摘要:

In the Flandrian Fenland sediments of the Nar Valley, Norfolk, an upper clay and thick upper peat overlie lower clay and lower peat units thinning eastwards up the valley. Lithostratigraphic and altitudinal variations in less than thirty metres led to the application of a soil mechanics technique, the oedometer test, to the sediment units in order to estimate amounts of compression and corrections for the altitudinal displacements. The principles and assumptions behind the oedometer test are reviewed and results from compression tests on Flandrian Fenland deposits in the Nar Valley discussed in relation to interpretation of stratigraphic data, especially in terms of reconstruction of former sea levels. Limitations of the technique, particularly with reference to peats, are discussed.

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00883.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A 56 cm long core covering ca. 9,000 years was obtained from a small, unnamed lake (78°29.5'N, 4 76°46.8'W) at 295 m elevation, innermost Baird Inlet, Ellesmere Island. The vegetation is high arctic, but locally relatively rich, with areas ofCassiope tetragona–Empetrum–Vaccinium uliginosumheath on the steep slopes above the lake. Cores were taken from the basin centre through ca. 15 m of water. Basal sandy‐silt is overlain by 51 cm of laminated silty‐gyttja and fine detritus gyttja grading upwards to loose algal gyttja. Three radiocarbon dates indicate rates of sedimentation from 0.07 to 0.04 mm per year. Pollen concentration varies from 1,500 to 2,000 per cm3in the lower part of the core to 100 to 200 in the upper part; calculated pollen influx is between less than one and 14 grains per cm2per year. Four local pollen assemblage zones reflect an early pioneer phase (grass‐sedge‐Oxyria) in the lowermost organic sediment, followed by the appearance and spread ofSalixsome 8,000 years ago and then, some 7,000 years ago, by a rise in Ericales. A period of vegetational stability with dwarf‐shrub heaths follows, lasting for over 3,000 years. The topmost zone shows some increase in indicators of bare ground and fell‐field vegetation (Saxifraga, Ranunculus, Papaver, Caryophyllaceae,Dryas) and decline in pollen influx, hence deterioration of local conditions during the last 3,5

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00884.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Variations in composition between and within Saalian till types of The Netherlands are demonstrated with reference to grain‐size distribution, fine‐gravel petrography and heavy‐mineral composition. Several factors explain different aspects of the compositional variations. Firstly, a compositional layering results from differences in the amount of local material that has been assimilated in successive till hands. Secondly, a petrographic stratification is present in the erratic components, which is most strikingly expressed by the occurrence of flint‐poor till overlying till rich in flints. This feature is interpreted to have been inherited from an englacial debris stratification which is related to the distribution of source rock types in the up‐glacier area. Finally, a predominantly lateral variation in till composition is present, reflected best in the assemblages of the indicator pebbles, resulting from deposition by ice streams of different source and directio

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00885.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

This paper is concerned with the size variation of thalli of the lichenRhizocarpon geographicumagg. on intermoraine surfaces in the proglacial valley of Austerdalen, southern Norway, and with the use of thallus dimensions for both relative and absolute dating of intermoraine deposits. Measurements of the five largest lichens in 200 m2search areas at 255 sites show significant cross‐valley and down‐valley variations, with the smallest thalli located towards the centre of the valley and at up‐valley sites. This variation has been examined in greater detail by dividing the intermoraine areas into twelve morphological zones, for which geomorphological and stratigraphical relations enable the construction of a relative time sequence of formation. This relative time sequence was then found to he confirmed by mean values of measurements of the largest lichen thalli in 100 m square quadrats within each morphological zone. This approach has allowed not only the relative age of morainic and intermorainic deposits to he established from geomorphological evidence but also, using tentative dates for the moraines, the construction of a chronology of moraine and intermoraine depositional e

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00886.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:Cihazi, A. (ed.) 1983:Palaeoclimatic Research and Models. Report and Proceedings of the Workshop held in Brussels.

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00887.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Till lithology and transport distance were studied along five transects running in the direction of ice flow and intersecting the N‐S‐oriented Kuhmo Greenstone Belt, which is some 5 km in width. A total of 531 stone counts were performed on three fractions (>20 cm, 6–20 cm and 2–6 cm) in 162 pits dug with a mechanical excavator. An experimental model is developed for predicting the transport distances of clasts in basal tills. It shows the traditional method of expressing transport in terms ofhalf‐distance(i.e. the distance at which the proportion of a given rock type in the till has been halved from what it was at the distal contact of a given rock type in the bedrock) to be dependent upon the width of the source unit in the bedrock, varying in the present case from 0 km to 16 km as the width of the source belt increases from 0 km to infinity. The Kuhmo Greenstone Belt being 5 km broad, the mean half‐distance for the transport of stones and boulders in the till is 2 km, the boulders having been moved somewhat shorter distances and the pebbles longer distances. It is recommended that transport distances for till material should be expressed in terms of therenewal distance(i.e. the distance over which the proportion of a new rock type increases from 0% to 50%). In the Kuhmo area this distan

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00888.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The Quaternary deposits of south Cornwall are described with an emphasis placed on the loess component. A formal lithostratigraphic name – the Lizard Loess – is proposed for the loess formation with a holostratotype designated from the Lizard Peninsula. Two environments of loess deposition are distinguished on the basis of geomorphic position and degree of solifluction activ

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00889.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The terminology of the genusRhizocarpon, as used by lichenometrists, is at present confused and vague. The failure to differentiate even to the section level has resulted in errors in dating and has made the comparison of growth rates derived for different parts of the world difficult, if not impossible. The use of a standard nomenclature would clarify the degree of species differentiation that has been attempted in any given study.

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00890.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:Wright. H. E., Jr. (ed.) 1983:Late‐Quaternary Environments of the United States. Vol. 1The Late Pleistocene, edited by Stephen C. Porte

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00891.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A stratigraphically recorded transgression deposit from a bog at 50 m above sea level near Lödöse, north of Gothenburg, has been analyzed with a view to determining its isolation course. Pollen and14C analyses were used for dating, and the interpretation of water‐level changes and isolation were based on diatom analysis. The transgression phase began at about 10,000 years B.P. and the basin was isolated before the time of the rational Corylus limit (C°), which in this area is at about 9,700 years

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1985.tb00892.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY