section_path: Geography/Geology
section_name: Geology
paragraph_text: Geology
  
  The geological history of Europe traces back to the formation of the Baltic Shield (Fennoscandia) and the Sarmatian craton, both around 2.25 billion years ago, followed by the Volgo–Uralia shield, the three together leading to the East European craton (≈ Baltica) which became a part of the supercontinent Columbia. Around 1.1 billion years ago, Baltica and Arctica (as part of the Laurentia block) became joined to Rodinia, later resplitting around 550 million years ago to reform as Baltica. Around 440 million years ago Euramerica was formed from Baltica and Laurentia; a further joining with Gondwana then leading to the formation of Pangea. Around 190 million years ago, Gondwana and Laurasia split apart due to the widening of the Atlantic Ocean. Finally and very soon afterwards, Laurasia itself split up again, into Laurentia (North America) and the Eurasian continent. The land connection between the two persisted for a considerable time, via Greenland, leading to interchange of animal species. From around 50 million years ago, rising and falling sea levels have determined the actual shape of Europe and its connections with continents such as Asia. Europe's present shape dates to the late Tertiary period about five million years ago.
  
  The geology of Europe is hugely varied and complex and gives rise to the wide variety of landscapes found across the continent, from the Scottish Highlands to the rolling plains of Hungary. Europe's most significant feature is the dichotomy between highland and mountainous Southern Europe and a vast, partially underwater, northern plain ranging from Ireland in the west to the Ural Mountains in the east. These two halves are separated by the mountain chains of the Pyrenees and Alps / Carpathians. The northern plains are delimited in the west by the Scandinavian Mountains and the mountainous parts of the British Isles. Major shallow water bodies submerging parts of the northern plains are the Celtic Sea, the North Sea, the Baltic Sea complex and Barents Sea.
  
  The northern plain contains the old geological continent of Baltica and so may be regarded geologically as the "main continent", while peripheral highlands and mountainous regions in the south and west constitute fragments from various other geological continents. Most of the older geology of western Europe existed as part of the ancient microcontinent Avalonia.