It is known that in the Upper Jurassic Asturias had an extremely arid climate, and its coasts were low, with no cliffs initially. A huge marsh in which the minor and major traces of all the organisms that survived in that environment were inscribed. The dinosaurs, specific, found in this mud, seat at the same time of numerous fluvial deltas, an ideal place to satisfy your survival patterns. Now, many of the finds and numerous replicas of animals from the time can be seen in one of the most visited museums in Asturias: the Jurassic Museum. Its founding collection is made up of more than 8.000 specimens of fossils coming exclusively from the Asturian Jurassic. The investigations are being carried out by a team led by the professor of Geology of the University of Oviedo, José Carlos García Ramos.
Jurassic Museum - MUJA
In a privileged place on the coast of Asturias a few meters above sea level, is located the ...
The dinosaur coast
A dense coastal strip of more than 60 kilometers It serves as study material for researchers. A natural archive that in this area is arranged in a series of gigantic slices that make up what geographers call statigraphic formations. The specific limits of the Jurassic period on the Asturian coast, those that contain these formations, extend from Cape Torres, west of Gijón, to the stone of Arra, two kilometers east of Ribadesella (two important faults serve as an exact border with the oldest rocks of another type of coast that dates back further, to the Paleozoic). The secondary era occupies a substantial part in the materials of these layers. Traces of gilliopods, saudopods, theropods and others, both bipedal and quadruped, carnivores or vegetarians, are the most abundant data, with measurements ranging from the foot of a pigeon to that of an elephant multiplied by ten. But in this privileged plot of the peninsular coast there are also remains of turtles, crocodiles and marine reptiles, fish, vegetables, trunks, small organisms, traces of jurassic waves, stream marks of that time, and countless other traces.
They have been cataloged 5 different types of geological formations. None of them are exclusive since they are theoretical models. The Gijón Formation It is the oldest (between 206 and 199 million years old), it is located at a height of more than 100 meters and there is an abundance of limestone and fossils of lamelibranchs and gastropods. The Rodiles Training It is 25 million years younger, bones of reptiles and fish already appear here, in addition to fossils of invertebrates. The Vega Formation It has a depth of more than 150 meters, from the limestone we pass to gray sandstones and red shales. It belongs to a time before 154 million years before our era. Here we already find small crustaceans, plant remains, footprints and dinosaur bones. The Tereñes Training It is even younger and dates back to the time when Asturias was a kind of muddy inland sea. Lastly, the Ballast Formation, The youngest of the five, 151 million years old, is also very abundant in fauna and flora finds. In this period Asturias presented a more advanced landscape, populated by small river deltas, marshes and swamps.
What dinosaur footprints will we find?
Although there are many tastings and discoveries, the main attraction of the Asturian Jurassic coast lies in the extraordinary amount of ichnites found. A density and variety of footprints very rare elsewhere. In addition to the classic depressions in the rocks, there are also the "countermolds", very abundant. These are obvious traces that appear upward, due to the effect of sedimentation later in time that covered them.
The walking routes that we propose below could be frustrating if you do not have a guide, hence some minimal descriptive notes are necessary to avoid overlooking the trails:
1/ The shape of the ichnites Whether we find it depends on 4 main factors: anatomy (foot shape), substrate (sediment conditions), behavior (speed, balance of the animal...) and preservation. Therefore, it is not advisable to look for the typical tridactyl footprint that is perfectly defined and marked.
2/ Type of dinosaurs. Based on their mode of locomotion they can be classified into bipeds and quadrupeds. The first, such as theropods and most ornithopods, walked upright. Quadrupeds, such as sauropods and those with horns, plates and armor, did so using both their front and hind limbs. Typically, the tracks of quadruped dinosaurs are wider than those of bipeds as a result of their different body structure. Among those with a quadrupedal habit, sauropods are the most common, the paw prints are circular or rectangular, while the hand prints tend to be semilunar. Both theropods and ornithopods produce generally bipedal tracks, made up of tridactyl tracks. The difference between both types of footprints is not always simple, but theropod footprints tend to be more stylized and have longer, narrower toes.
Walking routes along the Jurassic coastline
The road access that brings us closer to the Asturian Jurassic sites has as its main routes the Cantabrian Highwayor on the eastern slope of the Principality, as it passes through Ribadesella, Caravia, Colunga and Villaviciosa, as well as regional highway 256 and national highway 632, to which we will necessarily have to detour at some point to get closer to the coast.
These are the main sites found to date:
Merón Beach Villaviciosa
There are two alternatives, one is taking the detour from the As-256 regional road to Careñes, where you have to leave the car and take a descending path that starts from the town church in the direction of the beach [900 meters]. The other part of the Argüero deviation, following the signs indicating the beach.
Once there, the journey begins towards the west along the foot of the cliff for about 600 meters until reaching a sandstone stratum of the Lastres formation. On its surface the trace of a sauropod [quadruped] is preserved, formed by 12 consecutive footprints of hands and feet. There are also scattered tridactyl ichnites of bipeds.
Cliffs of Oles Villaviciosa
Starting from the regional As-256, at the height of El Gobernador, take the deviation that leads to Oles and Tazones. Upon reaching the first of these two towns, a very narrow paved road starts on the left and heads north, passing in front of the parish church of Oles, where there is a small parking lot to leave the vehicle. From there, a path begins that must be followed for 900 meters until it joins a path after a 90-degree turn to the west, which ends just above a broad stratum of sandstone slightly inclined towards the sea.
There are 12 bipedal dinosaur tracks oriented in various directions. The rocks belong to the Lastres formation and among them several sandstone strata with undulating surfaces due to Jurassic water currents and waves stand out.
Tazones Villaviciosa Lighthouse
The explanatory panel is located at the beginning of a path that starts on the left side of the road that leads to the lighthouse. Following the signs you access the cliff after a journey of 1.300 meters.
Right there, on a slab of rock slightly inclined towards the sea, is the first tridactyl dinosaur footprint. From here, continuing to the right [east] you access the surface of a sandstone stratum, inclined about 25 degrees towards the sea, which shows a multitude of tridactyl ichnites that intersect in various directions and constitute several traces, as well as a tail drag imprint. This constitutes a rare example in the fossil record, since, unlike what was thought until recently, dinosaurs walked with their tails upright to maintain balance.
In adjacent strata with the same orientation, various ichnites of hands and feet of quadruped dinosaurs are also observed, seen in plan, as well as the vertical section of one of them of large dimensions, probably from a sauropod.
Another 60 meters further in the same direction, on the vertical wall of the cliff, you can see ichnites of quadrupeds with sandstone filling as bulges at the base of the subhorizontal strata of the same composition or isolated inside gray marl.
Tazones Beach Villaviciosa
On Tazones beach there is an explanatory panel. Starting from the sign itself, you continue along the beach and the cliff, and about 120 meters from it, on the surface of a gray stratum, inclined at about 45 degrees, you can see several tridactyl ichnites belonging to bipedal dinosaurs, oriented in various directions. Some of them constitute a trail.
If we continue for about 480 meters in the same direction, and already within the Vega Formation, of fluvial origin, another tridactyl dinosaur footprint can be seen forming a countermold at the base of a sandstone projection as an eave located several meters high. .
Puerto de Tazones Villaviciosa
On the cliff at the western end of Tazones and a few meters after passing the port breakwater, a magnificent example of a vertical fault can be observed within an alternating succession of sandstones, shales and marls. A few meters further on you can see several examples of vertical root tracks surrounded by a pale green halo on a background of reddish rock representing Jurassic paleosols.
Lastres Colunga Cliffs
From the coastal road N-632 at Colunga, take the regional road As-257 that leads to Lastres. After passing this town and after traveling 1,5 kilometers you reach Luces, where you take a detour to the right along a narrow paved road that leads to the Lastres lighthouse. About 650 meters before reaching the lighthouse, a path starts straight ahead along which we must travel about 850 meters to the foot of the cliff.
Nearby, and a little to the east, is a loose block of sandstone with two countermolds of dinosaur footprints, one tridactyl of a biped and another crescent-shaped [sauropod]. Continuing along the base of the cliff towards the west for about 300 meters you access some inclined sandstone strata on which there are several tridactyl ichnites and a sauropod track, the latter quite worn by the action of the sea.
You can also see numerous fragments of fossilized trunks of Jurassic trees up to 50 cm. diameter.
Greek Colunga Beach
La Griega Beach is reached from the N-632, turning off to Colunga and there taking the road that goes to Lastres beach and also to La Griega beach. Although to go to it, you have to take a road to the right. There is an explanatory panel on the right bank of the estuary, immediately after passing the bridge that crosses it, very close to the campsite. From here, continue towards the cliff on the eastern part of the beach. About 500 meters from the explanatory panel, two decimetric-scale protuberances appear on the surface of a loose block of red sandstone that correspond to countermolds of a handprint and a footprint of quadruped dinosaurs, oriented in opposite directions.
Continuing along the same edge of the cliff for another 150 meters you reach a sandstone stratum gently inclined towards the sea whose surface is crossed by joints [cracks of tectonic origin] in various directions. Less than a meter above is a gray limestone containing tiny gastropod fossils and several large [up to 1,3 meters in diameter] rounded depressions. They are ichnites of large quadruped dinosaurs that show a bulging peripheral ridge. These are the largest ichnites in Spain, and due to their dimensions they can be considered among the largest in the world. The dinosaur that produced them had to be a specimen of colossal dimensions, it was a gigantic quadruped sauropod, whose weight could range around 100 tons. Apart from these, you can see a trail made up of six footprints that also correspond to a smaller sauropod.
Laterally and on the same surface, other tridactyl ichnites appear that form a trail that is somewhat more difficult to identify. About 30 meters further on, some red sandstones from the Vega formation can be seen, which contain traces of pale green verticalized roots, corresponding to ancient paleosols located in areas lateral to the bed of a Jurassic river. The distance between the explanatory panel and the end of the itinerary is about 600 meters.
Vega Ribadesella beach
Access from the N-632 coastal road is located around the town of Torre, about 6 kilometers east of Ribadesella. From there starts a 1,8 kilometer paved road that leads to Vega beach.
A few meters from the eastern end of the parking lot you can see formations that contain abundant marine fossils. Above them there is a layer of conglomerate of siliceous stones one meter thick; 8 meters above you can see a sandstone stratum at the base of which there are several tridactyl footprints of bipedal dinosaurs. The geological composition is typical of this Vega formation of eminently fluvial origin. It is not very accessible.
Cliffs of Tereñes Ribadesella
Take the road up to Tereñes until you reach a stop where it makes a sharp turn to the left, at a crossroads. From here, where the explanatory panel is located, you take a narrow road that descends slightly for 200 meters, from where a path begins on the right that leads to the cliff.
On this particular coastline an inland sea lapped gently, protected from the liveliest seas by a geological formation like a dam.
Once there, the route begins from right to left [towards the west]. Various dinosaur icnites can be observed, among which three tracks stand out, two of bipedal and tridactyl dinosaurs and another very spectacular of quadrupeds, in which hand and foot prints can be seen. They are located on a flat and inclined rock as is customary in these cases. The first scientific tasting of these footprints concluded with "dinoturbation", that is, a mass of arbitrary footprints, as a result of a massive gathering of dinosaurs of all conditions, in the same place. However, recently the theory has changed. And if the length of the step, their size, and the orientation with respect to an axis are analyzed, it is discovered, surprisingly [and this is a finding of great relevance in continental Europe for dinosaurs], that the traces They are parallel to each other, with an astonishing symmetry that tells us that those "monsters" walked in a pack through that place, taking a leisurely stroll and bringing out their gregarious behavior. Most of the footprints correspond to herbivorous bipeds, although it is surprising to see how at the top of the rock another different trail advances perpendicularly towards the first ones. They have sharper fingers, they are carnivorous bipeds, which commonly swallowed the former. Thousands of years may have passed between the footprints of the herd and those of the carnivore.
In a small cove about 90 meters southwest of the Forno rock there is a block of reddish sandstone fallen at the foot of the cliff in which there are small tridactyl footprints created by bipedal dinosaurs.
The total route along the base of the cliff that contains the main ichnites as well as very striking examples of Jurassic desiccation cracks is about 400 meters.
At the west end of Santa Marina beach, at the end of the so-called Mirador del Pozu, there is an explanatory panel. If you look towards the south, you can see gray Carboniferous limestones that stand out in the relief of the vertical wall.
Near the end of the walk we find an alternation of marl and limestone interspersed with sandstone, which extends along the cliff to the west. It shows various levels rich in very small lamellibranchs, as well as desiccation cracks and frequent dinosaur icnites. These appear on the surface of the strata as depressions with an oval or tridactyl outline.
On the same descent to the cliff from the viewpoint at the end of the walk you can see some of these footprints. From here and continuing about 150 meters to the west along the base of it, there is a large slab of sandy limestone inclined to the sea at about 80 degrees. On it there are several traces of sauropod [quadruped] footprints.
Text: © Ramón Molleda for asturias.com