Little or nothing is known by the profane public about the hydrothermalism. When I ask geoGata's clients in our geology tours about this term, that refers to a phenomenon whose effects are present throughout the Natural Park of Cabo de Gata, spas becomes quickly the theme of the chat. Whithout any doubt, natural spas are related to hydrothermal processes, but not much more is usually known. Health or recreational use are based on certain chemical and physical propertiesthat make those waters make attractive in one way or another for humans, as well as the "health of mind" that accompanies water treatments. Another phenomenon related to hydrothermal circulation are the well known and evocative geysers and fumaroles, which are associated with hydrothermal processes of volcanic origin.
In my long experience as a geologist guiding family and friends, and in that I accumulated since geoGata exists as a company, one question is the most asked by all people: Where are the volcanoes? Is that mountain volcano? And rather than vanal, it is, if the answer is focused properly, the starting point of a wonderful adventure of observation of nature, a trip in time to a submerged landscape, full of smoking chimneys, coral reefs in a tropical sea, volcanic eruptions and explosions, and creatures sometimes known and sometimes surprising.
A lot was said about the volcanic eruption in El Hierro in late 2011. Alerts, evacuations, headlines in all media, criticism of the authorities, and so on. The eruption ended already entered 2012 and, except for the inhabitants of the island, affected businesses and the scientific community, there ended all. However, occasionally, some people coming to my geoGata geology tours in Cabo de Gata, speaking of that event during our talks on the volcanoes of Cabo de Gata, ask me about those floating rocks that were collected during the first days of the main eruption in El Hierro. Those bicolor smoky fragments, with its whitish interior and dark crust, which were baptized as restingolites (in reference to the town of La Restinga, the nearest to the undersea volcano), had hidden a surprise that, at least from a scientific and informative point of view, certainly exceed the interest of an eruption that, beyond the media attention, was not even the strongest, nor the most damaging, or longer than that 2011.
As you may know, the Natural Park of Cabo de Gata - Nijar is a protected area in the province of Almeria. Not forgetting the natural wealth and heritage, which deserves that and further distinctions, today we will review the mining history of the province that both from its importance and its antiquity, probably have little parallel in the Iberian Peninsula. The dawn of the mining industry in Almería are lost in the mists of time. So much so, that many legends tell of hidden treasures, such as the Cueva de la Sabina, in Dalías, Sierra de Gador, in the mine "of the Phoenicians", and some placed on this earth the King Solomon and relate an incredible discovery made by himself, a vast and mysterious treasure hidden in the depths of this mountains.
The world of volcanoes is definitely exciting. But did you know that the place with the most active volcanism is in another world? The third largest satellite of Jupiter, Io, slightly larger than the Moon, has about 400 active volcanoes. Most surprising is that the origin of this volcanism is anything but conventional. Io orbits Jupiter closer than the other three large moons, Europa, Ganymede and Callisto - the three being called Galilean in honor of its discoverer. The intense volcanic activity is due to the enormous gravitational pull of Jupiter, and also to the interaction with Europa and Ganymede. This is, in effect, "tidal forces" instead of causing low tides and high tides, resulting in tremendous friction in the inner layers of the satellite, which is heated causing volcanic eruptions.
In previous issues we have stated that in the world (and in the Cabo de Gata Natural Park) there are several types of volcanism and volcanic edifices. Moreover, being rigorous it could be said that each volcano represents a different volcanic type. We can group them according to their morphological similarities, to the predominant mechanisms of eruption, or depending on the lithology of the rocks to which they give rise. One of the most characteristic type is formed by volcanic calderas. The formation of a caldera is the result of the most energetic and explosive volcanic process. Strictly, they aren’t generated by an eruption itself, but as a result of the gravitational collapse of a pre-existing volcanic edifice, due to the partial or full emptying of the underlying magma chamber.
Those of you familiarized with science teaching or interpretation have probably heard about geological time, space-time relations governed by Einstein and Hubble’s principles about the evolution of the Universe, and other exciting (but sometimes disquieting under human life perspective) topics. Also the relative importance of the human race in that scenery is since old times under discussion. The changes in the epistemology from old Greek civilization to our days reveal that, in some way, nature rules are relegated to a secondary role. This is frequently revealed by subtle symptoms in our thinking, our behaviour and our speech. The epistemology that dominates our day by day, our rules, and our thinking, (in a reasonable and moderate interpretation) is the Anthropocentrism, which dates back to the Renaissance and Classical Civilizations. It doesn't mean that everything has to be measured and related to the human race, but its central role is anyway undeniable. It is that way also in some fields that should be clearly controlled by Science and Nature's rules.
That Cabo de Gata is a predominantly volcanic landscape is something that I give for granted. This does not mean that all the rocks we find in the Natural Park are, but certainly its most prominent geological feature is the volcanic origin, and volcanoes and volcanic eruptions will focus this week's article . But, what is a volcano?
The broad and comprehensive definition that comes to mind is that a volcano is a more or less extensive point on the surface of a planet which crops out lava, gases and / or hot or incandescent rock fragments, in a more or less continuous way. No matter if there is a mountain or not, or the shape of the terrain, if at a certain point there is expulsion of lava and / or projection of incandescent rock fragments (pyroclasts), this is a volcano.
In November 1963 a remarkable event set the scientific community a buzz: a new island rising out of the Atlantic a few miles south of Iceland. At that time, geologists John Tuzo Wilson and William Jason Morgan were working on intraplate volcanism, namely hot spots. Plate tectonics was just a fascinating novelty in the panorama of earth Sciences. Wilson is credited with explaining the processes which create oceans, the formation of ridges and subduction zones (Wilson Cycle). Years after the birth of Surtsey, Morgan developed his theories on banding and magnetic reversals of the oceanic lithosphere.
Apasionado de la ciencia, la fotografía y los viajes. Geólogo de formación y guía de naturaleza por vocación.