The quaternary geology and geomorphology of the area between Newark and Lincoln.
|Authors||Howard, Andrew J.|
Four altitudinally distinct sand and gravel bodies between Newark and Lincoln provide evidence of major drainage diversion during the Quaternary. In order of decreasing altitude they are: the Eagle Moor; Balderton; Fulbeck; and Floodplain Sand and Gravel. In addition a new deposit, the Skellingthorpe Clay is recognised. The Eagle Moor Sand and Gravel is interpreted as a cold stage proximal braided river deposit of Anglian age, aggraded by a mixture of waters from a meltwater enriched River Trent and direct outwash from a glacial snout. Beneath the Eagle Moor Sand and Gravel, close to Lincoln, is the Skellingthorpe Clay which is interpreted as a proglacial lake deposit also of Anglian age. The Balderton Sand and Gravel is interpreted as a proximal braided river deposit aggraded during diversion of the Trent through the Lincoln Gap by Wolstonian ice occupying the Lower Trent Valley. The Fulbeck Sand and Gravel is a composite deposit aggraded by a stream entering the Lincoln area from the south. It is composed of warm stage Ipswichian sediments deposited probably in a meandering river, through to early Devensian cool interstadial sediments, deposited in a single thread channel. The Floodplain Sand and Gravel contains a variety of depositional environments ranging from basal braided river sediments, deposited during the Devensian cold stage, through to meandering Holocene river sediments. A new model of drainage evolution for the area is proposed starting from the Early Pleistocene and accepting the hypothesis of easterly flowing master streams draining to the North Sea through the Lincoln and Ancaster Gaps. Anglian glaciation, disrupted the drainage pattern and excavated the Trent Trench subglacially. Retreat of ice to the north of Lincoln diverted the Trent towards Lincoln Gap aggrading the Eagle Moor deposit. The onset of temperate conditions (the Hoxnian) allowed the Trent to find a new course across lower ice scoured terrain to the Humber Estuary. The Wolstonian marked a return to colder conditions and the formation of glacier ice in the Lower Trent Valley diverted the river towards the Lincoln Gap. Melting of this ice mass associated with climatic amelioration of the Ipswichian, allowed the Trent to resume a course to the Humber Estuary which was probably stable through the early and middle Devensian. Development of late Devensian (Dimlington Stadial) ice north of Lincoln, diverted the Trent along the Till Valley and through the Lincoln Gap. Climatic amelioration and removal of ice from the Lower Trent Valley at the end of the Devensian allowed the course to the Humberto be re-established. The Fulbeck River appears to have long history of stability and flowed north to the Lincoln Gap from at least Late Wolstonian to Early Devensian times. This work indirectly has implications for the stratigraphic framework of Britain. Firstly, the assignment of the Balderton deposit to a pre-Devensian cold stage indicates that it is not associated with early Devensian ice and the development of a high level ‘Lake Humber’. Secondly, the Balderton deposit indicates that for part if not all of the Wolstonian, the area was not affected by major glaciation. This is further substantiated by the lithological signature of the sands and gravels which indicate no new input of exotic material since the Eagle Moor stage (the Anglian).
|Keywords||cold stage proximal braided river deposit ; Climatic amelioration; Fulbeck River|
|Publisher||University of Derby|
|Web address (URL)||https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316633|
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|Deposited||10 Oct 2019, 13:58|
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