This review focuses on the development of the 'Little Ice Age' as a glaciological and climatic concept, and evaluates its current usefulness in the light of new data on the glacier and climatic ...variations of the last millennium and of the Holocene. 'Little Ice Age' glacierization occurred over about 650 years and can be defined most precisely in the European Alps (c. AD 1300-1950) when extended glaciers were larger than before or since. 'Little Ice Age' climate is defined as a shorter time interval of about 330 years (c. AD 1570-1900) when Northern Hemisphere summer temperatures (land areas north of 20°N) fell significantly below the AD 1961-1990 mean. This climatic definition overlaps the times when the Alpine glaciers attained their latest two highstands (AD 1650 and 1850). It is emphasized, however, that 'Little Ice Age' glacierization was highly dependent on winter precipitation and that 'Little Ice Age' climate was not simply a matter of summer temperatures. Both the glacier-centred and the climate-centred concepts necessarily encompass considerable spatial and temporal variability, which are investigated using maps of mean summer temperature variations over the Northern Hemisphere at 30-year intervals from AD 1571 to 1900. 'Little Ice Age'-type events occurred earlier in the Holocene as exemplified by at least seven glacier expansion episodes that have been identified in southern Norway. Such events provide a broader context and renewed relevance for the 'Little Ice Age', which may be viewed as a 'modern analogue' for the earlier events; and the likelihood that similar events will occur in the future has implications for climatic change in the twenty-first century. It is concluded that the concept of a 'Little Ice Age' will remain useful only by (1) continuing to incorporate the temporal and spatial complexities of glacier and climatic variations as they become better known, and (2) by reflecting improved understanding of the Earth-atmosphere-ocean system and its forcing factors through the interaction of palaeoclimatic reconstruction with climate modelling.
Celem badań było rozpoznanie głównych etapów późnoglacjalnej i holoceńskiej ewolucji doliny Czarnej Nidy, która przecina dwie jednostki fi zycznogeografi czne: Góry Świętokrzyskie i Nieckę ...Nidziańską. W pracy szczególna uwaga poświęcona jest zapisowi zmian klimatu i działalności człowieka w rzeźbie i aluwiach.
W obrębie dna doliny Czarnej Nidy w jednym poziomie morfologicznym występuje szereg włożeń różnowiekowych. Włożenia te były formowane przez rzekę o różnym rozwinięciu koryta - roztokowym (vistulian) - makromeandry (późny glacjał) - układy wielokorytowe (eoholocen, subatlantyk) - małe meandry (holocen). Spowodowało to też różnice w wykszatałceniu aluwiów tych systemów, co zostało uchwycone dzięki analizom litofacjalnym i granulometrycznym.
Ogólne tendencje późnoglacjalno-holoceńskiego cyklu erozyjno-akumulacyjnego nawiązują do prawidłowości znanych z dolin środkowej Europy i opisanych w licznych pracach. Oprócz ponadregionalnych faz powodzi, np. w mezoholocenie około 6200 BP, występują ślady lokalnych, pojedynczych zdarzeń ekstremalnych, które modelują zlewnie niższego rzędu. W dolinie nie zostały rozpoznane wyraźne ślady wzrostu aktywności fl uwialnej związanej z rozprzestrzenieniem się prehistorycznego hutnictwa żelaza w okresie rzymskim.
Dane z doliny Czarnej Nidy oraz analiza literatury z innych dolin środkowoeuropejskich wskazują na to, że koncepcja E. FALKOWSKIEGO (1971, 1975), dotycząca poźnoglacjalno-holoceńskiej transformacji koryt niżowych: rzeka roztokowa - wielkie meandry - małe meandry - rzeka roztokowa, może być stosowana również do rzek średniogórza. Powinna jednak zostać uzupełniona o holoceńskie systemy wielokorytowe (anastomozujące, rozgałęzione) funkcjonujące w eoholocenie i subatlantyku, które są coraz częściej opisywane także w innych dolinach europejskich.
Studies on the impact of climate and human activity on evolution of river valleys, in various timescales, have been being conducted for many years in various academic centres (e.g. TROLL 1957; STARKEL 1960; FALKOWSKI 1967, 1975; SCHIRMER 1974; BECKER, SCHIRMER 1977; KOZARSKI, ROTNICKI 1977, 1978; SZUMAŃSKI 1977, 1982; ALEXANDROWICZ ET AL. 1981; STARKEL, THORNES 1981; FLOREK 1991; KALICKI 1991; VANDENBERGHE 1992). Today these problems have not lost anything from their topicality, which could be proved by numerous programs (e.g. INQUA-GLOCOPH, FLAG, PAGES), conferences, and publications from the last years (e.g. VANDENBERGHE, MADDY 2001; KLIMEK 2003; KUKULAK 2004; STARKEL 2005; KALICKI 2006; KOBOJEK 2009; NOTEBAERT, VERSTRAETEN 2010.). Prehistoric changes of the environment, both natural and anthropogenic, may be a base for forecasts in conditions of recent climatic changes and increasing anthropogenic pressure.
Hitherto studies concentrated on investigations of main valleys, e.g. the Vistula river valley, in several parts, published in 6 volumes ‘Evolution of the Vistula River Valley during the last 15 000 years’ in the years 1982-1996 and summarized in a monograph (STARKEL 2001). A row of published monographs concerned particular regions of Poland, e.g. the region of Łódź (TURKOWSKA 1988), Pomerania (FLOREK 1991), Bieszczady (KUKULAK 2004), or the entire Central Europe (KALICKI 2006). However, majority of these studies were focused on rivers of the first or second order, and only a few of them concerned rivers from the belt of uplands and old mountains (e.g. KLIMEK 1996, 1999, 2003; ŚNIESZKO 1985; TEISSEYRE 1991; MICHNO 2004; WÓJCICKI 2005, 2010).
In the Holy Cross region the investigations on this subject were conducted in a few sections of valleys (among others the valleys of Świślina, Psarka, Belnianka, Nida, Kamienna) in the 1950s and 1960s, and in the upper, source section of the Czarna Nida (in the fourth-order valleys of Lubrzanka and Belnianka) in the 1990s (LUDWIKOWSKAKĘDZIA 2000, KOWALSKI 2002a, b).
The present study is an attempt of filling a gap in the Polish literature on this subject; regional on the one hand, and this concerning identification of record of the climate changes and the anthropogenic pressure in morphology and alluvia of the lower, third-order river systems on the other.
U radu je prikazano istraživanje u podmorju sjevernog Jadrana i priobalja južne Dalmacije unutar naslaga pliocena, pleistocena i holocena. Njime su opisane postojeće litostratigrafske jedinice u ...taložinama rijeke Po u Hrvatskoj i određene takve jedinice u prostoru taloženja rijeke Neretve. Oba taložna prostora bila su pod utjecajem promjena razina mora, posebice tijekom kvartara, što se znatno odrazilo u smanjivanju dubine mora i povećanju površine kopna tijekom oledaba, posebice u sjevernom Jadranu. U hrvatskom dijelu Padske depresije navedene su dvije formacije – Istra (pliocen) i Ivana (pleistocen, holocen). U formaciji Ivana opisana su tri člana, poimence Anamarija, Katarina i Izabela. Dalje prema jugu, u priobalju južne Dalmacije, imenovana je nova formacija Neretvanski kanal (za taložine pliocena, pleistocena i holocena). Ona je zatim podijeljena u pijeske Neretva (koji mogu biti ekvivalent i cijele formacije) te član Malostonski zaljev (kvartarne starosti). Isključivo pliocenski tipski litotip nije opisan.
We investigated 2500 years of community succession in Cladocera from the sediments of a mountain lake (Lake Piramide Inferiore) located in the Khumbu Valley close to Mt. Everest in the Nepalese ...Himalayas. Our objective was to determine late Holocene changes in cladoceran species composition and abundance in a biogeographical context and with respect to previous proxy-based paleolimnological data (algal pigments and organic content). The results suggested that cladoceran fauna of Lake Piramide Inferiore was species-poor and dominated by Chydorus cf. sphaericus throughout the sequence. The sediment profile recorded the occurrence of Alona guttata type individuals, which were attributed to Alona werestschagini Sinev 1999 based on their morphology and the species' current distributional range, and this was the first record of its presence in the Himalayas. In addition, a periodic long-term succession of melanic Daphnia (Ctenodaphnia) fusca Gurney, 1907 and non-melanic D. (Daphnia) dentifera Forbes 1893 was observed in the sediments. The millennia-long cladoceran community changes, although subtle due to the C. cf. sphaericus dominance, were in general agreement with the previous proxy-data of lake productivity following the regional paleoclimatic development and apparently partly driven by bottom-up mechanisms. The periodic occurrence and success of D. fusca and D. dentifera throughout the late Holocene in Lake Piramide Inferiore, combined with the knowledge of their phenotypic properties (i.e. carapace melanization) and previous investigations on their contemporary and past distribution in Khumbu Valley, suggested that they may have responded to altered underwater UV radiation regimes. Furthermore, they may have even periodically excluded each other subsequent to changes in the underwater UV environment. The results indicated the usefulness of fossil cladoceran analysis as a tool in biogeographical research, since the occurrence of species in space and time can be observed through sediment records and taxonomic identity of the remains may be resolved with the help of regional faunal distribution.
During the last stages of the Weichselian glaciation (ca. 9,000-15,000 years B.P.), reduced ice loads and glacially affected stress fields resulted in active faulting in Fennoscandia with fault ...scarps up to 160 km long and up to 30 m high. These postglacial (PG) faults are usually SE dipping, SW-NE oriented thrusts, and represent reactivated, pre-existing crustal discontinuities. Postglacial faulting indicates that the glacio-isostatic compensation is not only a gradual viscoelastic phenomenon, but also includes unexpected violent earthquakes, suggestively larger than other known earthquakes in stable continental regions. We explore here possibilities and benefits for investigating, via scientific drilling, the characteristics of postglacial faults in northern Fennoscandia, including their structure and rock properties, present and past seismic activity and state of stress, as well as hydrogeology and associated deep biosphere. The research is anticipated to advance science in neotectonics, hydrogeology and deep biosphere studies, and provide important information for nuclear waste disposal, petroleum exploration on the Norwegian continental shelf and studies of mineral resources in PG fault areas.
Ljubljansko barje je izjemna pokrajina. Vlažne hidrološke razmere omogočajo dobro ohranjenost arheoloških najdišč in paleoekološkega zapisa. Vendar pa je Ljubljansko barje za paleoekološke ...raziskave hkrati tudi izjemno zahtevna regija. Razvoj holocenske pokrajine in vegetacije je bil namreč zelo dinamičen, posledica tega pa spremenljive tafonomske razmere in, zaradi kompleksne hidrološke mreže in človekovega vpliva (rezanje šote), pogosto fragmentiran paleoekološki zapis. Kljub številnim raziskavam v zadnjih desetletjih, podrobne raziskave nekdanje hidrologije niso bile opravljene, čeprav je za arheologijo in paleoekologijo to očitno pomembna tema, saj se je v zadnjih letih razvila živahna diskusija o tem, ali je območje Ljubljanskega barja nekoč pokrivalo jezero ali rečna poplavna ravnica. S tem prispevkom se želim vključiti v razpravo in predstaviti svoj pogled na hidrološko problematiko. Moje mnenje je, da so bile paleoekološke razmere na področju Ljubljanskega barja preveč kompleksne, da bi jih lahko zreducirali samo na polemiko “jezero ali poplavna ravnica?”, moj glavni očitek raziskovalcem, ki so dozdaj razpravljali o tej temi pa, da je njihova interpretacija hidrološkega dogajanja preveč ambiciozna, ker temelji na rezultatih premalo ob-sežnih paleoekoloških raziskav, pa najsi gre za rezultate njihovih lastnih raziskav ali interpretiranje rezultatov drugih raziskovalcev.
Kubischta, F., Knudsen, K.L., Ojala, A.E.K. and Salonen, V.-P., 2011. Holocene benthic foraminiferal record from a high-arctic fjord, Nordaustlandet, Svalbard. Geografiska Annaler: Series A, Physical ...Geography, 93, 227-242. DOI: 10.1111/j.1468-0459.2011.00434.x
This study presents the results of benthic foraminiferal analyses of a marine core record from about 100 m water depth in the fjord environment of Isvika bay, Nordaustlandet, Svalbard. During the Last Glacial Maximum, the bay was glaciated by the north-western sector of the Svalbard-Barents Sea Ice Sheet. The foraminiferal assemblages reflect glaciomarine conditions during deglaciation and early Holocene (about 11-250-9640 cal. yr bp) followed by glacier-distal environment in an open fjord with relatively high influence of Atlantic waters from the open ocean (9640-7430-cal. yr bp). A subsequent foraminiferal indication of a glacial advance was followed by deposition of a diamicton unit within a short time period at 5800-5700 cal. yr bp. The mid- and late Holocene were characterized by assemblages indicating restricted open-ocean connection and gradually more severe conditions, which are considered to be caused partly by a gradual cooling and freshening of the Atlantic water inflow to the shelf area and partly by a continuous isostatic uplift of the area. The foraminiferal record shows that the environmental changes in Murchisonfjorden are not just an effect of changes in solar insolation but are also influenced by local processes, as well as changes in the Atlantic water inflow to the northern Svalbard shelf and to the fjord via Hinlopenstretet.
High resolution pollen analysis of a peat bogs (Rascafría, Valle del Lozoya, Madrid) allowed to reconstruct the dynamic of the vegetation comunities of the last 2455 ± 60 BP, as well as the anthropic ...signals from the Prehistoric to the present time. A paleolandscape of pasture dedicated to transhumant and transterminant cattle activities define different levels of anthropic pressure. This study reveals the importance of the use of the pollen and non-pollen (NPP) proxies of anthopic activity in the determination of the palaeoecological conditions and human impact on the environment, allowing in this example, to characterize the livestock and the identification of the changes in the trophic status of the peatbog.
El analisis polínico de alta resoluición de un testigo obtenido en una formación higroturbosa de origen periglacial situada en el termino municipal de Rascafría (Valle del Loyoza, Madrid, España), ha permitido recontruir la dinámica de las comunidades vegetales y el impacto antrópico de los últimos 2455 ± 60 BP, mediante la utilización de los denominados indicadores polínicos de antropización, especialmengte las asociaciones de los palinomorfos nitrófilos de caracter antropozoógeno y antrópico con los microfósiles no polinicos de afinidad coprófila.
The retreat record of the tabre lacier into the orra torfjället mountains, after separation from the massive ärnaån lacier at some undetermined time in the tlantic hron, is documented by recessional ...moraines in the foreland. While poorly constrained by radiometric dating, the age of the middle group of moraines averages out to less than 4000 cal
14
yr , the older moraine group probably of ate tlantic age, with the youngest deposits of ittle ce ge. Soils/paleosols range from ntisols (youngest) and nceptisols (middle group) to mature podosols (outer group), existing either as single-story profiles or within pedostratigraphic columns, buried pedons either surfaced with weathered glacial or mass wasted deposits. Some profiles exhibit convoluted properties which could place them in the ryosolic order. The physico-mineral-chemical properties of soils/paleosols in recessional deposits across this sequence provide weathering indices over the mid to ate olocene in the wedish sub-rctic climate. It is likely the middle group of deposits represents stillstand of the retreating glacier offset by climatic deterioration with the onset of Early eoglacial climate which altered the glacial mass balance, at least until termination of the . Correlation to other alpine areas in the middle and tropical latitudes with similar records is attempted and discussed. While the tabre lacier disappeared after the , the nearby ärna lacier remains extant on the land surface, a presumed result of slight elevation differences between the two cirques which affects storm tracks and resultant variations in glacial mass balances.
In Alaska, lichenometry continues to be an important technique for dating late Holocene moraines. Research completed during the 1970s through the early 1990s developed lichen dating curves for five ...regions in the Arctic and subarctic mountain ranges beyond altitudinal and latitudinal treelines. Although these dating curves are still in use across Alaska, little progress has been made in the past decade in updating or extending them or in developing new curves. Comparison of results from recent moraine-dating studies based on these five lichen dating curves with tree-ring based glacier histories from southern Alaska shows generally good agreement, albeit with greater scatter in the lichen-based ages. Cosmogenic surface-exposure dating of Holocene moraines has the potential to test some of the assumptions of the lichenometric technique and to facilitate the development of a new set of improved lichen dating curves for Alaska.
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