Raised shorelines and the ice limits in the inner Moray Firth and Loch Ness areas, Scotland*

• Main Author: Firth, C.R.
• Format: Other/Unknown Material
• Language: English
• Published: Coventry University 1984
• Subjects: late Glacial; Flandrian; Scotland; sea level changes; deglaciation; glacio-iostatic adjustment; Cromarty; Dammed Lake; Loch Lomond; Ice Sheet
• Online Access: http://curve.coventry.ac.uk/open/items/0bae8e8b-dd93-4751-b3a1-2d5b84d5ef79/1

This thesis provides an assessment of the changes in relative sea level during the Lateglacial and Flandrian in the inner Moray Firth and Loch Ness areas. All identifiable marine, fluvial and glacial features and deposits below lOOm O.D. were examined by detailed morphological mapping; and all terrace fragments were accurately levelled. Local sequences of relative sea level movements and deglaciation events are outlined. Correlation of shoreline fragments is aided by height-distance diagrams. In the inner Moray Firth area 10 raised marine shorelines related to the deglaciation of the Late Devensian ice sheet are recognised. Each shoreline declines in altitude towards N25 E. The sequence of shorelines indicates that during deglaciation relative sea level fell. Deglaciation occurred rapidly in the deep water channels of the Moray, Inverness, Beauly and Cromarty Firths, whilst in the narrow valleys (Ness, Conon, Orrin, Glass) limited ice wastage was associated with substantial falls in relative sea level of at least 19m at Inverness, 13m at Balblair and 6m at Muir of Ord. During the Loch Lomond Stadial relative sea level remained stable in the area and extensive marine erosion formed the Main Lateglacial Shoreline. Advance of ice during this period initiated a lacustrine transgression in Loch Ness. Subsequently, during ice decay, the drainage of the ice-dammed lake in Glens Spean and Roy temporarily raised the level of Loch Ness by circa 4m. During the Flandrian, an initial fall in relative sea level was replaced by a rise which culminated in the formation of the highest Flandrian shoreline at 9m O.D. Subsequently relative sea level fell towards present level forming 5 successively lower shorelines. Correlation of Lateglacial and Flandrian shoreline sequences with those in other areas of Scotland is attempted. The implications of the shoreline sequence to glacio-isostatic movements is also evaluated.