again, an extensive shingle ridge system developed. These relict ridges remain very well preserved and their trend indicates that the orientation of the coastline has switched over time from E-W, to WNW-ESE. The currently active ridges stretch for over 8km along the coast.

Landforms near to the mouth of the River Spey indicate a complex geomorphological history that combines both fluvial and coastal processes. These landforms include raised delta, marine deposits, river terraces, palaeochannels and glacio-fluvial deposits. Active processes include the formation of a shingle spit, a large offshore delta and small areas of salt marsh. Although the evolution has been dominantly progradational, evidence of active regression has been identified in most parts along the complex in recent years.

Further reading:

Gregory, K.J. 1997. Fluvial Geomorphology of Great Britain, Geological Conservation Review Series No. 13, Joint Nature Conservation Committee, Peterborough.