There are mountains, and then there are the Dolomites. Pale towers of carbonate rock rising like fossilised cathedrals from green meadows, glowing pink and orange at sunset in the famous enrosadira. I have the privilege of being a guide for the exhibition "Dolomiti: un cammino nella geologia della meraviglia", organised by the University of Padova's Department of Geosciences. Every time I walk visitors through it, I learn something new — and here are a few things that blow my mind the most.
250 million years in a nutshell
Imagine standing where the Tre Cime di Lavaredo are today, 220 million years ago. No mountains. You're underwater, in a warm tropical sea dotted with coral atolls — not unlike the Maldives. Algae, sponges and corals build massive carbonate platforms while volcanic eruptions periodically bury them in ash and lava. These ancient reefs are now the white walls of the Dolomites.
~280 Ma — The first sea
An ancient mountain chain collapses. The Dolomite region sinks below sea level. Porphyry volcanics and early marine sediments begin to accumulate.
~240 Ma — The reef builders arrive
Corals, sponges and calcareous algae construct massive carbonate platforms — atolls and barrier reefs in a shallow tropical sea. Today's white cliff faces are those ancient reefs, turned to stone.
~230 Ma — Volcanic interlude
Powerful eruptions bury and modify the reefs. The volcanic layers are visible today as dark bands in the cliff faces.
~220 Ma — Dinosaurs walk the flats
Tidal flats emerge between reef episodes. Dinosaurs leave footprints in carbonate mud — preserved in rock and found at several localities across the Dolomites.
~65 Ma → today — Africa meets Europe
Continental collision lifts the entire sedimentary stack 3–5 km. Glaciers and erosion sculpt the iconic towers, pinnacles and vertical walls.
But why are they white?
Déodat de Dolomieu, an 18th-century French geologist, noticed that certain Alpine limestones did not fizz with dilute acid the way normal calcite does. The mineral turned out to be a calcium-magnesium double carbonate — CaMg(CO₃)₂ — named dolomite in his honour.
The enrosadira: why they glow
The famous pink-orange glow at sunrise and sunset isn't magic — it's mineralogy. Fine-grained dolomite and calcite scatter low-angle sunlight in ways that darker silicate rocks simply cannot. The result is a natural light show that has inspired artists and mountaineers for centuries — and that gives me a particular thrill every time I see it, knowing exactly which mineral is responsible.
If you're ever in the Padova area, come visit the exhibition. I'll be happy to walk you through 250 million years of wonder.