The Carrière des Nerviens Regional Nature Reserve (in French Réserve naturelle régionale de la carrière des Nerviens) is a protected area in the Nord-Pas-de-Calais region of northern France. It was established on 25 May 2009 to protect a site containing rare plants and covers just over . It is located in the municipalities of Bavay and Saint-Waast in the Nord department.
The reserve was created to protect fifteen plants of regional interest and three plant communities listed in the Habitats Directive. Its flora are linked to calcium present in marl. It is located in a transition zone between the oceanic and semi-continental climates and that gives increased biodiversity, with typical species of the atlantic areas and others more continental. The reserve also plays a role in a wildlife corridor.
The site consists of an old quarry of sandstone dated to the Famennian stage in the Late Devonian epoch. It was backfilled in the 1970s with marl. The new soil was re-colonized by pioneer species, which coexist alongside an established afforestation, forming a mosaic of habitats.
CPIE Bocage de l'Avesnois, a non-governmental organization, is the owner and operator of the reserve. The main objective is to maintain the current diversity. To this end, regular management mainly struggles against the afforestation and against invasive species, such as Japanese knot weed. The secondary objectives are environmental education, heritage interpretation, improvement of knowledge fauna and flora, and environmental monitoring.
Geography
Location
The Carrière des Nerviens Regional Nature Reserve is located in the Arrondissement of Avesnes-sur-Helpe between the cities of Valenciennes and Maubeuge, in the Nord department, Nord-Pas-de-Calais region. It is west of downtown Bavay and south-east of Saint-Waast.
The reserve is triangular in shape. It is bordered to the south by the 942 main road, north-east by an unused railtrack, and to the west by a small path known as . It covers .The Carrière des Nerviens's site is . But only the property of the CPIE Bocage de l'Avesnois is classified of the regional nature reserve; the parcels belonging to other owners were not classified. CPIE Bocage de l'Avesnois owns a parcel of land on the other side of the railtrack. Though not yet included in the reserve, it is expected to be added when the current agreement is renewed.
Relief The reserve is located in the valley of the stream , with an elevation of between . It has an overall north-south gradient of . A mound of accumulated debris, which rises to about above the path , is located north-west of the site. After quarrying operations ceased, the quarry was filled mainly with the marl of the Bellignies quarry. The area has since been completely recolonized by vegetation through ecological succession.
Hydrology The reserve is located in the valley of the , a tributary of the Hogneau, and is part of the greater drainage basin of the Scheldt. The reserve is not in direct contact with the river. It is supplied with water only by precipitation, which is retained by the natural properties of marl.
Climate The reserve's nearest weather station is at Cambrai, about 42 kilometres away, inland, to the southeast. However, the nature reserve is affected by the nearby presence of the Ardennes Mountains, which gives a continental influence to the climate.
The regular precipitation and the absence of drought, as well as the predominance of south-southwest winds and rain vectors, show the influence of oceanic climate. However, some significant rainfall variability between seasons, the moderate temperature range, and the high proportion (69.8 percent) of low winds (less than ) compared to strong winds (3.2 percent over ) winds are typical of a continental influence. This combination is atypical of an altered oceanic climate, a transition zone between the oceanic and semi-continental climates, characterized by mild winters and cool summers.
In the reserve, this climatic transition leads to increased biodiversity. For example, common bluebell (Hyacinthoides non-scripta) is a typical species of the Atlantic areas, while the common butterbur (Petasites hybridus) is more continental.
History
Quarry The site is a former quarry, used for its sandstone deposits as early as the late nineteenth century. by the Chevallier & Cie company, which employed about 70 workers, including 25 miners. In 1909, the annual production was of macadam, of ballast and of cobblestones.
Boreholes were drilled manually. Stone blocks were divided using a mass and a steel heavy hammer (up to ) called . Stones obtained were then classified by eye into stone for cobble and rubble for macadam. The first were : asperities were removed by to form regular cobblestones. They were then sorted by size. The rubble was crushed in a jaw crusher. Debris were mechanically separated according to their size. Each particle has a particular use. Macadam, made of stones between , was used for the construction and maintenance of roads. Ballast is a gravel used for concrete. Shot from was used for the surface of concrete or paths in parks and gardens. The fine dust, from , was used for concrete paver blocks, concrete pipes, etc.
Quarrying ceased in the early 1960s (1962–1965), when the stones extracted were no longer of sufficient quality. Between 1971 and 1978, the quarry was gradually filled with marl from the Bellignies quarry. Since then, the site has been completely recolonized by vegetation through ecological succession, forming tree, shrub and herb layers.
Reserve
In 2001, the site was brought to the attention of the CPIE Bocage de l'Avesnois, pointing out the biodiversity of the new plant life. The association performed the first inventories. In the meantime, she contacted the five owners to consider a land management proposal. The commune of Bavay, the Bellignies quarry (SECAB) and a third owner sold her the property in 2003. The CPIE Bocage de l'Avesnois became the owner / operator of 85 percent of the site. The association implemented the first environmental resources management actions at the site and developed its first environmental management schemeIn France, an environmental management scheme is defined by the (article R332-43). A scientific council must validate it to obtain or maintain the accreditation. In 2009, the association obtained the agreement establishing the regional nature reserve at the site for a period of 20 years.
The name of the reserve recalls the former industrial activity (Carrière: quarry) and the Gallo-Roman history of Bavay, the capital city of the ancient Nervii tribe.
In 2015, another owner give the management of his parcel.
Geology The Paleozoic folded outcrops of the Bavay-Saint-Waast area are the bedrock of the eastern flank of the Mélantois' anticline, where the transgressive Cretaceous (Turonian and Cenomanian chalk) thins, and may eventually disappear by erosion. Strata of Hercynian basement, raised in the East by an important structural horst-type accident, then appear locally. In these Paleozoic strata, the Devonian presents as a sandstone base of the Lower Famennian, where the levels were quarriedThese quarried rocks are no longer visible on the site, as they were fully covered by embankments.
Formations
Quarried level The stone that was quarried is arkoseSome geologists also call those sandstones psammite of the Famennian stage. Approximately 360 million years ago, the thrust of forming Gondwana plates raised the seabed. Meanwhile, an ice age occurred in regions near the poles. Marine regression allowed sedimentation of detrital sand and clays which left large shoals of hard sandstone with ripple marks, alternating with levels more or less shaley according to their clay's content.
At the base of the deposit, these sandstones are reddish brown, very micaceous and shaley, sometimes containing calcareous nodules, ferruginous concretions and vegetable wax; above, they are gray and quartziferous. This is the Aye formation, including spiriferida like Cyrtospirifer verneuili, Rhynchonellida as Rhynchonella pugnus and R. boloniensis, some Orthoceras, Orthis striatula or Atrypa reticularis Well-preserved feldspar and mica probably come from wind erosion under a semi-arid climate of mountains present in the Netherlands today and extending to Düsseldorf.
Lower level
Under the Famennian, the Frasnian consists, from top to bottom, of nodular gray shale, and mica rich in fossils such as Cyrtospirifer verneuili, Spirigera concentrica, Atrypa reticularis, Orthis striatula, Productus subaculeatus, and Acervularia pentagona. Below this are gray limestone-built beds, rich in corals such as Phacellophyllum caespitosum, Thamnopora boloniensis, alternating with black shale and nodular limestone containing Cyrtospirifer verneuilli and Phacellophyllum caespitosum. These beds issue from siltation of the biostromes present in the Frasnian epoch, 370 million years ago.
Upper levels Those Famennian strata represent the top of the Paleozoic series pleated with north dipping. Above, the transgressive Upper Cretaceous overlies horizontally with unconformity. It includes from the bottom to the top a paleozoic boulder conglomerate mixed with a sandy and glauconitic marl matrix, coarse clayey and glauconitic sands, containing Chlamys asper, Ostrea diluviana, Praeactinocamax plenus and finally marl with Terebratulina gracilis. These strata belong to the Cenomanian-Turonian and were deposited between 90 and 100 million years ago, during a transgressive phase.
Fifty million years ago, during the Ypresian age, locally called Landenian, forms of marl of the Porquerie are found. It comes from the alteration of Cretaceous rocks and takes the form of a brown or greenish plastic clay without fossils. The flints normally present at the base of the deposit have not been reported by .
This stratum is covered with silt composed of clay, sand and flints and Roman pottery pieces, of the late Neogene age. Its origin can be attributed to the alteration of the underlying rocks and wind erosion.
Nature of the embankments
The stones used to backfill the quarry are those which underlie the Givetian limestone extracted in the Bellignies quarry. There is , a coarse shelly limestone, deep gray, yellowish when it outcrops, detrital ferruginous dated to the Lower Cenomanian epoch, a hundred million years ago. There is clay and very glauconitic marl of the Upper Cenomanian stage, enriched by a pebble conglomerate paléozoïc stones. These rocks contain Praeactinocamax plenus, Chlamys asper, Ostrea diluviana and radiated fossils: Janira quadricostata, Cyprina ligeriensis, Arca mailleana. There is also bluish marl of the Turonian.
Ecology
Plant communities
The site is characterized by a mosaic of 17 plant communities regrouped into three main types of ecological units: grassy open areas, shrubby areas and wooded areas. Of these, three are listed in the Habitats Directive. The calcareous rocky slopes with chasmophytic vegetation Cystopterido fragilis-Asplenietum scolopendrii are considered as exceptional, with a degree of uncertainty in the Nord-Pas-de-Calais region. Hydrophilous tall herb fringe community with Petasites hybridus, at the limit of its range, is also exceptional. The herbaceous fringe with red campion (Silene dioica) et wood forget-me-not (Myosotis sylvatica) (Sileno dioicae - Myosotidetum sylvaticae) is very rare in the Nord-Pas-de-Calais. The wood-fringe Lathyro sylvestris – Astragaletum glycyphylli is also regionally interesting.
Flora
Vascular plants The reserve has 171 plant species, and 15 of them have heritage interest.