The colours of time: Villages north of Madrid. 

30/03/2020

In the province of Segovia, some villages are reddish, almost burgundy in color, while at a few kilometers, they are black or yellow. Did the villages have crazy majors? No. The coloring is due to what lies beneath. Discover the 'geodiversity' of this part of Spain. 

2017 © Kathelijne Bonne. 

One hour driving from Madrid to the north, you find yourself in gently rolling hills against an impressive mountain backdrop. This region is known to visitors as La Ruta del Color, The Route of Colors, thanks to its unique natural red, yellow and black villages. It is not well known to people in the big city, but this garantees absolute tranquility.

Detail of a wall in Madriguera. (photo: KB)
Detail of a wall in Madriguera. (photo: KB)

The remarkable coloring is due to the alternation of the rock types used. Although the villages lay only a few kilometers apart, more than 400 million years of geological evolution spans between the building blocks of the black villages and those of the red and yellow villages. 

Black villages.

The tiny medieval village of El Muyo is made up entirely of slabs of black slate (in Spanish: pizarra), extracted from the foot of the Sierra de Ayllón mountains. Similarly, the villages of Becerríl, El Negredo, and Serracín were constructed from black slate. Not much people live here fulltime, most of the villagers migrated to Madrid. The slate of the black villages formed during the Silurian Period, which spanned from 443 to 419 million years ago. Before the Silurian, there was only life in the sea, the land was barren. But the Silurian was the time when water-dependent creatures first peeped above the water surface to start exploring the shores, to finally colonize the land with life for good. 

A house in El Muyo built of of slabs of black slate. In the foreground (the unpaved street) you can see the slate in situ, in a rock outcrop. (DavidDaguerro de Madrid / CC BY-SA 4.0).
A house in El Muyo built of of slabs of black slate. In the foreground (the unpaved street) you can see the slate in situ, in a rock outcrop. (DavidDaguerro de Madrid / CC BY-SA 4.0).

And where was Spain during the Silurian Period? Most of the country was immersed in a shallow, wide sea at the northern edge of the supercontinent of Gondwana. In this sea, the water was poor in oxygen. As a result, no oxidation took place. Instead, deceased organisms that slowly sunk to the seabed did not decompose or rot, and the organic matter was preserved within the seafloor sediment. Layer after layer settled on the sea floor, accumulating as black clay. The black color is the result of the abundancy of organic material. 

Red villages

Madriguera is a well-maintained red village with some rural guest houses for tourists (at the time of writing). Thirty people live here all year round. It is livelier and lovelier than El Muyo. Jasmine, roses, and hollyhocks bloom in neat little gardens. 

But why are the houses here so red, burgundy, almost purple, when they were black a stone's throw away? The walls are made of coarse chunks of heterogeneous rock, held together naturally by loam and clay. Oxidation of iron in the loam gave it its typical red color. This coarse rock was deposited in this area by fast-flowing rivers from the adjacent mountains during the last 5 million years. 

Red walls of Madriguera (photo: KB).
Red walls of Madriguera (photo: KB).

Yellow villages such as Alquité and Martín Muñoz de Ayllón are made up of quartzite, a very hard type of rock, from the same age as the red stone. 

With the help of tourist maps of the province of Segovia, you can walk across the fields from village to village. Places where you can find fossils are shown on the map. Do take a picnic with you, because not every village boasts restaurants or bars, ... or any other sign of human presence.

Yellow bricks in Martín Muñoz de Ayllón (photo: Rowanwindwhistler / CC BY-SA 3.0).
Yellow bricks in Martín Muñoz de Ayllón (photo: Rowanwindwhistler / CC BY-SA 3.0).

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Source: 

Melendez Hevia, Ignacio, 2004, Geología de España: Una historia de seiscientos millones de años. 288 p.