Eaulne

The Eaulne is a river Norman of the Pays of Bray and Petit Caux, long 46 kilometers, flows of the Arques. Within the dendritic network which gives rise to this coastal Fleuve, Eaulne is presented in the form of the Eastern river. Its little urbanized valley, except in its downstream part, profits from an environment preserved and, recently, protected.

Geography

It takes its source with Mortemer, runs parallel to the Béthune, in the north of this one (with approximately 7 kilometers), before joining it with Arch-the-Battles to form, with the Varenne, the Arques. Its green valley follows, during the major part of its course, an anticlinal depression parallel with the Pays of Bray. The substratum is consisted the chalky grounds of the higher Crétacé: Cénomanien and Turonien. Under the plates framing the course of the river, tablecloth of Chalk form an important tank of which the thickness reaches 150 to 170 meters.

To the variation of the strong human concentrations, the river offers favorable conditions of fishing, concealing important colonies of migrating species: Atlantic Salmon, Sea trout, Trout fario, Eel, Lamproie marinades or fluviatile lamprey. The ecological richness of Eaulne is not limited to its piscicultural fauna, because, close to its source, the Marais of Fesques was classified in site Natura 2000 because of its interest of very first order. This zone, bathed by the river, consisted of wet meadows and alder plantations, shelters 91 species of birds of which the sedge warbler and the Tawny owl, 21 of mammals, 2 of reptiles and 4 of Amphibians, but also 72 different plants among which 3 are remarkable: the common Ophioglosse, the Benoite of the brooks and the neglected dactylorhize.

Eaulne sprinkles Holy-Beuve-in-River, Saint-Germain-on-Eaulne, Londinières, Douvrend, Envermeu, Bellengreville, Ancourt, Martin-Church, Arch-the-Battles.

Hydrology

The Area catchment of Eaulne. is not very wide (318 km ²) because of the configuration of the physical environment and thus of the weakness of the tributary network, the Bailly-nozzle which joined Eaulne out of Right Bank with Envermeu is its only notable affluent.

With the discharge system of the river, flow, recorded with the hydrological Station of Martin-Church, reached on average 3,3 m ³ /s).

The valley of Eaulne

Fast Cours d' water, Eaulne was largely used formerly like energy source; many mills marked out it (5 in the only village of Ancourt). Located near forest territories (of upstream downstream: low Forest of Have, Forest of Hellet, Forêt of Arch), the valley saw developing an industry of wood (sawmills), but located apart from the main roads of communication, its manufacturing activities remained modest (contrary to the plate of close Aliermont).

The valley of Eaulne, like that of the close Béthune, carries the mark of a particularly important franque presence. Arrived in the area after the Battle of Soissons (486), the Francs were quickly integrated into the Gallo-Roman populations. Many vestiges Mérovingiens were discovered at the time of excavations carried out since the 19th century, primarily of the necropoles with Lucy, Londinières, Douvrend and especially Envermeu, the principal locality crossed by the river, where more than 800 burials were put at the day. But of other architectural testimonys return to older periods. Menhirs had been set up, by pre-Celtic populations, with Wanchy-Capval; transformed into milliary columns by the Romains which were established in the valley building the way there connecting Beauvais to Dieppe, they were cut in the shape of cross by the first Christians. More close to our time, the period Norman left the trace of many mounds castrales (with Wanchy-Capval, for example) and of fortifications in masonry like the castle of Bridge-Trancart with Ancourt.

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