Environmental Geology in Spain - From 21st Century Pollution to Fossil Atolls
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Photo credit: Katrin Kleemann
Garbage on the road, with the greenhouses of Campohermoso in the background
On the first day of our field trip, we pulled off the high way in Campohermoso where cityscape is dominated by the white plastic of greenhouses. On our way to an ancient volcano, we drove through a landscape that was dotted with garbage.
View from the crater through the Rambla towards the greenhouses of Campohermoso
After we got out of the car, we walked up a Rambla, a dry riverbed, where we looked for garnets – and found them. Through the Rambla we enter the Cráter de la Granadilla, also called El Hoyazo, a volcanic crater. The remnants we encountered here were of a volcano surrounded by a reef. Five million years ago this was covered in seawater and we would have seen an atoll here. An atoll describes a ring-shaped coral reef that encircles a lagoon, it often—as in this case—is located on top of an (extinct) volcano, which is partially beneath the water, so it provides shallow depths for the corals to grow and form a reef.
360° panorama of the crater, which makes it easier to imagine the atoll
Today, walking in the crater is safe, and we encountered one of the basic principles of geology here: enclosed metamorphic rock is older than the rock surrounding it, in this example we found shale surrounded by the vulcanite.
Right above the orientation card you can see the metamorph rock, which has a black and white color.