Quaternary River Diversions in the London Basin and the Eastern English Channel

Abstract

The principal river of the London basin, the Thames, has experienced a number of course changes during the Quaternary. Some, at least, of these are known to result directly from glaciation. In the early Quaternary the river flowed to the north of London across East Anglia to the north coast of Norfolk. By the early Middle Pleistocene it had changed its course to flow eastwards near the Suffolk - Essex border into the southern North Sea. The Thames valley to the north of London was blocked by ice during the Anglian/Elsterian glaciation, causing a series of glacial lakes to form. Overflow of these lakes brought the river into its modern valley through London. It is thought that this valley already existed by the Anglian in the form of a tributary of the north-flowing River Medway, which joined the old Thames valley near Clacton. Also during the Anglian/Elsterian glaciation. British and continental ice masses are thought to have joined in the northern part of the North Sea basin, causing a large lake to form between the east coast of England and the Netherlands. It is widely believed that the overflow from this lake caused the first breach in the Weald-Artois Ridge, bringing about the formation of the Strait of Dover. Prior to the glaciation the Thames, in common with rivers from the continent (including the Rhine and Meuse), flowed into the North Sea Basin. It seems that, after the lake overflow, these rivers together drained southwards into the English Channel. Whether this southern drainage route was adopted during all later periods of low sea level remains to be determined, but it seems certain that this was the case during the last glacial.De nombreuses captures ont modifé le cours de la Tamise et des autres fleuves du bassin de Londres au cours du Quaternaire. L'une d'entre elles au moins est le résultat direct des glaciations. Au Quaternaire inférieur. Ia Tamise coulait au nord de Londres à travers l'East Anglia, vers la côte nord du Norfolk. Au début du Pléistocène moyen, elle avait changé de cours pour se diriger vers l'est, à la frontière entre Essex et Suffolk, vers le sud de la mer du Nord. Au cours du maximum glaciaire de l'Anglien/Elstérien, les glaces ont bloqué la vallée de la Tamise au nord de Londres, provoquant la formation de lacs. La vidange de ces lacs a provoqué le déversement de la rivière vers sa basse vallée actuelle. Celle-ci existait déjà, mais était alors parcourue par un affluent de la Medway qui coulait vers le nord, et rejoignait l'ancienne vallée de la Tamise aux environs de Clacton. Il semble que durant les glaciations de l'Anglien et de l'Elstérien, les calottes glaciaires britannique et continentale étaient coalescentes dans la partie septentrionale du bassin de la mer du Nord. Il en est résulté la formation d'un vaste lac entre les côtes de l'Angleterre orientale, du Danemark et des Pays-Bas. L'écoulement de ce lac s'est probablement fait par la Manche, entre le Weald et le massif de l'Artois, provoquant la formation du Pas de Calais. Avant la glaciation. Ia Tamise confluait avec...

Bayesian phylogeographic inferences reveal contrasting colonization dynamics among European groundwater isopods

“…Our results revive former scenarios suggesting that short-term dispersal windows might have been instrumental in shaping the present-day distribution of groundwater taxa (Magniez 1981). For example, Henry (1976) proposed that P. cavaticus had colonized Great Britain during late glacial maximum when north European rivers including the Rhine, Meuse, Weser and Thames Rivers were connected (Bridgland & Gibbard 1997). A similar scenario implying late glacial dispersal along the Rhône River from Alpine refugia was proposed to explain the occurrence of P. cavaticus in southern France (Henry 1976).…”

“…For example, Henry () proposed that P . cavaticus had colonized Great Britain during late glacial maximum when north European rivers including the Rhine, Meuse, Weser and Thames Rivers were connected (Bridgland & Gibbard ). A similar scenario implying late glacial dispersal along the Rhône River from Alpine refugia was proposed to explain the occurrence of P .…”

Habitat fragmentation and extinction rates within freshwater fish communities: a faunal relaxation approach

“…1). Because of uncertainties about their connection to the Channel River (Antoine et al ., 2003) or the timing of their separation (Bridgland & Gibbard, 1997), rivers that were part of the palaeo‐Rance and the Northern Palaeo‐valley were not considered in this regional study.…”

Reconstructing Quaternary Rhine–Meuse dynamics in the southern North Sea: architecture, seismo‐lithofacies associations and malacological biozonation

“…During the Saalian, onshore Rhine-Meuse channels were diverted from their northern route to the west by the ice sheet. Offshore the diverted channels joined with the Thames to form the Palaeo-Channel river running south-west along the axis of the southern North Sea (Roep et al, 1975;Oele and Schttenhelm, 1979;Laban et al, 1984;Gibbard, 1988Gibbard, , 1995Joon et al, 1990;Laban et al, 1992;Keen, 1995;Laban, 1995;Bridgland and Gibbard, 1997;Gibbard and Lautridou, 2003;Busschers et al, 2005Busschers et al, , 2008Gupta et al, 2007;Bridgland and Westaway, 2008;Passchier et al, 2010;Westaway and Bridgland, 2010). The Saalian Palaeo-Channel river eroded and deepened the pre-existing palaeo-channel(s) in the Dover strait, ultimately leading to a full marine connection with the southern Lusitanian mollusc fauna province during the subsequent interglacials and a southward diversion of the Rhine-Meuse system during the last glaciation.…”

“…During the Pleistocene glacials these nowsubmerged extensions of the Rhine-Meuse system were an intrinsic part of an extensive fluvial drainage network that included the Thames (Fig. 1a; Oele and Schttenhelm, 1979;Cameron et al, 1984a;Laban et al, 1984;Gibbard, 1988Gibbard, , 1995Bridgland, 1994Bridgland, , 2003Bridgland and D'Olier, 1995;Bridgland and Gibbard, 1997;Gibbard and Lautridou, 2003;Busschers et al, 2005Busschers et al, , 2007Busschers et al, , 2008Bridgland, 2010;Westaway and Bridgland, 2010). Despite earlier studies, knowledge regarding the extent, and our understanding of the lithology and sedimentology of the offshore Rhine-Meuse network is fragmentary, due to the complex and expensive nature of offshore data acquisition.…”