It is uncommon in the North Sea basin and northwestern Europe for the ice‐marginal glacial successions of the Middle Pleistocene, Anglian (Elsterian) age to be well preserved and not overridden by subsequent glaciations. The existence of extensive and thick (˜20 m) Middle Pleistocene sand and gravel successions in East Anglia, England, provide a unique opportunity to reconstruct and understand the palaeoenvironmental conditions in the Anglian ice‐marginal zone, and further across the North Sea basin. This paper uses data from 80 sections in two sand and gravel quarries in East Anglia to provide the first evidence concerning: (i) the character of the ice‐marginal processes in the unique, transitional zone between the topographically constrained and unconstrained Anglian ice‐sheet margin; (ii) the role of meltwater in the re‐shaping of topographically driven preglacial drainage; and (iii) the position and the number of oscillations of the Anglian ice‐sheet margin in the form of a sediment‐landform assemblage. Moreover the current research adds to the discussion on the presence and extent of the proglacial lake in the North Sea Basin during the Anglian glaciation. The sand and gravel successions in the Anglian ice‐marginal zone are primarily reworked proto‐Thames sediments deposited by meltwater. At the beginning of the glaciation, the meltwater followed the preglacial (proto‐Thames) river course. However, as the ice sheet advanced, it was re‐routed, overwhelming and abandoning the old river course and depositing an extensive ice‐marginal subaqueous fan. The succession includes evidence for at least two enhanced meltwater release events, as well as indications of glaciolacustrine sedimentation. The character of the described sedimentary settings is discussed in the wider context of the presence of the North Sea Lake.
Although micromorphological terminology has been evolving since 1960, there have been few attempts to create a systematic approach to the description of thin-sections which would serve as a guiding tool for inexperienced researchers, students, and all new to the field of micromorphology. In this paper we present a novel, decision tree based systematic approach for thin-section description. This new approach attempts to unify micromorphological descriptions of Quaternary deposits, regardless of the character of the deposit and the purpose of the analysis.In this research project, named ‘Hidden Ice Worlds’, the micromorphology of an 8 m thick sequence of periglacially disturbed deposits from the Royal Oak Pit, Danbury hill, Essex, UK is described. This sequence is situated on the eastern side of Danbury hill, at c. 50 m OD. Based on micromorphological analyses, a new hypothesis for the evolution of this sequence is presented. Multiple phases of physical reworking associated with freezing and thawing of the deposit, subsequent to Elsterian (Anglian) glaciation (480-420 ka BP) is proposed as the main process responsible for the evolution of the sequence. As periglacially derived deposits are usually removed from such elevated locations on hill' slopes, inversion of the topography is proposed as a necessary factor for the formation and preservation of the sequence described in this atypical location.
Climate change and related sea-level rise pose significant threats to lowland coasts. However, the role of key controlling factors responsible for the frequency and landward extent of extreme storm surges is not yet fully understood. Here, we present a high-resolution sedimentary record of extreme storm surge flooding from the non-tidal southern Baltic Sea, spanning two periods: 3.6–2.9 ka BP and 0.7 ka BP until present. Sediments from coastal wetland, including sandy event layers, were analyzed by sedimentological (grain size, loss-on-ignition, micromorphology), geochronological (14C), geochemical (XRF), mineralogical (heavy minerals) and micropaleontological (diatoms) methods. The results show that both periods were characterized by high-frequency of storm surge flooding, in order of 1.3–4.2 events per century. These periods correlate with phases of enhanced storminess in northwest Europe and took place during both rising and fluctuating sea levels. The study shows that the frequency and landward extent of coastal inundation, largely depended on the development of natural barriers (e.g. beach ridges and aeolian foredunes). Thus, in the context of the future coastal storm-surge hazard, the protection of existing coastal barriers and their morphology is essential.
This paper presents a reconstruction of the marginal zone of the Anglian (Elsterian, 480-420 ka BP) age ice sheet in the Danbury-Tiptree area, East Anglia, UK. The research area is a unique locality where the ice front abutted against a 30km-long and 100-m-tall ridge in an otherwise lowland area. Observations from three main field localities (Danbury quarry, Royal Oak pit and Tiptree quarry) are complemented with ground penetrating radar survey data, borehole data analysis, laboratory analyses and geological map interpretation. A four-stage model of the evolution of the landscape in the Danbury-Tiptree area is presented. The results are of broader importance, in that the sedimentary record sheds light on the processes operating at a constrained ice-sheet margin. The paper identifies the most important characteristics of the depositional environments at an ice front terminating within this type of setting: (i) high temporal and spatial variability of energetic depositional conditions, resulting in the presence of a vast array of distinct depositional sub-environments; (ii) mechanisms promoting differential erosion leading to enhanced topography, and (iii) unusually high overburden pressure in the topographically constrained ice margin within the otherwise lowland area influencing the ice-sheet-bedrock interaction in this particular research area, inducing postglacial seismicity.
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