Weald-Artois Anticline

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Weald-Artois Anticline

The Weald–Artois anticline is a large anticline

Anticline

In structural geology, an anticline is a Fold that is Convex set up and has its oldest Stratum at its core. The term is not to be confused with antiform, which is a purely descriptive term for any fold that is convex up....
, a geological structure running between the regions of the Weald

Weald

The Weald is the name given to a physiographic area in south-east England situated between the parallel chalk escarpments of the North Downs and the South Downs....
in southern England

England

Artois

Artois is a former provinces of France of northern France. Its territory has an area of around 4000 km? and a population of about one million....
in northeastern France

France

France , officially the French Republic , is a country whose Metropolitan France is located in Western Europe and that also comprises various Overseas departments and territories of France....
. The fold formed during the Alpine orogeny

Alpine orogeny

The Alpine orogeny is an orogeny phase in the Tertiary that formed the mountain ranges of the Alpide belt. These mountains include the Atlas Mountains, the Pyrenees, the Alps, the Dinaric Alps, the Pindus, the Carpathians, the Balkan Mountains, the Taurus Mountains, the Caucasus Mountains, the Alborz, the Zagros Mountains, the Hindu Kush, t...
, from the late Oligocene

Oligocene

The Oligocene is a geologic epoch of the Paleogene Geologic Timescale and extends from about 33.9 million to 23 million years before the present....
to middle Miocene

Miocene

The Miocene is a Geologic time scale of the Neogene period and extends from about 23.03 to 5.33 million years before the present. As with other older geologic periods, the rock beds that define the start and end are well identified but the exact dates of the start and end of the period are uncertain....
. The folding

Fold (geology)

The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary Stratum, are bent or curved as a result of plastic deformation....
resulted in uplift

Tectonic uplift

Tectonic uplift is a geology process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation....
of about 180 metres, though concurrent erosion

Erosion

For morphological image processing operations, see Erosion 'For use of in dermatopathology, see Erosion Erosion is the removal of solids in the natural environment....
may have substantially reduced the actual height of the resulting chalk

Chalk

Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. It forms under relatively deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
ridges.

As is the case with all anticlines, older rock strata are found in the core of the structure.

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The Weald–Artois anticline is a large anticline

Anticline

Weald

The Weald is the name given to a physiographic area in south-east England situated between the parallel chalk escarpments of the North Downs and the South Downs....
in southern England

England

Artois

Artois is a former provinces of France of northern France. Its territory has an area of around 4000 km? and a population of about one million....
in northeastern France

France

Alpine orogeny

Oligocene

The Oligocene is a geologic epoch of the Paleogene Geologic Timescale and extends from about 33.9 million to 23 million years before the present....
to middle Miocene

Miocene

Fold (geology)

Tectonic uplift

Erosion

Chalk

Kent

Kent is a Counties of England in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the River Thames estuary....
, Sussex

Sussex

Sussex , from the Old English Su?seaxe , is a Historic counties of England in South East England England corresponding roughly in area to the ancient Kingdom of Sussex....
and Surrey

Surrey

Surrey is a counties of England in the South East England of England and is one of the Home Counties. The county borders Greater London, Kent, East Sussex, West Sussex, Hampshire, and Berkshire....
has been greatly eroded, with the presumed chalk surface removed to expose older, Lower Cretaceous rocks (Wealden Group) and a small area of Upper Jurassic Purbeck Beds. On the French side of the English Channel more Upper Jurassic rocks crop out in a small area around Boulogne-sur-Mer

Boulogne-sur-Mer

Boulogne-sur-Mer is a city in northern France. It is a Subprefectures in France of the Departments of France of Pas-de-Calais.The population of the city was 44,859 in the 1999 census, whereas that of the whole metropolitan area was 135,116....
and Desvres

Desvres

Desvres is a Communes of France in the Pas-de-Calais Departments of France in northern France. It is a market town, known for its pottery.In 1999 its population was 5,260 inhabitants for the commune and 14,164 inhabitants for the canton....
, where mainly Upper Jurassic deposits are exposed. At the flanks of the anticline outcrops of the (younger) Upper Cretaceous Chalk occur. The chalk survives as a rim of inward-facing escarpment

Escarpment

In geomorphology, an escarpment is a transition zone between different physiogeographic provinces that involves a sharp, steep elevation differential, characterized by a cliff or steep slope....
s, forming the North Downs

North Downs

The North Downs are a ridge of chalk hills in south east England that stretch for 120 miles from Farnham in Surrey to the White Cliffs of Dover in Kent....
and South Downs

South Downs

The South Downs is one of the four areas of Southern England Chalk Formation downland in southern England. They extend from the eastern side of Hampshire through Sussex, culminating in the cliffs at Beachy Head....
. The Chalk forms characteristic white cliff

Cliff

In geography and geology, a cliff is a significant vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them....
s on both sides of the English Channel, an example are the white cliffs of Dover

White cliffs of Dover

The white cliffs of Dover are cliffs which form part of the Great Britain coastline facing the Strait of Dover and France. The cliffs are part of the North Downs formation....
.

Formation of the English Channel

The English Channel itself is geologically speaking a very young feature, with no relation to the Weald-Artois Anticline. The anticline continues uninterrupted in the subsurface of the Channel.

During the Pleistocene

Pleistocene

The Pleistocene is the epoch from 1.8 million to 10,000 years Before Present covering the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
an ice sheet blocked the flow of rivers including the Thames and Rhine

Rhine

File:Swiss Grand Canyon.jpgThe Rhine is one of the longest and most important rivers in Europe, at , with an average discharge of more than ....
to the North Sea

North Sea

The North Sea is a marginal sea, epeiric sea on the European continental shelf. The Dover Strait and the English Channel in the south and the Norwegian Sea in the north connect it to the Atlantic Ocean....
, resulting in a large proglacial lake

Proglacial lake

In geology, a proglacial lake is a lake formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier, or one formed by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice....
to the northeast of the ridge. To the southwest, low-lying land connected the island that is now Great Britain

Great Britain

Great Britain is an island lying to the northwest of Continental Europe. It is the List of islands by area, and the largest in Europe. With a population of 58.9 million people it is List of islands by population....
to continental Europe

Europe

Europe is, conventionally, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural , the Caspian Sea, and by the Caucasus Mountains to the southeast....
. Overtopping of this ridge at two separate times resulted in the severing of this peninsular connection. The first glacial lake outburst flood

Glacial lake outburst flood

A glacial lake outburst flood can occur when a lake contained by a glacier or a terminal moraine dam fails. This can happen due to erosion, a buildup of water pressure, an avalanche of rock or heavy snow, an earthquake or cryoseism, volcanic eruptions under the ice, or if a large enough portion of a glacier breaks off and massively displa...
occurred approximately 425,000 years ago, resulting in a waterfall of up to a million cubic meters per second that gouged out the Straits of Dover and flooded the low-lying land. The second, which may have been larger than the first, occurred approximately 225,000 years ago and finally severed the slender peninsula.

During the most recent, Devensian glacial period, lowering of sea levels joined the British Isles once more to the continental mainland of Europe

Europe