Geology of the Netherlands

The geology of the Netherlands and Flanders is clearly divided into two parts:

• The Quaternary sediments at the surface, determine the landscape and geomorphology of the Netherlands and Flanders, the study also falls under the Physical Geography;
• The solid rocks deep underground, which are particularly important for economic reasons, they can be studied by geologists and mining researchers.

One consequence of this situation is that this division of research anywhere in the world so clearly as here.

• 3.1 Vorvariszischer base
• 3.2 carbon
• 3.3 Permian and Triassic
• 3.4 Jurassic and Cretaceous
• 3.5 tertiary

Overview

Flanders and the Netherlands are in the north of the Ardennes, the western part of the Rhenish Slate Mountains. They are made on the surface as well as the a large part of Denmark and northern Germany from unconsolidated, very young ( Quaternary ) sediment.

Due to the proximity of the low-lying part of the European continent, the basin of the North Sea, the Netherlands and Flanders project rarely much higher than 30 meters above the sea beyond. The rivers that now flow into the North Sea, the Rhine worried with his side arms, the Ems and other smaller rivers have Meuse, the Scheldt, for the supply of a large amount of sediment, leading to the formation of a large delta of the Rhine - Meuse delta, has led.

As a result, solid rocks rarely come to the surface. On more than 80 % of the Netherlands occurred sediments days that are less than a million years old. This is similar to the geological situation of those that can be found in many geologically young subsidence areas, and older rocks are almost everywhere in the deeper underground hidden.

Near-surface deposits

Quaternary sediments are mostly called " earths " or " soil types " in the Netherlands. Which sediment in the soil occurs largely determines the current subdivision and land use, and landscape.

Eisrandlagen ( Präglazial and Saaleglazial )

On sections of the major rivers of the Netherlands and in some places in the far east of the country come to the surface sediments that are older than the penultimate Eisvorstoß that Saaleglazial ( between 380000-150000 years before present). In the west and in the middle of the Netherlands this präglazialen gravels and sands only come to the surface when they are highly congested by the blowing action of glaciers in the so-called Eisrandlagen. Examples of large Eisrandlagen are the Utrecht Hills, the Veluwe and the Salland ridge. Along the outer sides of the Eisrandlagen was left behind by the glacier boulder clay.

Cover sand and loess ( Weichselglazial )

In the last section of the Ice Age, the Weichselglazial (about 110,000 before - 11,000 years ago ), a large part of the sea water areas was just as in the previous glacial deposited as ice in the ice sheets, at higher latitudes such as Scandinavia fully covered. In contrast to Saaleglazial the ice sheet did not come to the Netherlands. However, a large part of the North Sea was (which in most places is not deeper than 30 m ) by the lowering of the sea level dry. In the dried-up area, there was the climate of a polar desert where the wind had free rein. In the regions in the south of present-day North Sea was deposed by the wind ( aeolian ) sand, the so-called deck sand. The further south you go, the smaller the grains entrained by the wind, so that the top sand to the south is towards ever finer. Approximately south of the line Roermond- Antwerp the cover sand goes in loess, a soil type, consisting of well-sorted, fine grains.

Aeolian sediments such as sand and loess cover have the property to compensate for the relief of the landscape by gradual coverage of terrain depressions and slope buckling. That's why the cover is sand in the northern Netherlands wedge-shaped against the Eisrandlagen.

Clay deposits, Eisrandlagen and fens ( Holocene )

In the regions along the coast ( provinces of Groningen, Friesland, North Holland, South Holland, Zeeland, West Flanders East Flanders and ) are the surface soil layers mainly of clay deposits. To the west of the Netherlands, the clays are replaced by fens. Both were deposited after the glaciers retreated and sea levels began to rise ( transgression ). This was done in two major cycles:

• In the first cycle after the ice age, the Boreal (before 11,000 to 8,000 years ago ), were formed by the thawing of the permafrost in the ground marsh marshlands. Along the formed by the flowing seawater new coastline itself formed a strip of dunes, behind which lay a swamp. During this period, especially Moore, called in their entirety the base Moor.

• This was followed by a period of rapid sea-level rise and warmer climate. This period is called the Atlantic period (before 8,000 to 6,000 years ago ). The sea washed over a large part of the Netherlands, the swamp made ​​an inland sea dotted with lagoons space, were sold in the tone. These clays are called old blue tone. In many places the base Moor was swept away by wave action, so that it is no longer located anywhere in the underground.

• On the Atlantic period, the less warm period of the Sub-boreal followed (approx. before 6,000 to 3,000 years ago ), in which the sea retreated somewhat. The lagoons grew back together into swamps, where a new peat layer was deposited. These deposits, called Hollandveen, come in some areas in the North and South Holland, and Utrecht in the province to the surface. In many places they were dug to be used as fuel. This lakes were created.

• On the Subboreal the Subatlantic in which the sea level rose again followed. In some places the water broke through the row of dunes formed a lagoon or an inland sea. An example of this is the Flevomeer, which was approximately at the site of the present Flevoland. In the coastal areas behind the dunes clay was deposited again, the so-called young lacustrine clay. Formed on the banks in the same time the higher young dunes.

River clay

River or Auenlehm was deposited throughout the Quaternary where rivers flowed. In cold periods the rivers held more water than in warm periods and were interwoven cycles of ( braided river). In the warm periods like the present Holocene meandering rivers occur. The amount of water of the rivers has been higher during the ice ages.

Over time, the Rhine, IJssel, the Scheldt and the Meuse have their lower courses laid in the Dutch coastal plain several times. That's why can be found in the subsurface at some places river clay, where today no river flows. At the same time remained a network of old ( sandy ) current back in the underground of the river basin. Before Saaleglazial flowed as the Rhine from there to the north, where Arnhem is today, rather than, as now, to the west. By forming the ice stage of the Veluwe, the river has shifted later.

Further south lie the rivers in a " stronger " position in a valley, as the Meuse in Limburg. Here's river clay found only in a strip along the river.

Moor

In the high altitude Eisrandlagen be raised bogs were formed. These cover a large area there; in the rest of the Netherlands, the fen is more widespread. The raised bog is however not limited to Eisrandlagen, it can also form on other higher, less permeable soils, such as in the High Fens.

Rocks deep underground

The rocks in the Dutch, Belgian and North North German underground are comparable to other places in Western Europe in general terms with them. Some of the rocks listed here, and known only from the subsurface are found in the Ardennes on the surface.

Vorvariszischer base

The base is formed by frühpaläozoische rocks which are older than the Variscan orogeny ( to around 390-300 Ma). These are usually located a few kilometers depth, in the south of the Netherlands and Flanders they rise in the so-called Brabant Massif to the surface so that they are open-minded in some valleys Nordbelgiens.

Carbon

Rocks from the Carboniferous come only in a few places in the extreme southeast of Limburg to the surface. You have been deposited at the edges of the Variscan mountain belt in shallow coastal marshes. From the vegetable combinations formed after its death, and the coverage by sand and silt initially lignite and later coal, which was the basis for the mining industry in South Limburg until the 1970s.

Permian and Triassic

In the south of present-day North Sea was a shallow inland sea in the Permian. This was filled in and Permian sandstone with degradation products of the Variscan mountain belt, sandstones and conglomerates of the south. In the south of the Netherlands and in Belgium they are missing altogether. To the north, where the sea was deepest, these layers are thicker. They serve as reservoir rocks in which oil and gas could collect from the underlying Carboniferous.

On these porous rock layers impermeable layers were deposited, so by the retreat of the sea in the Zechstein and Keuper evaporites (mainly salt ) and limestone in the Jura. These rocks have ensured that in many places in the Dutch underground oil and natural gas could not escape and now is commercially viable. The salt from the Zechstein and Keuper has under northern Germany, the North Sea and the Netherlands, where these layers were the most powerful, enormous diapirs ( salt domes ) are formed.

Jurassic and Cretaceous

During the Jurassic and Cretaceous, the mountains were almost completely eroded in the south. Both the Netherlands and Belgium were covered by a shallow sea. Especially at the end of the Cretaceous thick limestone layers were deposited here. These come on the edge of the Ardennes to the surface, for example, in Maastricht, where the limestone is mined in the quarries of ENCI Holding. The well- digested and fossiliferous limestones around Maastricht gave the Maastrichtian, the top step of the Cretaceous, their name. In Limburg, the Cretaceous marl is called, even though it contains little clay and silt. In some places, dry natural gas originated in Cretaceous rocks, which was covered by limestone and is biodegradable.

Sediments from the Tertiary occurred in some places in the south of the great rivers to days. Here, sands and clays alternate. In most places these Tertiary sediments were covered with cover sand or loess. The Tertiary sediments overlie the chalk layers today on the northern edge of the Brabant Massif and fall to the north under the Quartärsedimente Central Niederlands. Show remnants of Tertiary deposits in the High Fens, that the tertiary deposits formerly ranged farther south than today. In the far eastern part of the Netherlands these sediments are in isolated areas in Twente and the Achterhoek also to the surface.