A stratigraphical, sedimentologial and palaeoenvironmental analysis of holocene and present-day coastal sedimentation : Wigtown Bay, S.W. Scotland
Griffiths, Ann Hilary
PublisherUniversity of Glasgow
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Evidence of Holocene marine transgression and regression in South-West Scotland is exhibited in the stratigraphical record of present and former coastal deposits. Remnant areas of Holocene coastal (including marine) sediments are preserved at the head of marine inlets and estuaries along the northern shore of the Solway Firth and may extend up to 10km inland, indicating significant changes in coastal configuration as a result of marine transgression and regression during the last 10,000 years.At the head of Wigtown Bay, former Holocene coastal deposits are well exposed along the incised meanders of the upper Cree estuary and Palnure Burn. Referred to in the literature as `carse deposits', these sediments are products of several different environments.During late-Pleistocene times and very early in the Holocene Epoch, the upper Cree estuary area north of Creetown was a low lying boggy environment. The area was marginally marine in character. The exact position of the palaeo-Cree is uncertain but the river flowed in a general NW to SE direction and may have been braided. The marine waters of the Holocene marine transgression flooded northwards, penetrating the upper Cree estuary c . 7,900 years B.P., leading to the deposition of low to high tidal-flats. By 6,480107 years B.P. local regression had begun and seaward progradation of high upper tidal-flats and marsh had started. This environmental situation prevailed until 5,000 years B.P., when incision occurred and terrestrial conditions became dominant.In the lower Cree estuary, waters of the Holocene marine transgression initially flooded the lower courses of rivers and rose to flood the hollows in the uneven surface of the fluvio-glacial deposits flanking the estuary.Accumulation of low tidal-flat deposits gave way to upper tidal-flat and marsh deposits as the transgression diminished. The transgressive event was shortlived. Sediments were deposited at the `feather edge' of the transgression. North of Creetown and the Moneypool Burn, upper tidal-flat and marsh deposits rest directly on fluvio-glacial deposits. As regression occurred, seaward progradation and incision of the carse deposits proceeded.A pause in regression c . 2,000 years B.P. resulted in certain morphological features observed in the Cassencarie area. Stormy conditions resulted in the re-working of marginal fluvio-glacial deposits to form a spit, and to the south (between Cassencarie and Carsluith) coarse marine sands and gravels were transported landwards to form shore-parallel and oblique bars. At Carsluith, similarly-derived material forms a thinly-developed beach blanket. Recession of the sea has proceeded since 2,000 years B.P. to the present-day.