One day in 2011, in a laboratory in Amsterdam, a group of scientists went back 55 million years, took the Iberian Peninsula, and smashed it against what is now France. At that time, erosion had turned the peninsula into a nearly smooth slab, but when what is now Spain collided with what was then the southern tip of Eurasia, the scientists saw the Pyrenees, the Cantabrian Mountains, the Central System, and the Sierra Morena spring up before their eyes, like someone moonwalking like Michael Jackson on a carpet and seeing the wrinkles rise. A video now shows this process, which lasted 35 million years, in just half a minute.
For three years, scientists created 21 Iberian Peninsulas using sand and silicone similar to the kind some women implant in their breasts. “We created the Iberian Peninsula over and over again,” recalls Javier Fernández Lozano, one of the geologists at the Amsterdam laboratory. When they had a new Iberian Peninsula ready, the size of a chessboard, they subjected it to a force equivalent to that generated by the collision between the masses that are now Spain and France.
The relief of the Iberian Peninsula, seen from space. / NASA Their goal was to solve a geological enigma. If you observe the Iberian Peninsula from space, you can easily detect a pattern in the western part: the Cantabrian Mountains, the Central System, and the Sierra Morena appear like three waves in a sea of land, separated by 300 kilometers from each other. In the east, that order is disrupted, with the Iberian System leading the way. "We wanted to know why the western part has a periodic pattern, while toward the east that pattern disappears," explains Fernández Lozano, of the Faculty of Geological Sciences at the Complutense University of Madrid.
Hot and cold custard
The key lies in the lithosphere, the Earth's outermost layer, which includes all six continents. The lithosphere floats on another fluid layer, located more than 250 kilometers deep, allowing the continents to dance. Humans have traveled to the Moon, 400,000 kilometers away, but barely understand how what lies beneath their feet works. "On the Iberian Peninsula, very little is invested in understanding what's happening in the lithosphere," laments Fernández Lozano. To complement other techniques used to study the Earth's interior (such as analyzing Earth's gravity or seismic waves), his team opted to build scale models.
None of their replicas of the Iberian Peninsula were the same. Geologists played with the ingredients to change their density and viscosity conditions until the deformation formed before their eyes a relief similar to that of the Iberian Peninsula. They were then able to extrapolate and draw conclusions. “In the Iberian Peninsula, two lithospheres with different behaviors can be distinguished. Let's say that about 50 million years ago, the western part of the peninsula was like cold custard, while the eastern part would have resembled warm custard. When deformation was applied, each part behaved differently,” the geologist explains.
In the western Iberian Peninsula, tectonic forces were more effective and could travel more kilometers because the rocks were older and colder, and therefore more resistant. However, the east was very different. There, the lithosphere was weaker and hotter, as magma had risen from the deep layers of the Earth's interior during the age of the dinosaurs. "It was easy to deform," summarizes Fernández Lozano. The geologist and his colleagues have published these conclusions in the specialized journal Tectonics.
Scientists have condensed 35 million years of prehistory into just half a minute of video.
Creating each scale model required a month of work in the laboratory of Dimitrios Sokoutis at the Free University of Amsterdam. Gerardo de Vicente of the Complutense University of Madrid also participated. Geologists used what little is known about the Iberian Peninsula's lithosphere to produce faithful replicas. Each model was then deformed in slow motion for approximately 17 hours, the equivalent of about 40 million years. A time-lapse video, barely half a minute long, shows the results of three years of research.
On just one occasion, one of the models fell to the floor and burst, ruining weeks of work. "Spain fell through our fingers, just like politicians do," jokes Fernández Lozano.
Source: Matter
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