The Seine River from Ile-De-France to Normandy: Geomorphological 3 and Cultural Landscapes of a Large Meandering Valley
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The Seine River from Ile-de-France to Normandy: Geomorphological 3 and Cultural Landscapes of a Large Meandering Valley Jean-Pierre Peulvast , François Bétard , and Christian Giusti Abstract Rich in historical and cultural heritages, the stretch of the Seine valley that links Île-de- France to Normandy, between Mantes-la-Jolie and the Eure and Andelle confl uence zone, belongs to one of the major sets of entrenched meanders known in the world. The valley presents steep hillsides punctuated by white chalk pinnacles alternating with deep funnels, contributing to the picturesque landscape of the valley segment. The geomorphic history of the Seine valley is inseparable of the Quaternary bioclimatic history, with its alternating glacial-interglacial and stadial-interstadial periods. All along the Pleistocene, periglacial processes interacted with fl uvial erosion, leading to the formation, deepening, enlargement, and migration of the large meanders. The resulting, present-day geomorphological land- scapes are enriched by many cultural treasures. Its emblematic sites are the medieval castles of La Roche-Guyon and Les Andelys (Château-Gaillard) which were built on rocky prom- ontories on the concave sides of two large meanders. The mid-Seine valley is also known as a high place of the impressionism, the founder and master of which, Claude Monet, settled here for the second half of his life and created the wonderful gardens of Giverny on the lower Epte River. He and many other impressionist and postimpressionist painters, sensitive to a certain harmony of the local landforms, magnifi ed and immortalized the surrounding landscapes. Keywords Meanders • Chalk erosion • Periglacial features • Impressionism • Castles 3.1 Introduction Among the regions of France where remarkable geomorpho- logical landscapes also represent invaluable historical and cultural heritages, the stretch of the Seine valley that links Île-de-France to Normandy, between Mantes-la-Jolie and the J.-P. Peulvast (*) Eure and Andelle confl uence zone, is one of the most present Geomorphology , University of Paris-Sorbonne , Paris , France in the collective memory. Due to moderate heights, it does e-mail: [email protected] not display the most spectacular landforms in any specifi c F. Bétard geomorphic type, although it belongs to one of the major sets Physical Geography , Paris-Diderot University , Paris , France of entrenched meanders known in the world. It rather owes e-mail: [email protected] its fame to events and constructions linked to its position on C. Giusti the most active way linking Paris to the sea and on the his- Physical Geography and Environmental Sciences , University of Paris-Sorbonne , Paris , France torical border of Normandy, as well as to the numerous liter- e-mail: [email protected] ary and pictorial representations of its landscapes. The valley M. Fort and M.-F. André (eds.), Landscapes and Landforms of France, World Geomorphological Landscapes, 17 DOI 10.1007/978-94-007-7022-5_3, © Springer Science+Business Media Dordrecht 2014 18 J.-P. Peulvast et al. Fig. 3.1 Vétheuil (in the background, right side ) and the concave side the Campanian chalk (pinnacles), whereas the upper half corresponds of the Moisson meander of the Seine valley, from Haute-Isle (Photo J.P. to Cenozoic layers. A winter fl ood underlines some lateral channels Peulvast, January 1982). Only the lower half of the slope is shaped into outside the main one (island on the right side ) presents steep sides punctuated by white chalk pinnacles and right side, marks the entrance of the valley in Normandy pierced by caves and troglodyte dwellings (Fig. 3.1 ). Its (Fig. 3.2a ). Upstream, the Seine River separates the Vexin emblematic sites are the castles of La Roche-Guyon and Les Français (north), from the Mantois region (south); both units Andelys (Château-Gaillard), ancient lookouts on the Seine belong to the same plateau area. valley, the latter having been harshly disputed in the thir- Whereas the Seine River fl ows to NW, from 19 to 8 m teenth century between the Duke of Normandy and King of a.s.l. downstream of Les Andelys, this plateau largely dedi- England, Richard the Lionheart, followed by John Lackland, cated to farming gently slopes to southeast, from 150 to and the King of France, Philippe August. But the mid-Seine 160 m in the tabular Vexin Normand to 120–140 m around valley is also known as a high place of the impressionism, Mantes-la-Jolie. Therefore, increasing heights (up to 140 m) the founder and master of which, Claude Monet, settled here characterize the valley sides. More and more spectacular for the second half of his life and created the wonderful downstream, they form outstanding historic and touristic gardens of Giverny on the lower Epte River. He and many sites (Château-Gaillard, Côte-des-Deux-Amants ; Fig. 3.3a, b ). other impressionist and postimpressionist painters magnifi ed In the Vexin Français, north of Mantes-la-Jolie, narrow and immortalized the surrounding landscapes. Beyond the WNW-ESE alignments of wooded buttes overlook the plateau quality of the light, all these artists were sensitive to a certain close to the valley, reaching 206 m a.s.l. near Vétheuil harmony of the local landforms. A more scientifi c approach (Fig. 3.2a ). The valley fl oor is generally wide (1–2 km), helps in understanding the layout of these landforms and although it locally narrows to 600 m, between Giverny and discovering a rich geomorphological heritage which contrib- Vernon. However, the presence of a few confl uence zones uted to justify the preservation of part of them in the “Parc and, above all, the meandering outlines of the main valley naturel régional du Vexin Français.” explain considerable variations in width as well as strong asymmetries in the valley sides. Left-side tributaries remain scarce and short down to the 3.2 Geographical Setting wide confl uence plain of the Eure River (Fig. 3.2a ). Downstream of the narrow Vaucouleurs valley, which cuts Sheltering two important cities, Mantes-la-Jolie and Vernon, through the low fl uvial terrace forming the urban site of the studied segment of the Seine valley crosses the border Mantes-la-Jolie, a few deep and mostly dry valleys only between Île-de-France and Normandy 50–100 km down- incise the rim of the otherwise weakly dissected plateau. On stream from Paris. It includes two sets of large meanders the right side, short tributaries also dissect the rims of the separated by a 20 km long rectilinear segment, from Vernon Vexin Français and Vexin Normand. Only some of them are to Gaillon. The confl uence zone of the Epte River, on the drained by permanent creeks, in their downstream reaches. 3 The Seine River from Ile-de-France to Normandy: Geomorphological and Cultural Landscapes of a Large Meandering Valley 19 Fig. 3.2 The Seine valley and its surroundings between Mantes-la-Jolie and former sand pits. (b ) The Gaillon-Les Andelys meander. Note the and the Eure-Andelle confl uence zone. ( a ) 3D representation, from chalk pinnacles around Les Andelys (the small city on the right side ), SRTM DEM (F. Bétard). Note the importance of large enclosed depres- the large sand pits in the alluvial plain and the Port-Mort dam and lock. sions on the valley fl oor, mainly downstream of Mantes-la-Jolie: active Red strip : the abandoned meander of Daubeuf (Photo J.P. Peulvast) 20 J.-P. Peulvast et al. Fig. 3.3 The concave side of the Les Andelys and Poses meanders at les Andelys, from Château-Gaillard ( a ) and at Amfreville-sous-les-Monts, from the Côte-des-Deux-Amants ( b ) (Photos J.P. Peulvast). Inherited periglacial landforms (Richter slopes, chalk pinnacles) overlooking a narrow “modern” alluvial plain 3 The Seine River from Ile-de-France to Normandy: Geomorphological and Cultural Landscapes of a Large Meandering Valley 21 However, two bigger rivers coming from the humid Pays de resistance allows the formation and preservation of steep Bray, to the north, form wider confl uence zones. The lower cliffs along rivers and shores. Epte valley, a well-calibrated fl uvial trough, only widens at The Cenozoic sediments that overlay the Late Cretaceous Giverny, separated from the Seine valley on its last 5 km by chalk are only represented to the southeast (Vexin Français) an elongated plateau strip reduced to a low crest near La and to the south, between the Seine and Eure valleys. Roche-Guyon. On the contrary, the lower Andelle valley, Paleocene sediments are absent, except in tiny depressions also turning from SSW to WSW, directly opens on the where reefal and peri-reefal limestones are preserved along 3–4 km wide Seine-Eure confl uence zone at Pîtres, below a paleo-fault scarps (Vigny). In the Eocene and Oligocene, the protruding spur named Côte-des-Deux-Amants. sea invaded periodically the center of the Paris Basin from The sinuous parts of the valley, with wavelengths of the English Channel, along a low Seine corridor limited to 4–5 km, classically display low convex and asymmetric the north by the NW-SE Bray antiform. After a lacustrine lobes gently sloping to the downstream side, opposite to phase in the Ypresian (Sparnacian clays), the last important high, abrupt, and partly rocky slopes sharply cut into the con- layer of Lutetian marine limestone (“calcaire grossier”) was cave sides, either directly into the plateau or into the upstream deposited in a large bay. It presently forms structural sur- side of the inner lobes. The most of these convex lobes are faces in the Vexin Français and south of the Seine River. elongated perpendicularly to the general trend of the valley, Continued by lacustrine and lagoonal sand, marl, and lime- over 6–7 km.