The rocks of the Troodos mountain range were formed 92 million years ago by undersea volcanos. They were uplifted by the two continental plates: Eurasian and African. They are still moving towards each other, which is why the island experiences high seismic activity.
Follows is a geological description of the route of the Buff ® Troodos Mountain Ultra, expertly compiled by geologists of the Troodos Geopark, our amazing institutional partner.
We urge runners to take some time, either before or after the race, to visit the Geopark Visitors’ Centre – you will come away enriched and enlightened.
THE PRODROMOS LOOP
Running on the top of Olympus is like drilling 60 km into the deep sea. The deepest layers of the oceanic plate are to be found at Troodos Square. The rocks are named ‘ophiolite complex’ and they consist a piece of the oceanic plate that became detached and uplifted above sea level.
Your journey starts with Atalante geo-trail, which consists mainly of harzburgite, rock formed at the deepest depth of the ocean and belonging to the mantle sequence. Mantle is the material under the tectonic plates, which they ‘slide’ on. Along this part of the trail you will come across the Hadjipavlou chromite underground mine, which operated from 1950 until 1982. It closed due to pressure on the commercial price of chromite which was being replaced by other materials and by the appearance on the international market of cheap chromite from South Africa.
A new regime is observed after you leave the Atalante trail and you start running towards Prodromos. You are now discovering dunite. It is one of the plutonic rocks, which were formed in the magma chamber, beneath the zone of sea floor spreading. Dunite is formed at the lower part of the chamber and is associated with the chromite deposits. On your way towards Prodromos you will meet the geosites 45 (486769, 3866957) and 47 (485927, 3867050). The former is a remarkable section which displays the dunite passes gradually to wehrlite and, further down, the wehrlite is in tectonic contact with pegmatitic pyroxenite. The latest is layered pyroxenite. Wehrlite and pyroxenite are also plutonic rocks but formed and upper parts of the chamber.
Now you are heading to the Artemis geo-trail. The main rocks in the broader area are harzburgite, in which small pods of dunite are found. Along the fissures, the harzburgite has been transformed into green serpentinite. A transformation occurred during the uplift of Troodos’ rocks. Africa plate was sinking under Troodos, sea water escaped towards to deeper ground. High temperature in this environment heated the water, resulting in a transformation called ‘serpentinization’.
Finally you are heading back to the Troodos Square checkpoint, via the southern eastern part of Atalante trail. Similar geology as the beginning of the loop is noticeable.
THE PSILO DENDRO LOOP
This loop is breathtaking as runners start from the deepest layers of the oceanic plate at Troodos Square. At the beginning you will notice the deeper part of the ophiolite rocks. At the beginning you are running on the mantle sequence and as you run towards the Persephone trail you are on plutonic rocks. The former are named harzburgite, part of which altered to serpentine. Mantle sequence are rocks formed first, when the oceanic plate was created from undersea volcanos. They are as similar as we can find with the mantle, the high-temperature dense-liquid material that plates are ‘moving’ on.
As you run into the valley you will come across dunite. Dunite is one of the plutonic rocks crystalized first. Plutonic rocks were formed in the magma chamber, beneath the zone of sea floor spreading. You can see dunite with distinctive banded chromite (schlieren) along the trail, at the geosite no. 6 (489922, 3863602). Chromite is a mineral often occur with dunite and mined in the past.
On your left site you can see the under-rehabilitation mine of Amiantos. It was the largest (in area) asbestos mine in Europe and it operated from 1904 to 1988. The mine was reclaimed by the government over 20 years ago. Today it hosts the Troodos Geopark Visitor Center at the former primary school building.
From there and before reaching Persephone trail again you are running on gabbro. It is a black and white rock formed in the upper part of the chamber. A perfect spot to observe it is at the Kalidonia Waterfall. The running water has eroded the ground and gabbro is exposed for anyone interested to observe. On your way to the end point you will encounter similar rocks as at the beginning.
THE AGIOS NIKOLAOS LOOP
This loop is in the Solea valley, the southern part of the Troodos and the highest in elevation.
You will firstly meet harzburgite at Troodos Square but as you run down into to the valley you will come across serpentine with or without asbestos thin veins. Just before you reach Agios Nikolaos church you will find geosite no. 19 (490029, 3869630), in which there is a canyon of Karkotis river cutting through harzburgite with dunite bodies of various sizes.
Closer to the church you will meet the plutonic rocks, which were formed in the magma chamber, beneath the zone of sea floor spreading. In this area is mainly gabbro, a black and white rock formed in the upper part of the chamber. Dunite is the rock formed at the lower part of the chamber.
Along the Kannoures trail, you will see to your right a chromite mine: the Kannoures underground mine. The mine operated from 1939 and it closed in 1982 due to commercial reasons. The deposits are very rich with average concentration of around 52%.