<P> By the end of the Carboniferous period the various continents of the Earth had fused to form the super-continent of Pangaea . Britain was located in the interior of Pangea where it was subject to a hot arid desert climate with frequent flash floods leaving deposits that formed beds of red sedimentary rock . </P> <P> As Pangaea drifted during the Triassic, Great Britain moved away from the equator until it was between 20 ° and 30 ° north . The remnants of the Variscan uplands in France to the south were eroded down, resulting in layers of the New Red Sandstone being deposited across central England . </P> <P> Pangaea began to break up at the start of the Jurassic period . Sea levels rose and Britain drifted on the Eurasian Plate to between 31 ° and 40 ° north . Much Britain was under water again, and sedimentary rocks were deposited and can now be found underlying much of England from the Cleveland Hills of Yorkshire to the Jurassic Coast in Dorset . These include sandstones, greensands, oolitic limestone of the Cotswold Hills, corallian limestone of the Vale of White Horse and the Isle of Portland . The burial of algae and bacteria below the mud of the sea floor during this time resulted in the formation of North Sea oil and natural gas </P> <P> The modern continents having formed, the Cretaceous saw the formation of the Atlantic Ocean, gradually separating northern Scotland from North America . The land underwent a series of uplifts to form a fertile plain . After 20 million years or so, the seas started to flood the land again until much of Britain was again below the sea, though sea levels frequently changed . Chalk and flints were deposited over much of Great Britain, now notably exposed at the White Cliffs of Dover and the Seven Sisters, and also forming Salisbury Plain . </P>

Describe where the upland areas of the uk are