摘要:

Shane, Linda C. K. 1987 03 01: Late‐glacial vegetational and climatic history of the Allegheny Plateau and the Till Plains of Ohio and Indiana, U.S.A.Boreas, Vol. 16, pp. 1–20. Oslo. ISSN 0300–9483.Pollen evidence from the Allegheny Plateau and the Till Plains south of the Great Lakes shows marked post‐glacial vegetation gradients.C. 15,500–11,000 B.P.: On the Plateau, spruce forest was rapidly established, persisted for 2,000 years, then began a gradual change to deciduous‐conifer forest. On the Till Plains, open spruce forest tundra closed slowly over 1,000 years, declined rapidlyc. 13,500 B.P., and a deciduous open woodland developed.C. 11,000–10,300 B.P.: On the Till Plains, a brief cooling is recorded by increases in the abundance of spruce and fir, contemporaneous with the European Younger Dryas. No clear change is seen on the Plateau.10,300–4,000 B.P.: Warming and/or drying occurred in both areas, as hemlock and jack/red pine trees immigrated, followed by white pine. Conifers disappeared from the Till Plains by 9,800 B.P., but pine and hemlock trees may have persisted on the Plateau. After 10,000 B.P. mixed deciduous forest was established across the entire region. Between 8,000 and 4,000 B.P., further warming/drying is indicated on the Till Plains with development of open oak forest and lake shallowing, and on the Plateau by a minor increase in herbs, lake shallowing, and re

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00750.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Kullman, Leif 1987 03 01: Sequences of Holocene forest history in the Scandes, inferred from megafossilPinus sylvestris. Boreas, Vol. 16, pp. 21–26. Oslo. ISSN 0300–9483.Altogether 5414C‐datings of megafossilPinus sylvestrisL. from above the present tree‐limit in the southern Swedish Scandes were evaluated. The samples were discussed in relation to the present‐day tree‐limit of pine. Pine reached almost 200 m higher than at present shortly after deglaciation and remained at very high altitudes until at least 4,000–3,50014C years B.P. The conclusion was that the precise biological and climatological interpretation of these regionally sampled data is still obscure. It is impossible to judge whether clusters of megafossil pine represent periods relatively favourable for pine growth and reproduction or merely periods advantageous for production of dead wood and its long‐term preservation. In terms of climate, these alternatives reasonably implicate widely diffe

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00751.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Sejrup, Hans Petter 1987 03 01: Molluscan and foraminiferal biostratigraphy of an Eemian‐Early Weichselian section on Karmøy, southwestern Norway.Boreas, Vol. 16, pp. 27–42. Oslo. ISSN 0300–9483.At Karmøy, southwestern Norway, a section with marine sediments from the last interglacial (the Avaldsnes Interglacial) and from two ice‐free periods (the Torvastad and Bø Interstadial) in the Weichselian have been examined for molluscs and foraminifera. The following conclusions concerning the depositional environments of these sediments can be drawn: (1)The Avaldsnes Interglacialwas a high‐energy environment with a sea level 20 to 50 m higher than at present, regressing towards the end of the interglacial. Sea temperatures were as in the area today or slightly warmer. (2) During theTorvastad Interstadial(71–85 ka) the sea level was between 0 andc. 20 m higher than at present, and sea temperatures were as between Svalbard and northern Norway today. (3)The Bø Interstadial(40–64 ka) shows a complete interstadial cycle, with changing sea level and temperatures. Its optimum was close to the conditions prevailing in North Norway today or slightly colder. By comparison with other sites, a total of at least four interstadial episodes through the Weichselian in southwestern Norway is proposed. These date toc. 30 ka, 40–64 ka, 71–85 ka and 87–101 ka. The episodes and the glacial advances between them do not directly correlate with published interpretations of changes in surface circulation in the Norwegian Sea through the Weichselian. It is suggested that the nourishment of the southern part of the Scandinavian ice sheet might be more related to sea surface conditions in the North Atlantic than to tho

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00752.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Prentice, I. Colin, Berglund, Björn E.&Olsson, Tommy 1987 03 01: Quantitative forest‐composition sensing characteristics of pollen samples from Swedish lakes.Boreas, Vol. 16, pp. 43–54. Oslo. ISSN 0300–9483.Surface pollen percentages of major tree genera in 53 moderate‐sized lakes in south and central Sweden were compared with percentages of mean forest volume derived from survey plots within 5, 10, 20, 50 and 100 km of each lake. A maximum likelihood extended R‐value method was used to estimate relative slopes and intercepts of the pollen‐tree relationship at each forest sampling radius. Slopes generally went up and intercepts down as sampling radius was increased. Visual goodness‐of‐fit was optimal at 5–10 km forPiceaand at 50–100 km forPinus, consistent with theoretical pollen source areas.Fagusgave good visual fits at all radii, butQuercusgave indifferent fits andBetulaandAlnuspoor fits. The taxa differed in relative pollen representation, with relative R‐values on the order of 0.11 forPicea, 0.90 forFagus, 1.0 forPinus, 1.5 forQuercus, 2.3 forAlnusand 2.5 forBetula. Regional forest patterns can be reconstructed from lake pollen spectra by applying R‐values, but the ‘region’ represented depends on each taxon's pollen dispersal characteristics and spatial pattern. The R‐values given here could be used to calibrate European Holocene pollen spectra from moderate‐sized lakes for

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00753.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Vandenberghe, Jef, Bohncke, Sjoerd, Lammers, Wim&Zilverberg, Liesbeth 1987 03 01: Geomorphology and palaeoecology of the Mark valley (southern Netherlands): geomorphological valley development during the Weichselian and Holocene.Boreas, Vol. 16, pp. 55–67. Oslo. ISSN 0300–9483.The actual area of the Mark valley is limited by the borders of an Early Weichselian erosion phase. The subsequent accumulation has resulted in the formation of a Weichselian Pleniglacial terrace which has been deeply dissected by Late Glacial erosion. The present alluvial plain is formed by Late Glacial and Holocene infilling. The maximum incision of the Late Glacial fluvial phase was reached slightly before 11,780 B.P. and involved locally dry conditions which have given rise to aeolian activity during this period (Older Dryas). On the deepest parts of the Pleniglacial terrace, a backswamp environment was established until the end of the Alleröd. At the beginning of the Younger Dryas the river invaded the terrace but shortly afterwards aeolian activity progressively increased. At the climax of the Younger Dryas, deep seasonal frost or local permafrost characterized the Mark va

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00754.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Book reviewed in this article:Gibbard, P. L. 1985: The Pleisrocene History of the Middle Thames Valley.Joakim Donner, Department of Geology, University of Helsinki, Snellmaninkaru

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00755.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Bohncke, Sjoerd, Vandenberghe, Jef, Coope, Russell&Reiling, Rudo 1987 03 01: Geomorphology and palaeoecology of the Mark valley (southern Netherlands): palaeoecology, palaeohydrology and climate during the Weichselian Late Glacial.Boreas, Vol. 16, pp. 69–85. Oslo. ISSN 0300–9483.A backswamp peat, located on an Upper Pleniglacial terrace, has been analysed in detail with respect to its pollen content, its macroscopic plant remains and its fossil insect fauna. The analyses permitted a detailed reconstruction of the Late Glacial palaeoenvironment besides an estimation of fluctuations in the local humidity and fluctuations in the palaeotemperatures. The main boundaries in the sequence have been radiocarbon dated, indicating a peat accumulation fromc.12,600 B.P. to 10,970 B.P. The Böllings.l. shows a clear migration of vegetation belts, starting with a shrub vegetation and passing into a birch wood. This progressive vegetation development culminates in a short lasting Pinus maximum early in the Alleröd, without being hampered by events during the Older Dryas. Up to and including the Alleröd no serious climate deterioration is registered. The humidity curve reveals a semiterrestrial phase in the local hydrosere that correlates with the Older Dryas and that is explained by the geomorphological evolution of the adjacent river system. The transition to the Younger Dryas coincides with a return to fluvial conditions and a marked change in the pollen record and insect fauna, indicating a decline in the average July temperature from between 18 and 15°C to 11 a

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00756.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00757.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Book reviewed in this article:Thermophysics of glaciers: Zolikov, I. A. 1986: The Thermophysics of Glaciers.Matti Seppala, Department of Geography, Uniuersity of Helsinki

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00758.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:0300-9483    

DOI:10.1111/j.1502-3885.1987.tb00759.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY