| London-brabant Island |
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Information AboutLondon-brabant Island |
| CATEGORIES ABOUT LONDON-BRABANT ISLAND | |
| geology of england | |
| structural geology | |
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FORMATION To state events very simply, the rocks of which it is formed are mainly of the Precambrian , Cambrian , Ordovician and Silurian but the anticlinal folding came with the Caledonian Orogeny at the end of the Silurian and in the early Devonian , when the continent was Drifting through the southern Latitude s. As it passed through the dry latitudes represented today by the Namib Desert 1 , it was Eroded and the Soil s became Laterite represented by the Old Red Sandstone which shows its presence in the red soils of Devonshire . The Strata , particularly of the Precambrian are complex. They are also poorly understood because they are beyond the reach of most Borehole s. THE CARBONIFEROUS The period from which the island has exercised most influence on modern Europe was the Carboniferous . As the continent was drifting past the Equator , on the island's shores, there grew a rich Tropical Forest Swamp . On the island's southern shore, it left the Dinantian , Namurian and Westphalian Coal Field s of France and Belgium . To its north-west, it left those of Leicestershire and Nottinghamshire . These extend further east but at ever greater depth. At the modern east Yorkshire and north Lincolnshire coast for example, their upper surface is at about 2km depth. On the north Norfolk coast, the line of the Carboniferous shore roughly coincides with the modern one. 2 THE PERMIAN AND TRIASSIC As the continent drifted northwards, away from the Equator, through the latitudes represented today by the Sahara Desert , the erosion was renewed. This time, the lateritic soils are represented by the New Red Sandstone and the red soils of Leicestershire and Rutland . The early Permian was the time of the height of the Variscan earth movements as the crust to the south was crushed against the island. The great disturbances seen at the surface in Brittany , the Ardennes and the Rhineland also lie below the Paris Basin. They fade out in the gentler Anticline of the downs and Weald of southern England which overlies the edge of the island. The axis of this anticline is normally called the northern Variscan front (''Le front nord varisque''). However, the chalk of the downs is Upper Cretaceous, so the process continued well after the Permian. The point in the present context is that the stability of the island contrasts with the relatively unstable crust to its south. RHAETIC TRANSGRESSION In the early Jurassic , the Rhaetic sea flooded much of the Permian plain. On the margin of the London-Brabant Island, the Estuarine conditions which left the Lower Estuarine Series prevailed for a while before the sea rose so as to deposit the Lincolnshire Limestone s before falling again so that the Upper Estuarine Series was left. Again the sea rose to deposit the Blisworth Limestone , the Blisworth Clay and the Upper Jurassic clays. The same general pattern occurred in France leaving the Paris Basin flooded from Anjou to Luxembourg. CRETACEOUS By the Cretaceous the island had sunk much further in relation to the sea level. Before the end of the period, the British end was buried in Upper Cretaceous chalk. This happened because the Pacific Ocean bed swelled up causing the world’s seas to rise but also, the process released much carbon dioxide. That caused global warming, melted the ice caps and was slowly converted to calcium carbonate which was precipitated in the water. MODERN EXISTENCE It is now best viewed as a block of dense crust floating deeply sunk into the mantle and overlain with less dense superficial rocks. It depresses the Moho to depths greater than 40 kilometres as against a figure at the top of the Continental Shelf of about thirty and less than fifteen below Oceanic Depths . 3 SEE ALSO REFERENCES
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