Guess where was I!

For many religious people this place is a holy site since the 12th century. For me it is a natural wonder with many secrets to explore.

When I go to geology trips (apart from fieldwork) I intentionally do not check any geological literature beforehand. It is much more interesting to find out everything by myself, wandering around and trying to read millions of years old events in the rocks.

 

The mountains in this area seem to be a thick sedimentary sequence composed mainly of red sandstones at the bottom and conglomerates on the top. Of course when you look in details it is not that simple but roughly speaking these two units determine the landscape and topography on the large scale. In the sandstones on the lower part, erosion dominantly occurs along river beads leading to the formation of canyons and flat topped mountains. The conglomerates on upper part look like human made statues rising highly above the old cloister. But they are not shaped by human. The process takes two steps: first during tectonic activity rocks are fractured forming vertical joint systems and then erosion widens these fractures giving the mountains the peculiar present day shapes.

The sandstones are fine to coarse grained, sometimes with rare pebbles and clay-like material inside. The redish color testifies of terrestrial environment. The red color is basically a rust. Although sandstones are dominated by quartz grains they usually contain smaller fractions of other minerals. If iron bearing minerals in sand comes in contact with oxygen they form rust thus coloring the sand red. It does not happen in deep water because there is not enough oxygen available. But if the water is shallow or gone the sand tend to oxidize. This particular sandstone looks like typical river delta deposits. So what was once beneath the sea now is a high mountain range.

The conglomerates can form in different environments but they often tell that new mountains were growing nearby. In any case the source area should be nearby otherwise long transport would break the rock down to the sand size. The particular conglomerates are well rounded which means they have spent some time in the water where they were polished by currents of waves. Afterwards the limestone and sand filled the voids between pebbles cementing the material and making it persistent to erosion.

In general the area is spectacular. It could keep sedimentologists busy for years because the exposures are excellent.

Guess the place!

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2 Responses to Guess where was I!

  1. Anonymous says:

    Montserrat. Spain.

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