To the south, the Alpine Orogeny created vast mountain ranges across central Europe, including the Alps and the Pyrenees. However, it was also responsible for the shaping of the London Basin syncline and the Weald anticline, leading to the development of the North Downs, the South Downs and the Chiltern Hills. The folding of the rocks was not a sudden event, so marine, then estuarine, and finally river sediments, continued to collect in the synclines (the downfolds) of the London and Hampshire Basins, as the new ranges of chalk hills were forced upwards. Up to 320 metres of sediments were deposited in the London Basin during this time, but the Chilterns became dry land once again. Chalk is a soft rock, but it resists erosion more than the even softer clays and sandstones of Southern England, so it now forms ranges of low hills.
Rivers that formed on the uplifted areas began to erode the hills, leading to the deposition of further sediments in the basins of southern England, including the Lambeth Group of gravels, sands, silts and clays. At this time, the English Channel consisted of a river delta with mud flats and deposits of sand.
A few words about the flint stones
Flint is a common, local building material, which originates in chalk. Flint is a hard form of the mineral quartz and it occurs as banded nodules of various sizes and shapes, particularly in the Seaford Chalk Formation (Upper Chalk). Inside each nodule, the flint is usually dark grey, black, green or brown in colour, and it often has a glassy or waxy appearance. A thin layer on the outside of the nodules is usually white and a rougher texture.