The Dolomites are a mountain range located in north-eastern Italy. They form a part of the Southern Limestone Alps, which in turn are part of the European Alps that run in a large crescent shape from France through Northern Italy, Switzerland, Austria and Slovenia. The Dolomites extend from the River Adige in the west to the Piave Valley in the east. The northern and southern borders are defined by the Puster Valley to the north and the Sugana Valley to the south.
The fantastic scenery of the Dolomites is due to their geology. The jagged and distinctive mountain peaks are quite strange and unusual compared to the rest of the Alps and to the other mountains of the Northern Hemisphere. The main unique feature of the Dolomites is their geological structure. They are mainly composed of two different kinds of rocks, volcanic and dolomitic. The volcanic rock is a metamorphosed rock and is very hard and resistant to weathering. The dolomitic rock is a type of limestone containing very high levels of magnesium.
The name Dolomite comes from the French scientist who observed dolomitic rock in the 18th century. His name was Deodat de Gratet de Dolomieu (1750-1801). Dolomieu was a French chemist and mineralogist. Whilst travelling to Rome in 1789 he collected a strange kind of rock in Valle Isarco, Italy. Later examination showed that the rock was made of a previously unknown combination of minerals: calcium magnesium carbonate, CaMg(C03)2. The word Dolomite is now a scientific term applied to the unique geologic formations of the Dolomite Mountains. It is important to remember that the Dolomites are made up of volcanic rocks, limestones and the unique Dolomitic rock.
The Latemar and the Marmolada the highest peaks of the Dolomites, at around 3343 metres, for example are limestones. The geological processes that formed the Dolomites were in the Permian-Triassic period (200-265 million years ago). They remained undisturbed for more than 100 million years under a great layer of marine sediment. During the Tertiary (between 60 and 5 millions years ago), the collision between the African continent (tectonic plate) pushing north and the European continent deformed the Earth’s crust and huge mountains of sediment were pushed up to form the European Alps. The process would be similar to crumpling up a huge cotton table cloth on a dining room table. The Alps, including the Dolomite region, were created in this Tertiary mountain building period. It is common to find fossils in the rocks of the Dolomites – as so much of the rock was covered with many metres of marine sediment. This sediment was uplifted during the Tertiary period to create the Alps we see today.
The Dolomites are a naturally very beautiful area. Many of the gentler slopes are south facing and very sunny in the summer months. So the area is very popular amongst climbers and walkers. In addition, the high mineral content of the rocks gives the mountains a pinkish hue, especially at dawn and dusk. This phenomenon is called ‘l’enrosadira’ in Italian and means literally ‘becoming pink’. This makes for wonderful and atmospheric walks in the mountains in the early morning at sunrise or in the late afternoon, just as the sun is setting. Lucky walkers can watch the mountains changing colour from grey to pink to violet. In english ‘l’enrosadira’ is sometimes referred to as ‘alpenglow’.
- An explanation of ‘l’enrosadira’ in Italian: L’enrosadira (lett. dal ladino diventare color rosa) costituisce un fenomeno molto caro a tutti gli amanti delle montagne trentine, ed in particolare delle sue Dolomiti. Con questo termine, infatti, si indica il colore rossastro assunto dalle cime delle Dolomiti e che, in alcune ore dell’alba e del tramonto, può approssimarsi gradatamente al viola. Il fenomeno è causato principalmente dalla stessa costituzione chimica delle Dolomiti.
- And on the geology of the rocks – Tali montagne sono infatti formate principalmente dalla dolomia, una roccia sedimentaria carbonatia costituita preminentemente dalla dolomite, la quale è a sua volta un composto di magnesio e carbonato di calci. ‘Dolomite’ is really an enriched limestone with very high levels of magnesium.
- The effect of ‘l’enrosadira’ on Tofana di Rozes, Dolomites, Italy:
With thanks to John Eaton for asking about The Dolomites!