摘要:

During the Last Glacial, a very open vegetation existed over western Europe, the tundra‐like vegetation in The Netherlands evolving into a stcppic‐like vegetation towards the Mediterranean. This model was used to analyse the correlation of the Praetiglian (dated from 2.3 to 2.1 million years ago) in northern Europe with the earliest steppic phase in the Mediterranean region. On this basis, stratigraphic relationships between these two areas are postulated for the whole Pliocene and the Early Pleistocene in terms of the vcgctational changes related to the climatic fluctuations. For the first time, correlation has been shown between the palynostratigraphy of northern Europe and the Late Neogcnc marine stratigraphy of the Mediterranean region; moreover, chronological confirmation is supplied by the mammal zonation. the evolution of stratiotes, palaeomagnetic measurements, and K/Ar dates. The conventional Plio‐Pleistocenc boundary occurs during the first interglacial (Tiglian) of northern E

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1983.tb00309.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Products of marine processes occupy a considerable vertical range, which varies along the shore. Extreme waves can both cause erosion and form depositional structures up to several metres above the high tide mark. Temporary supra‐elevation of water level by surge or wave set‐up shifts effects upward. The preservation potential of products of extreme storms is relatively high, when compared to those associated with more frequent events. The level to which coastal landforms develop depends upon the conditions under which they form; thus sand beach ridges which are related to fairweathcr periods have a restricted height range when compared to gravel beach ridges building up under extreme storms. The varied coastal scenery of eastern Ireland provides many examples of storm‐related products (barriers. cliffs, platforms, etc.). They have been related to a latc‐Holocene eustatic sea level or even a partly isostatically controlled raised late‐Holoccne sea level, but both elevations and apparent tilts can be explained by longshore variations in waves, tides and surges. Such an explanation is more consistent with other studies of latc‐Holocene coastal evolution around the Iris

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1983.tb00310.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A regular relationship exists between the growth of lichen species within the SectionRhizocarponandRhizocarpon alpicola.This can be quantified and used to adjust lichenometric dates to take into account differences in the growth rates of the two groups.R. alpicolacolonises deposits later than SectionRhizocarponspecies, although subsequent growth byR. alpicolais rapid. If the two groups arc not separated, important dating errors may arise.

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1983.tb00311.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Lichenometry curves were derived for the glacier forelands of Breidamerkurjokull and Skalafellsjökull using measurements of the collective species,Rhizocarpon geographicum, from independently dated surfaces deglaciated during the period since the late‐19th century ice maximum episode in the area. The form of the curves appears to be linear. Several methods of predicting the ages of undated surfaces were compared for specific test examples, including single lichenometry curves, families of curves and multiple curves based on randomly selected largest lichens. The last method provided a useful means of assessing the reproducibility of predicted ages. Where substrate conditions were highly variable, a lichenometry curve based on single largest lichens provided a preferred resu

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1983.tb00312.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Postsettlemcnt vegetation changes beginning in the early 17th century were studied through comparing stratigraphic peat‐pollen data with available historical evidence. The isolation of the site and the relatively long historical record were ideal for the study. Human disturbance of the vegetation was readily identified in the pollen diagram with a contemporaneous increase in sediment mineral matter. The effects were much the same as the changes associated with Neolithic forest clearance in Northern Europe. Settlement resulted in the introduction and expansion of several cultural weeds after grazing and cultivation ofZea maysbegan on the island in the first decades of the 17th century;Rumex acetosa‐acetosella, Ranunculus acristype,Plantago major‐mediaand several new Compositae and Umbelliferae species all appeared at that time. The response of the native species to settlement was varied. Because of the limitations of the palynologic method, the area of cultivated land and detailed kind of agriculture can only be estimated. The data suggest that although agriculture was intensive from time to time, it took place on a very limited local scale; fires, grazing, and lumbering were the major factors affecting natural ecosy

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1983.tb00313.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Quaternary strata in northcentral Missouri were deposited prior to, during, and subsequent to glaciation of the area. Major depositional units are separated by buried soils. The lower Quaternary Whippoorwill formation is derived from local bedrock and has the intensely weathered New Florence soil developed in it. The pre‐Illinoian McCredie formation, primarily till, is derived from distant shield and local cratonic rocks. The moderately weathered Kingdom City soil within the formation suggests that an intcrglacial separated two ice advances. The lllinoian Lovcland and Wisconsinan Peoria Loesses are derived from Missouri River outwash. Since glaciation, the welded Yarmouth‐Sangamon Soil has developed in till and in lllinoian loess on stable sites but middle and late Sangamon Soils have developed on erosional surfaces. Holocene soils are developed in Wisconsinan loess and alluvium‐coll

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1983.tb00314.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY