Abstract
Abstract. Depressions (known as deeps) on the Scottish continental shelf are sediment sinks and they, thus, provide important sources of information on past oceanography and climate. Muck Deep is a partially infilled relict glacial valley cut in the continental shelf. A 70 cm core shows an upper buff sandy mud layer (0–4500 BP, radiocarbon years) overlying a dark grey mud layer (4500–12 000 BP). The foraminiferal faunas suggest that the upper sandy layer formed under higher energy conditions comparable to those existing now, where storm waves from southwesterly gales are responsible for transporting material from the adjacent shelf into the deeps. The grey mud formed under lower energy conditions as a consequence of lower storm wave influence on the sea floor (therefore, reduced transport of tests from the shelf into the deep). Because of the interaction of changing sea-levels and glacial rebound, water depths over Muck Deep were 35 m greater at 14–15 ka and have never been less than now. Therefore, the likely explanation of the lower energy deposits at the base of the core is related to the impact of storm waves on sediment transport from the adjacent shelves. Either water depths over the adjacent shelves were too great to be influenced by storm waves or the wave climate (direction) differed at that time.
Highlights
IntroductionThe topography of the continental shelf to the west of Scotland is the most variable of the whole UK continental shelf
The aim of this study is to reconstruct the Holocene palaeoceanographic history of Muck Deep based on the foraminiferal record of a 70 cm long core.The topography of the continental shelf to the west of Scotland is the most variable of the whole UK continental shelf
In the vicinity of Muck Deep, the Quaternary deposits are represented by the Jura Formation which is well-layered acoustically and consists of dark grey silty clays with pebbles and shell fragments
Summary
The topography of the continental shelf to the west of Scotland is the most variable of the whole UK continental shelf It has been moulded by erosional processes, including glacial scour, and by depositional processes, where sediments have buried the bedrock. In the vicinity of Muck Deep, the Quaternary deposits are represented by the Jura Formation which is well-layered acoustically and consists of dark grey silty clays with pebbles and shell fragments. This is a marine deposit as it contains marine foraminifera and dinoflagellates. The lower warm interval may represent the Alleröd interstadial; the cold interval, the Loch Lomond readvance; and the upper warm interval represents Holocene conditions. Peacock & Harkness (1990) concluded that ‘Warming at the beginning of the Holocene Interglacial in the NE Atlantic may have taken place in two phases during the first of which, from 10,100 BP (radiocarbon years) to possibly
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