TERRITORY: MORPHOLOGY
With the exception of the extreme southern appendage of Limburg, where the last hilly reaches of the Ardennes rise, structurally the territory of the Netherlands, recently formed, constitutes a strip of the lowlands that extend to the margins of the ancient massifs of central Europe. In particular, the formation of the inland plain of the Netherlands must be attributed to the action of the rivers (especially the Rhine) which, flowing into the sea, have deposited large alluvial masses over time. The territory, located for approx. 2/5 below sea level, it rarely exceeds 100 m of altitude and is protected by dunes and dams: already in Roman times Batavi and Frisoni had erected embankments to defend the sea, while the first organic systems of dams date back to the 8th and 9th centuries. The geological structure is quite simple. Except for small strips of Mesozoic land (which in turn rest on layers of the Carboniferous, i.e. Paleozoic) present in the southern regions of the Netherlands, the most ancient soils, of both marine and continental formation, date from the Cenozoic and constitute, so to speak, the base of the country. However, they emerge only in limited southern and eastern areas, as significant alluvial contributions of the Meuse, Scheldt and Rhine overlapped them in the Neozoic. At the beginning of the Neozoic (Pleistocene), the Scandinavian glaciers covered the region, forcing the courses of water to bend towards W and superimposing the bottom moraines on the clayey layers, in the depressions of which the peat bogs were subsequently formed. At the end of the ice age, following a slow rise in sea level ( Flandrian transgression) the region was again invaded by the waters, from which only the highest river terraces, the moraine hills and, towards the West, the dunes formed by sea currents and wind emerged. A slight regression, which occurred between the second millennium BC. C. and the historical period, favored the formation of long dune strings and therefore of a second series of peat bogs on the territory of the Netherlands which extended up to the line marked today by the Frisian islands. However, in the sec. XII-XIV, violent storm surges broke the cordon of dunes and the sea invaded the country again, forming large gulfs along the southwestern coast and, further north, in place of the marshy area of Lake Flevo, the vast inlet of the Zuiderzee (see IJsselmeer). It was from these gulfs that the reconquest of the territory began by man who over time has subtracted land from rivers, lakes, peat deposits and even the sea. The current morphology of the country, largely determined by the work of human transformation (the territory can be defined as the most “artificial” in the world), is overall unitary. However, there are differences between the innermost part of the country, occupied by fluvio-glacial terraces formed by the ancient accumulations of debris of the Meuse, the Scheldt and the Rhine, where today the natural marshes have given way to crops, and the western section, largely below sea level, where an amphibious landscape consisting of Zeeland extends, from the arms of the Meuse and the Rhine, from marshes (Biesbosch) and from the polders (Holland and Friesland): this is the area protected by the bulwark of the dunes, torn apart both in the Middle Ages and in modern times (disastrous dam breaks occurred in 1953). Without the dams that channel the river beds or oppose the sea, almost a third of this territory would be submerged again. Finally, a separate region is Dutch Limburg, the extreme edge of the Cretaceous plateau of middle Belgium, where pebble terraces and wide clayey valleys extend which testify to the erosion and deposit phases linked to glaciation and sea level variations and which they turn to the NW, to disappear under the current delta of the Meuse and the Rhine.
TERRITORY: HYDROGRAPHY
According to itypeusa, the territory of the Netherlands includes the lower reaches and mouths of some of the major European rivers. Contained in several points by mighty banks, most of these rivers have large stretches of hanging course and do not receive any significant tributaries. Dutch hydrography has been so modified by man that it is very difficult to reconstruct its original conditions. The Meuse is the river that belongs to the Netherlands for the most part (239 km). After marking the border with Belgium, it enters Dutch territory and maintains its course almost parallel to that of the Rhine, indeed, until the beginning of the twentieth century it went to throw itself into the branch of the Rhine which takes the name of Waal. However, the different regimes of the rivers created drawbacks in the outflow, so it was decided to partly give an outlet to the Meuse: currently, thanks to a canalization system, one branch joins the Waal, another flows into the Hollands Diep estuary . As soon as it enters Dutch territory, the Rhine divides into several branches: the southern one which, with the name of Waal, runs parallel to the Meuse; the northern one that flows into the North Sea near Leiden; the lower Rhine which turns to the W and with the name of Lek flows into the North Sea; the IJssel which heads N and flows into the IJsselmeer. Among other rivers, the Scheldt, of which the Dutch territory includes only the mouth, the Vecht (Vechte in Germany) and the Hunse. In addition to these waterways, the Netherlands has a very large number of canals, which are used for reclamation, drainage and navigation.
