Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: alluviation

Sortuj według:

Ogranicz wyniki do:

The valley-fill deposits of the Kłodnica River (Southern Poland) : environmental drivers of facies changes from the Late Vistulian through the Holocene

Wójcicki K. J.

Geochronometria

2010

Vol. 35

49-66

Lithological analyses and radiocarbon dating were used to elucidate the patterns and controls of Late Quaternary valley floor development of the Kłodnica River, the Upper Odra Basin. The research results were discussed with data obtained from valleys of rivers draining piedmont basins and highlands of southern Poland. In consequence, five stages of morpho-sedimentary evolution of the Kłodnica valley were distinguished. In the Late Vistulian a large-scale deposition of channel alluvium took place in the conditions of high river discharges. This sedimentary style probably still existed in the Early Pre-Boreal as long as open grass communities survived in the Kłodnica catchment. The next phase, in the Late Pre-Boreal and Boreal, is characterized by a significant increase in accumulation rate of biochemical facies.. The considerable restriction of minerogenic deposition was connected with widespread of forest and gradual limitation of the river discharges. The third stage began at the decline of the Boreal and was defined by decrease of accumulation rate or even biogenic accumulation break. Synchronously, periodic increases of fluvial activity were noticed in the form of cutoffs of meander loops and overbank deposition in oxbows. The beginning of the fourth period took place not earlier than in the Early Sub-Boreal. This stage was distinguished by renewed peat growth/increase in biochemical accumulation rate and periodic increase in alluviation, generally taking place in the conditions of low channel-forming flows. The latest phase (from the Middle Sub- Atlantic till now) is characterized by common initiation of slope deposition and a rapid increase in fluvial sedimentation, especially overbank and tributary fan facies. An increase in minerogenic deposition occurred in response to human impact, which became more significant from the Roman Period and occurred on a large scale from the early Middle Ages. Older settlement phases, including intense settlement from the Hallstatt Period, were not clearly recorded in the Kłodnica valley fill.

Ewolucja doliny Darżyńskiej Strugi jako efekt procesów naturalnych i antropogenicznych

Florek W., Majewski M., Machajewski H., Gałka M., Pajewska J.

Landform Analysis

2008

Vol. 7

43--52

Badany obszar był przez ponad 30 lat przedmiotem zainteresowań archeologów, którzy odkryli tu wielokulturowe stanowisko obejmujące niemal cały okres od schyłku neolitu po wczesne średniowiecze.Wlatach 80. ubiegłego wieku wykonano pierwsze prace geomorfologiczne i geologiczne, które dały obraz daleko idących zmian dna doliny i ich zboczy, ale nie dały jednoznacznej odpowiedzi na pytanie, jakie przyczyny i w jakim okresie je spowodowały.Wostatnim czasie przeprowadzono rozpoznanie paleobotaniczne, które wskazało przede wszystkim na istnienie wielu luk sedymentacyjnych w osadach organicznych, ale dostarczyło też dowody na znaczne przekształcenia środowiska doliny Darżyńskiej Strugi, które dokonywały się zarówno u schyłku plejstocenu, jak i w średniowieczu.

The investigated area has been researched by archaeologists, who discovered a multi-cultural site spanning the period from the latest Neolithic to the early medieval times, for more than 30 years. The first geomorphological and geological study, carried out in the 1980s, led to the recognition of substantial changes in the morphology of the valley floor and the valley sides, but left the question of their causes open. The more recent palaeobotanical prospecting revealed numerous hiatuses in the organic sedimentary record and indicated considerable environmental change in the Darżyńska Struga valley which took place in the latest Pleistocene and in the Middle Ages.In the latest Pleistocene the direction of meltwater drainage was to the south, using a part of marginal esker depression. After the valley of Łupawa was incepted, meltwater eroded a valley tract which is now the lower reach of the Darżyńska Struga. An erosional pavement (bed armour) originated in this way, currently underlying the valley fill. Parallel to climate change and increase in rainfall, particularly after the climatic optimum, peat accumulation commenced. In the Subboreal period Neolithic settlements were established in the proximity of the valley, quickly followed by intense denudational processes. The respective deposit is sandy diamicton of agricultural origin, prograding from the slopes onto the valley floor. Alluviation took place in the Middle Ages, as testified by pollen analysis and macrofossils from peat sediments, and was the consequence of floods redistributing slope sediments over peaty substratum. In the recent times channelization and drainage works have resulted in water level lowering in both the channel and within the floodplain.