Saturday, 29 February 2020

GeoStudies in Mallorca

GeoStudies in Mallorca

I have recently returned from an excursion to Mallorca, arranged by Geostudies. This article is intended to give a broad overview of the trip with a few pictures of the highlights. No great geological insights are given - only a flavour of the geology of Mallorca.

The areas covered are indicated in the following map.

We arrived on the island on the morning of Monday 17th February. After lunch our (small) bus took us to the peninsula with Alcudia at its base. Highlights were a nappe of Upper Jurassic with a filling of Lower Cretaceous.

Nappe - the line of pine trees mark the Lower Cretaceous. Above and below are cliffs of Upper Jurassic limestone.

And chevron folding.

Chevron folding

Tuesday took us to the South-West side of the island where we looked at the oldest rocks - Triassic - Bunter, Muschelkalk and Keuper. It was a dull day and the rocks, while being very interesting, were not photogenic. But we did find a nice restaurant atop 1,000 foot cliffs. And it had good coffee.

Wednesday was our only day without a visit to a beach. Instead we went to the Cuber reservoir to look at Jurassic limestones forming the highest peaks of the island.

Puig Major (1,436m) seen across the Cuber reservoir. Note the road hairpinning its way up the Jurassic limestone mountain. The dome on Puig Major protects radar antennae.

The spectacular scenery was not what I was expecting on Mallorca.

Thursday was intended to be a leisurely walk along a beach looking at Oligocene and Eocene sediments. We should have been warned as getting down to the beach was complicated as our GA guide (30 years old) did not specify how to get there. But once on the beach we were fascinated by looking at conglomerates, micrites, marls, lots of faulting and shattering and, not least, some oncoliths and stromatolites.

But the walking was not easy. There was a lot of scrambling over boulders. And then the beach came to an end! Going back was not an attractive option, so we decided to wade the short distance to where we knew there was a civilised beach with a restaurant.
Extreme beach geology. Photo taken with my phone - that is my finger on the lower left.

Fortunately the water was reasonably warm. This was the non-geologic highlight of the trip.

Friday took us to Randa and Cala Pi. At Randa we looked for nummulitic limestone and found it in an abandoned quarry. Also turbidites. We retreated from the roadside exposure to avoid being run over by the multitude of high speed cyclists racing up and down the steep road.

Examining turbidites at Randa

Then to Cala Pi which is a rather beautiful spot with the added attraction of lots of fossil corals.

Cala Pi

Saturday was spent looking at Cretaceous limestones on the North East corner of the island. These were much deformed by tectonism and were covered in may places by Recent arenites.

Cretaceous limestone covered by recent sand dunes

Our last day, Sunday, was spent on the Formentor Peninsula, which has some of the most spectacular scenery on the island. It is dominated by thrusting. Generally it is Lias limestone over Oligocene/Miocene shales. The best example was beneath a hotel in Cala San Vicenç.

Lias limestone thrust over Oligocene/Miocene shale.

Further north we saw tall, white, limestone cliffs towering over blue seas.

The Formentor Lighthouse at the end of the peninsula.

On the way back down the peninsula we stopped at the road tunnel and looked at yet another thrust plane lowering over the road.

Thrust plane 

And then the next day we flew home. 

I hope this race through our trip to Mallorca whets your appetite to visit this wonderful island.

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