Postglacial Marine Transgression Research Articles

Late Quaternary Evolution of Coastal Sand Barriers, Port Stephens-Myall Lakes Area, Central New South Wales, Australia

AbstractThe geomorphic and stratigraphic history of six coastal embayments has been studied in the vicinity of Newcastle, New South Wales (N.S.W.), Australia, in order to determine modes of deposition, and the degree to which marine and estuarine deposits can be correlated and dated. Each embayment possesses its own distinctive suite of landforms ranging from those dominated by coastal dunes to those in which beach ridges occur. In four of the bays dual sand barriers, comprising an Inner Barrier and an Outer Barrier, provide the framework for correlation between embayments. Six stages are recognized in the deposition of late Quaternary sediments in this area: (i) Pre-Last Interglacial, involving accumulation of separate composite units consisting of estuarine clays and transgressive dune complexes; (ii) Last Interglacial stage during which Inner Barriers were formed; (iii) Last Glacial reworking of barrier and dune sands by westerly winds; (iv) Postglacial Marine Transgression during which the Outer Barriers were initiated; (v) Mid-Holocene stage following cessation of sea-level rise ca. 6000–6500 yr B.P. on this coast, and involving progradation of Outer Barriers in some embayments; and (vi) Late Holocene episodic eolian reworking of dune complexes and Outer Barriers. The relatively high wave and wind energy as well as the tectonic setting of the central N.S.W. coast results in somewhat different geomorphic histories from barrier-island coasts in North America and Europe.

Stratigraphy and chronology of receding barrier‐beach deposits on the northern Illawarra coast of New South Wales

Abstract Four Quaternary units occupying a shallow bedrock depression have been delineated from outcrop exposures and auger drilling on Sandon Point Beach, North Bulli, 60 km south of Sydney, N.S.W. In ascending stratigraphic order these units are: a basal muddy sand (2.2+ m) of fluvial origin; a mottled mud (3.5 m) with common iron oxides, representing alluvial deposits with a superimposed soil profile developed during a period of lower sea level; a sandy mud (3.9 m) containing estuarine shell fossils, small tree stumps (including one mangrove) and abundant wood fragments; and, at the top, a pebble layer overlain by beach and dune sands, all partly indurated with iron oxides (2.3 m). 14C dating in situ tree stumps, shell material and wood fragments from the estuarine sandy mud unit between mean sea level and +1.45 m provided ages ranging from 7520 ±. 150 to 6350 ± 100 years B.P. The age of this unit is supported by a date on in situ Myrtaceae root material (7000 ± 150 years B.P.) from a similar study sandy mud unit at Thirroul, some 2 km north of the Bulli site. These dates indicate that sea level reached its present position between 7500 and 6500 years ago and thus record the final stages of the postglacial marine transgression on the southern coast of New South Wales.

Late Quaternary terrigenous and carbonate sedimentation on Grand Bank of Newfoundland

Grand Bank is a shallow, flat-topped bank more than 100,000 km2 in area that is separated from the Avalon Peninsula of southeastern Newfoundland by the deeper Avalon Channel. The channel and innermost bank are covered by a gravel facies ; petrologic evidence shows that this facies was deposited by the late Wisconsin Avalon ice cap, which extended part way onto the bank. A seaward-fining quartz sand facies covers the rest of the bank and extends beyond the shelf break; petrologic evidence shows that this facies was derived by erosion of the underlying Mesozoic-Tertiary coastal plain succession during postglacial marine transgression. Skeletal carbonate (mainly barnacles) has been accumulating on Grand Bank since the Holocene rise in sea level cut off its supply of all but minor ice-rafted terrigenous sediment. The Holocene carbonate fraction is in hydraulic equilibrium with the older terrigenous fraction, which, along with textural, petrologic, and other features, show that these palimpsest sediments are being reworked and mixed in response to the modern hydraulic regime. The seaward-fining textural pattern probably has also developed in response to modern processes, possibly by storm-induced bottom currents. The results show that (1) combinations of source lithologies and depositional processes have interacted to produce a “classical” systematic decrease in grain size and corresponding increase in grain roundness and compositional maturity across the bank, (2) sediments of different ages and origins are readily mixed on this shelf, and (3) processes not related to glaciation form sedimentary deposits on a higher latitude continental shelf.

Late Quaternary sea-level changes, Gulf of Carpentaria, Australia

A review of data from offshore bauxite exploration in the Gulf of Carpentaria has led to a refinement of the sea-level curve of Bloom and others. It is suggested that the Gulf of Carpentaria was a basin of internal drainage from about 47,000 to 26,000 B.P. and 23,000 to 11,000 B.P., after which the sea rose to its present level. Between 26,000 and 23,000 B.P., the gulf was connected to the open sea. The period of the postglacial marine transgression in the gulf, from about 11,000 to about 6500 B.P., compares with the sea-level envelope of Thorn and Chappell.

Formation of Palimpsest Sediments, Conception Bay, Southeastern Newfoundland

Grain-size analysis of 74 samples shows that gravel, very fine sand, and mud populations compose the principal bottom sediments in Conception Bay, southeastern Newfoundland. These individual populations, plus mixtures of the populations, gives rise to 11 textural types. The sediments were deposited as glacial drift during periods of lower sea level and then reworked into discrete particle-size populations during postglacial marine transgression. Subsequent deposition of the winnowed finer grained populations as distinct sedimentary units in deep water and upon coarser lag deposits in shallower water resulted in the variety of textural types. These are defined by Swift and others (1971) as palimpsest sediments. A model proposed for formation of the 11 textural types in Conception Bay is probably applicable to other formerly glaciated inlets. The relation between mean size and sorting (standard deviation) of the trimodal sediments is complex because there are several possible combinations of mixing of particle-size populations. Analysis of this relation is useful for identifying sediments composed of mixtures of particle-size populations.

Palaeoecology of post-glacial beaches in East Lothian

Synopsis Molluscan assemblages, not previously described in detail, from raised beaches in the Aberlady and Gosford Bay areas indicate that several facies are present: rocky shoreline deposits formed at high-water mark; sandy shore facies from a little lower in the shore zone; a sandspit and various intertidal and estuarine deposits. In addition there are fossil life assemblages of Ostrea edulis and Cerastoderma edule. The raised beaches are correlated on the evidence of their depositional facies combined with their present height O.D., from which have been determined the relative heights of high-water marks at the times of their formation. The older life assemblages and the highest shoreline (8–9 m O.D.) have thus been grouped together and by means of C14 dating found to be about 5500 years old, corresponding with the age of the main post-glacial marine transgression in the Firth of Forth area.

Stone tools from a washing-limit deposit of the highest Post-Glacial transgression, Lealt Bay, Isle of Jura

NR 662902. Pollen analysis demonstrates that vegetation was broadly comparable in the post-glacial period along the NE coast of Jura and in mainland Argyll, while the highest post-glacial marine transgression is proved to have reached about 51ft OD on Jura early in the Atlantic period. Excavation at Lealt Bay yielded about 50,000 stone artefacts from the old marine deposit c 47ft OD; these show a variety of forms in use over a long period, and a few bear evidence of two phases of use separated by an appreciable time-gap. Microliths predominate and include the small backed blade, small crescents, triangles and quadrilaterals, and tanged and hollow-trimmed forms. The remaining material includes hafted blades, steep scrapers, thumb-nail scrapers, gravers, tanged leaf-shaped flakes, and a transverse series ranging from petit tranchet to heavy triangle types. The site is interpreted as a landing-place and camp for hunters from the mainland from before about 4250 BC and including occupation of Neolithic date (see also 70/754). A R

The Post-glacial marine transgression in N. Ireland-Conclustion from Esturine and raised beach deposits: A contrast

Studies of the raised beaches in Co. Down have suggested a water level of + 30 ft. (9.2 m.) I.O.D. in the Atlantic period (c. 8,000-5,000 B.P.).
 Stratigraphical, palynological and radiocarbon investigations of estuarine deposits in Co. Down indicate that the maximum of the post-glacial relative sea-level rise was shortly before 3,000 B.P. when high-water reached to 12 ft. (c. 3.6 m.) above present mean sea-level. The regression since the maximum is apparently of the order of 4 ft. (c. 1.2 m.). These findings stand in contrast to earlier tentative conclusions from open coast 'raised beach' studies that the sea rose at its maximum to c. 22 ft. (6.46 m.) above mean sea-level before 5,000 B.P.

The relationship of the raised strandlines and main end-moraines on the Isle of Mull, and in the district of Lorn, Scotland

During the deglaciation of Northern Argyllshire, embracing the Isle of Mull and the district of Lorn, the ice margin of the Highland Ice Cap readvanced on two successive occasions. Each of these glacial stages are associated with an apparent fall in sea-level of over 40 ft.—the result of continued isostatic rise of the earth's crust. The younger, or Connel stage, is believed to correspond to the Younger Dryas Period of about 10,000 years ago. The earlier, or Ford stage may be considerably older. The evidence presented suggests that they cannot be the same age. After the ice had disappeared, isostatic uplift continued during the period of the post-glacial marine transgression. The highest strandline of this period was found to coincide in part with the notch of a ‘pre-glacial’ wave-cut platform at about 28 ft. above sea-level.

POSTGLACIAL MARINE SUBMERGENCE IN CENTRAL ARCTIC CANADA

In the Canadian Northwest Territories west of Hudson Bay, the postglacial marine transgression was more extensive than in any other part of North America. Although there are numerous isolated observations of strand lines and other raised marine features, there has been no systematic study of the maximum depth of this sea and the form of the subsequent emergence of the land. Measurements made during 3 summer9s field work in the area show that on the mainland the sea reached a depth of 360–400 feet. On the islands in the north of Hudson Bay the depth was 550–650 feet. The difference is explained by unequal waning of the ice sheet. In the western part of the Thelon and Dubawnt basins a large proglacial lake preceded the invasion of the sea. The lake fell by clearly defined stages. Subsequent emergence from the sea was continuous until the final 100 feet when there were two periods of temporary stability. There is widespread evidence that the land is still rising. In the areas that were submerged, unconsolidated debris has been reworked by wave action into beaches, spits, bars, and other shoreline features. Along the shallower coasts these have completely changed the character of the landscape. The marine transgression did not last long enough to produce erosional features in consolidated rock.