Quaternary stratigraphy of Norden, a proposal for terminology and classification

Principles and terminology for classification of the Quaternary are discussed, including lithostratigraphy, biostratigraphy. morphostratigraphy, climatostratigraphy and chronostratigraphy. The main conclusion is a proposal for a common chronostratigraphical classification of the Quaternary in Norden (and partly continental NW Europe). The Quaternary is subdivided into the Pleistocene and the Holocene Series. The Pleistocene is further subdivided into several provisional stages (Weichselian, Eemian, etc.), based on the sequence of glacials/interglacials. but with the boundaries preferably defined by stratotypes. The Late Weichselian and the Flandrian (Holocene) are subdivided into chronozoncs (Bolling, Older Dryas, Allerød, Younger Dryas, Preboreal, Boreal, Atlantic, Subboreal, Subatlantic) with the boundaries dcfined in conventional radiocarbon years.     

Holocene humidity fluctuations in Sweden inferred from dendrochronology and peat stratigraphy

Tree-ring and peat stratigraphy data were examined back to 5000 BC in order to identify and compare humidity changes in Fennoscandia. The temporal variation in distribution of Scots pine ( Pinus sylvestris L.) was used as a measure of past lake-level fluctuations in central Sweden. The chronology, which spans 2893 BC–AD 1998 with minor gaps in AD 887–907 and 1633–1650 BC and with additional floating chronologies back to 4868 BC, was cross-dated and fixed to an absolute timescale using a chronology from Torneträsk, northern Sweden. The peat stratigraphy from the Stömyren peat bog, south-central Sweden, was transformed into humification indices to evaluate humidity changes during the past 8000 years. The peat chronology is established by four tephra datings and eight ¹⁴C datings. Synchronous periods of drier conditions, interpreted from regeneration and the mortality pattern of pine, tree-ring chronology and peat humification, were recognized at c. 4900–4800 BC, 2400–2200 BC, 2100–1800 BC, 1500–1100 BC, AD 50–200, AD 400–600 and AD 1350–1500. Possible wetter periods were encountered at 3600–3400 BC, 3200–2900 BC, 2200–2100 BC, 1700–1500 BC, 1100–900 BC, 100 BC-AD 50, AD 200–400, AD 750–900 and AD 1550–1700. The wet and dry periods revealed by the tree rings and peat stratigraphy data indicate considerable humidity changes in the Holocene.     

Holocene palaeoecology and shoreline displacement on the Biskopsmåla Peninsula, southeastern Sweden

High-resolution palaeoecological proxies of pollen, macrofossils and diatoms from an isolation lake provide a long-term record of the Holocene landscape history and shoreline displacement on the Biskopsmåla Peninsula in central Blekinge, SE Sweden. During the Preboreal/Boreal transition, the peninsula was sparsely vegetated by woodlands, along with lateglacial dwarf shrub/steppe communities. The lake basin was isolated from the shallow Yoldia Sea during this time. The regional climate improved from 10 700 cal. BP, evident as progressive expansion of Pinus-dominated mixed forest with deciduous trees. The lake basin was probably connected with the Ancylus Lake during the period 10700–10 100 cal. BP. Subsequently the basin became isolated again, corresponding to the Early Littorina Sea phase. Replacement of freshwater diatoms by those with brackish-water affinity at 8100 cal. BP indicates the initial transgression of the Littorina Sea in this basin. But not until 7500 cal. BP were brackish conditions fully established. Peaks of brackish-marine diatoms and dinoflagellates during 7500–7000 cal. BP indicate increased saltwater inflow to the Baltic Sea in response to global meltwater pulse 3. However, interactive changes in seagrass and stonewort macrofossil concentrations suggest that three minor transgressions during 5900–5300, 5000–4700 and 4400–4000 cal. BP occurred locally, associated with centennial-scale variations in regional wind pattern or coastal storminess. By 3000 cal. BP, the lake basin was finally isolated from the Baltic, and thereafter the landscape on the peninsula became gradually more influenced by human activities.     

Comparative toxicity of drilling muds: role of chromium and petroleum hydrocarbons

Samples of used drilling muds collected during the course of a single well drilling operation exhibited different degrees of acute toxicity to sheepshead minnows and grass shrimp. For moulting grass shrimp, Palaemonetes pugio, the 96-h LC₅₀'s were 360 to 14 560 ppm (μl/litre); many of these values were considerably lower than those reported from previous drilling mud assays. However, when some of the muds used in this study were tested on sheepshead minnows, Cyprinodon variegatus, the resulting 96-h LC₅₀'s (6300 to 100 000ppm) were well within the range of previously reported values.Although a number of the drilling mud samples had relatively high amounts of chromium due to the addition of sodium chromate, there was a low correlation between chromium concentration and toxicity. In only three drilling muds could chromium content alone account for the observed toxicities. Furthermore, chemical analyses revealed the presence of No. 2 fuel oil like petroleum hydrocarbons in the mud samples. Based on the results of toxicity tests with No. 2 fuel oil and the concentrations of oil present in the muds, the toxicity of the mud samples to grass shrimp appears to be largely attributable to the petroleum hydrocarbon content.     

Late Quaternary environmental history of central Prins Karls Forland, western Svalbard

This paper presents the results from stratigraphic and geomorphologic investigations in the Poolepynten area, Prins Karls Forland, western Svalbard. Field mapping, soil profile development and ¹⁴C dating reveal the existence of at least two generations of raised beach deposits. Well-developed raised beaches rise to the Late Weichselian marine limit at 36 m a.s.l. Discontinuous pre-Late Weichselian beach deposits rise from the Late Weichselian marine limit to approximately 65 m a.s.l. Expansion of local glaciers in the area during the Late Weichselian is indicated by a till that locally overlies pre-Late Weichselian raised beach deposits. Stratigraphic data from coastal sections reveal two shallow marine units deposited during part of oxygen isotope stage 5. The two shallow marine units are separated by a subglacially deposited till that indicates an ice advance from Prins Karls Forland into the Forlandsundet basin some time during the latter part of stage 5. Discontinuous glaciofluvial deposits and a cobble-boulder lag could relate to a Late Weichselian local glacial advance across the coastal site. Late Weichselian/early Holocene beach deposits cap the sedimentary succession. Palaeotemperature estimates derived from amino acid ratios in subfossil marine molluscs indicate that the area has not been submerged or covered by warm based glacier ice for significant periods of time during the time interval ca. 70 ka to 10 ka.     

Micro-erosion meter measurements of travertine deposition rates: a case study from Louie Creek,Northwest Queensland,Australia

Although originally designed to measure surface denudation, the micro-erosion meter (MEM) can be adapted easily to measure deposition rates of chemical sediments such as travertines and speleothems. At Louie Creek, northwest Queensland, Australia, travertine deposition rates measured using the MEM average 4·15 mm a⁻¹. However, this figure masks considerable rate variability. Both purely hydraulic and hydraulically related variables appear to be the major mechanisms controlling deposition rates. The most rapid rates occur within relatively high-energy hydraulic regimes (impact and flow zones), whilst deposition rates in pools separating individual travertine barrages (standing water zones) are relatively slow. Dsposition rate variations within spray and impact zones are related directly to discharge. The highest rates in flow zones correlate with the incorporation into the travertine of in situ and allochthonous biogenic material, such as caddis fly larvae, green algal mats and phytoclasts, which proliferate or are entrapped easily under such hydraulic conditions. Considerable spatial variability in deposition rates also prevails. The highest rates for a given set of hydraulic conditions occur at two sites, the Upper Everglades and the Lower Everglades. The MEM also measures net erosion of travertines. At Louie Creek, most of the travertine erosion occurs in the wet season and is confined primarily to standing water zones. © 1997 John Wiley & Sons, Ltd.     

Hydrological changes during the Roman Climatic Optimum in northern Tuscany (Central Italy) as evidenced by speleothem records and archaeological data

Study of the climate in the Mediterranean basin during different historical periods has taken on a particular importance, particularly regarding its role (together with other factors) in the evolution of human settlement patterns. Although the Roman age is traditionally considered a period with a favourable climate, recent studies have revealed considerable complexity in terms of regional climate variations. In this paper, we compare the hydrological change from speleothem proxy records with flood reconstructions from archaeological sites for Northern Tuscany (central Italy). We identify a period of oscillating climatic conditions culminating in a multidecadal dry event during the 1st century bc , followed by a century of increased precipitation at the beginning of the Roman Empire and subsequently a return to drier conditions in the 2nd century ad. The period of rainfall increase documented by the speleothems agrees with both the archaeological flood record as well as historical flood data available for the Tiber River, ca. 300 km to the south. These data also suggest a return to wetter conditions following the 3nd and 4rd centuries ad.     

Near-shore Baltic Ice Lake deposits in Fakse Bugt, southeast Denmark

Shallow seismic, sedimentological and macrofossil data and AMS radiocarbon dates on terrestrial plant remains from submarine deposits in Fakse Bugt in the southwestern part of the Baltic Sea are presented. The sediments were deposited near the shore of the Baltic Ice Lake, mostly in barrier-lagoon environments, during two highstand episodes dated to around 12.5–12.2 ¹⁴C ka BP and 10.6–10.3 ka BP. Coastal sediments from the highstands indicate maximum water levels of 13–15 m and 13 m below present sea level, respectively. During the first episode Salix polaris was widespread in the land area, and during the second episode Dryas octopetala and Betula nana were the most common woody plants. During the lowstand episode Betula pubescens woods dominated. The flora and fauna of the Baltic Ice Lake were rather diverse, reflecting the long and increasing distance to the margin of the Fennoscandian Ice Sheet. Calcium-carbonate-rich, mesotrophic water characterized the Baltic Ice Lake in Fakse Bugt.