of strata in southern England, producing the London Basin syncline, the Weald-Artois Anticline to the south, the North Downs, South Downs and Chiltern Hills. During the period the North Sea formed, Britain was uplifted. Some of this uplift was along old lines of weakness left from the Caledonian and Variscan Orogenies long before. The uplifted areas were then eroded, and further sediments, such as the London Clay, were deposited over southern England. The major changes during the last 2 million years were brought about by several recent ice ages. The most severe was the Anglian Glaciation, with ice up to thick that reached as far south as London and Bristol. This took place between about 478,000 to 424,000 years ago, and was responsible for the diversion of the River Thames onto its present course. During the most recent Devensian glaciation, which ended a mere 10,000 years ago, the icesheet reached south to Wolverhampton and Cardiff. Among the features left behind by the ice are the fjords of the west coast of Scotland, the U-shaped valleys of the Lake District and erratics (blocks of rock) that have been transported from the Oslo region of Norway and deposited on the coast of Yorkshire. Amongst the most significant geological features created during the last twelve thousand years are the peat deposits of Scotland, and of coastal and upland areas of England and Wales. At the present time Scotland is continuing to rise as a result of the weight of Devensian ice being lifted. Southern and eastern England is sinking, generally estimated at 1 mm ( in) per year, with the London area sinking at double the speed partly due to the continuing compaction of the recent clay deposits. Mountains and hills The ten tallest mountains in the UK are all found in Scotland. The highest peaks in each part of the UK are: Scotland: Ben Nevis, Wales: Snowdon (Yr Wyddfa), (Snowdonia), England: Scafell Pike (Cumbrian Mountains), Northern Ireland: Slieve Donard (Mourne Mountains), The ranges of mountains and hills in the UK include: Scotland: Cairngorms, Scottish Highlands, Southern Uplands, Grampian Mountains, Monadhliath Mountains, Ochil Hills, Campsie Fells, Cuillin Wales: Brecon Beacons (Bannau Brycheiniog), Cambrian Mountains (Mynyddoedd Cambria), Clwydian Hills (Bryniau Clwyd), Snowdonia (Eryri), Black Mountains (Y Mynyddoedd Duon), Preseli Hills (Y Preseli) England: Cheviot Hills, Chilterns, Cotswolds, Dartmoor, Lincolnshire Wolds, Exmoor, Lake District, Malvern Hills, Mendip Hills, North Downs, Peak District, Pennines, South Downs,