Volcanic Cabo de Gata (Almería)
Many people’s first memories when visiting Cabo de Gata (southern Spain) are the roads as they drive into the natural park. The roads and the small hills, repetitive and small hills.
I will take you to some locations, some clues that remind us of a violent and explosive past. Because this hypnotic beauty was once, when Cabo de Gata was growing up 14 million years ago, a volcanic hell on earth.
In spite of being titanic processes to our human condition, tectonics is part of planet Earth’s growth as a living organism. Every object has a particular density, right?
Well, same thing happens when talking about oceanic and continental plates: some of them float more than others and this sets up their movements. In the event of African and Eurasian plates, their collision made the crust that contains the Alboran Sea thicken, so when it was made thinner again, magma came out of the Earth.
Some time after that, Cabo de Gata’s volcanic episodes were moved by the Carboneras Fault to their current position. The remaining volcanic episodes are still underwater between Spain and Morocco.
We have to be aware that analyzing a place’s volcanic geology is not an easy task. We usually find rests of explosions, avalanches, high pressure gases, faults… Combinations usually depend on lava’s viscosity and the amount of gas in it.
Walking on lava flows
Now that we understand that, I want you to look to this image.
Here you can see the path between Playa de Monsul and Cerro (Spanish word for hill) del Barronal. This landscape was formed approximately 10 to 12 million years ago. As magma came out of Earth, flows overlapped and petrified almost instantly, because of being underwater at that time.
From the top to the bottom we can see the summit of Barronal’s hill, a huge dunefield covered by Agave trees, the famous Monsul’s barchan dunefield and a huge volcanic agglomerate in different tones of grey. At the right we see different lava flows that now forms the coast’s cliffs and beaches.
What we see in the foreground is the path that connects Monsul and the southern hills of Cabo de Gata: Vela Blanca’s and Punta Baja’s domes.
As we starts to walk from Monsul’s beach to Barronal’s cliffs, we will find rocks from different sizes. Small or human-size rock ones, all of them are mixed up in find-grained matrixes with the same origin: flows of thick and viscous lava that did not covered much terrain until they got cold.
I would not recommend this route for those not experienced in hiking, because of the lack of a path. Nevertheless, having the chance to walk on building-size flows is a startling and beautiful experience. After andesitic rocks agglomerates, we find almost without notice another kind of eruption: a more viscous lava (richer in silica) that is petrified in the form of a cliff.
These episodes, during different periods and cooling conditions have resulted in a wide variety of rocks under our feet.
Punta Baja’s columnar joints
Punta Baja, a dome formed by a lava rich in silica, is found in the southern part of the natural park.
At the time of the eruption, this viscous (silica-rich)material blocked the exit. As it got colder, the lava slightly contracted and the resulting rock acquired a hexagonal shape.
Punta Baja’s columnar joints (its scientific name) are breathtaking, as one can cross and touch the wall of a 12-years-old volcano.
What we see now results from making a perpendicular cut to the dome. The mining industry used columnar joints in Punta Baja as a source of cobblestone until the 1940s.
Approximately, at the time Punta Baja was formed also appeared El Fraile’s volcano. But not as we see it now.
First, the ceiling of a magma chamber collapsed because the material inside erupted to the surface. This lava formed the base of the mountain, which extends to Loma Pelada’s small cape.
Fossil-rich deposits on this area tell us that Los Frailes were, during their formation, a small archipelago. Formed mostly by basaltic lava (poor in silica), Fraile (493m) and Fraile Chico (441m) are domes relatively well preserved.
Time passed in Cabo de Gata and all the volcanic material was covered by vegetal and animal life. In Los Escullos, fossil dunefields portray, with a little of imagination, the beach that used to be there 128.000 to 100.000 years ago. Its composition tells us about a past where the sea was warmer and the swell stronger.
Changes in volcanic and sedimentary rocks, animal life and vegetal adaptation are harmoniously combined to form what we currently now as Cabo de Gata.