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The emergence of the Dolomites

From plain to mountain range

It is clear that the Dolomites have not always been mountains. Millions of years ago, this area was a huge plain which, after centuries, became a tropical sea dotted with several atolls and volcanoes increasing in size over time. Later on, the whole area sank into the ocean until the Pangaea emerged, then Africa and Europe collided and this compression generated imposing and towering mountains: the Dolomites.

Example of stratigraphic succession in the Dolomiti Friulane: the bell tower of Val Montanaia | Courtesy of: Turismo FVG - Mario Verin Three processes have generated the Dolomites: lithogenesis, the transformation of sediments into rocks; orogenesis, the rising of a mountain range from the sea and morphogenesis, the modeling of rock faces by the action of atmospheric agents. All this is well represented by the Dolomite rock: every rock layer which forms the Dolomites corresponds to a specific geological era.

The geological history of the Dolomites took place about 280 million years ago, during the Permian, when an ancient mountain range, placed on the edges of an oceanic gulf, began to sink: finally, the Dolomite area became a warm vastness of water. Large amounts of sediments began to deposit, then an intense volcanic activity led to the deposition of porphyry. Starting from around 240 million years ago, some organisms, requiring light to live, began to build reefs, atolls and small islands. The existence of this beings is clearly visible on the Dolomites, now representing a fossil archipelago unique in the world.
This era was also characterized by another remarkable event contributing to the uniqueness of the Dolomites UNESCO World Heritage Site: volcanism. For a long time major volcanic eruptions affected this region so that lava and volcanic rocks buried and changed the existing reefs. 236 million years ago, in the Ladinian time, volcanoes stopped their activity, were eroded, their rocks started to settle in the sea and the organisms could restart to build coral reefs: a massive coastal plain was formed.

228 million years ago, in the Norian, the Dolomites’ region was once again invaded by the sea and this led to the appearance of carbonate deposits. It was in this time when dinosaurs started to inhabit this plain, as proved by the recent finding of some footprints. About 210- 190 million years ago, between the Triassic and the Lower Jurassic, there was a new phase of sinking which led to the depositing of new shallow-sea limestone. Progressively, between the Upper Jurassic and the Cretaceous (approximately 170 and 65 million years ago), there was a massive depositing of fine limestone and marl sediments (sedimentary rock made of clay and calcium carbonate).

At the end of the Cretaceous, due to the clash between Europe and Africa, this sediments began to emerge so to form a mountain range. During that age, the Earth’s tectonic deformation were intense elsewhere but not on the Dolomites and this demonstrates once more how unique and special this mountains are.