摘要:

The paleoenvironmental evolution of a Dutch deltaic swamp forest area during the mid‐Holocene was strongly governed by a general rise of water level (bound to postglacial sea‐level rise) and by fluctuations in this water‐level rise. A phasing of this 2,000 years period shows alternation of closed swamp forest on the one hand, and (fluvio‐) lacustrine environment with swamp forest islands on the other. The refined scale of investigation permits bird's‐view landscape reconstructions. These also show how attractive the area was for neolithic

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00914.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:Geology today. A magazine from Blackwell Scientific Puhlications Ltd

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00915.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Thirteen lake basins isolated during the Late Weichselian and Holocene are studied. The lakes are situated in two study areas, one on the west coast and one on the south coast of Norway. The diatom, genusFragilariashows a predominance in sediments deposited around the isolation independent of when the basins were isolated. The highest percentages may occur before, during or after the actual isolation from the sea based on diatom taxa other thanFragilariaspp. Predominance ofFragilariaspp. seems to develop in accordance with the local environment and more or less independently of the regional differences. The largeFragilariaabundances might be caused by the same effect as in recently deglaciated basins situated above marine limit in Late Weichselian, mainly dependent on the nutrient supply.SummaryA diatom analytical study has been made of eight lakes in Hordaland, western Norway and five lakes in Telemark, southern Norway, to investigate their changing environment during isolation from the sea. These lakes have been isolated at different ages, spanning from BØlling in Late Weichselian to Subatlantic in Holocene. The aim of the investigation was to determine whether regional differences or differences in time of isolation would affect the general trend in the development of such basins. The rate of the isolations is more rapid in Late Weichselian and Preboreal than in the remaining Holocene. The pH‐values and trophic status indicate a development from nutrient rich (alkaline and eutrophic) to nutrient poor (acid and oligotrophic) conditions, regardless of geographical position.Large abundances ofFragilariaspp. occur around the isolations. Peaks inFragilariaspp. may occur before, during or after the isolation from the sea. ThereforeFragilariataxa are not good isolation indicators for detailed stratigraphic investigations. It is evident that a predominance ofFragilariaspp. may occur in any chronozone. In the two areas investigated there is a tendency forF. construensto reach its highest frequency values in basins isolated between 10,000 and 8,000 years B.P.Large abundances ofF. pinnataare not restricted to specific chronozones and the species appear to have a wide salinity range.F. virescens var. subsalinais also present from BØlling to the Subatlantic chronozone and indicates a preference for saline water. It seems plausible that the large abundances ofFragilariaspp. around the isolation levels are mainly caused by the same effect as in recently deglaciated basins above the marine limit in Late Weichselian and seems to be dependent on the nutrient supply. The predominance ofFragilariaspp. seems to develop according to the local ecology of the separate basins more or less independently of the regional differen

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00916.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A review is made of earlier work and theories on a formation of string mires, together with a report on detailed investigations carried out over seven years on a small string (aapa) mire in eastern Finland, to determine the applicability of earlier hypotheses on the explanation of string and pool patterning. Attention is paid to the topography of the surface and bottom of the mire and to the peat and pollen stratigraphy. Results are presented of year‐round temperature measurements and long sequences of snow and frost depth readings from both pools and strings. Snow depth is shown to be a decisive factor in ground frost formation. The strings are shown by a series of repeated Geodimeter measurements to move partly upslope, partly downslope and partly in a sideways direction. The maximum cumulative movement recorded was about 1 m in seven years. Some of the pools remained unfrozen even in midwinter because of groundwater flow. Uneven retention and discharge of the surface water causes the strings to be in a labile state and promotes their movement. The initial formation of the string and pool topography is dated to 2,000–3,000 radiocarbon years B.P. and attributed to a rise in the groundwater table due to climatic change. The resulting fluviodynamics of the mire surface led to the accumulation of loose material into ramparts at the spring flood season and led in time to differential peat formation conditions, progressive peat accumulation on the strings, and regressive peat degradation in the pools. Thus the strings became higher and the pools deeper. The authors believe the importance of frost action, ice expansion and solifluction on the development of string and pool patterns is frequently overestima

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00917.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:Lowe. J. J.&Walker M. J. C. 1984. Reconstructing Quiiternary environments

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00918.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Foraminifera from four boreholes through Quaternary deposits at Roar, Skjold and Dan in the central North Sea have been examined. Shallow marine Eemian deposits were represented over the whole area, and at Roar marine deposits from an older glacial period were found below the Eemian. A glaciolacustrinc sequence occurred above the Eemian in all the boreholes, and at Roar this unit was succeeded by marine sediments containing arctic to boreo‐arctic foraminiferal faunas. Both the non‐marine and overlying marine units are referred to the Weichselian. Marine Flandrian deposits occur in the upper part of the borings and the faunal succession through this sequence is descri

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00919.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A sequence of Middle Pleistocene (approximately early ‘Cromerian Complex’) sediments has been subdivided into subglacial, proximal glaciomarine, distal glaciomarine and marine facies. The subglacial facies represents lodgement till deposited during the final stages of ice‐sheet advance. At the onset of ice‐sheet retreat, streams deposited their load into a shallow‐water; glaciomarine environment; gravelly sediments immediately in front of the ice‐grounding line and finer material, in suspension, to more distal areas. Ice‐rafting, slumping and traction currents were also active within the glaciomarine environment. The lithofacies characteristics of this sequence are consistent with deposition from a grounded tidewater ice‐sheet. The glacigenic succession is restricted to the Forth Approaches area, which implies that the ice‐sheet had a limite

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00920.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:Genoways, Hugh&Dawson, Mary (eds.) 1984: Contributions in Quaternary Vertebrate Palaeontology: A Volume in Memorial to John E. Guilday

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00921.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:1984: Quaternary Science Reviews Vol. 2. 327 pp.

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00922.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY