ROUTE 1 WAYPOINT 9 AND ROUTE 2 WAYPOINT 9

Waypoint 9: The Dolomites Map route 1  (Map Route 2)

We walk through the village and end the creation of "Hortezuelos"  that defines the depostional sequence DS-2. Even though we have finished our peculiar sequential and sedimentary analysis, the grat oscilations of the sea level during the superior Cretacic period continued to affect and generate sea rocks.

To start, there are two updates to highlight, on the one hand we will no longer refer to rocks of Conician age, but of Santonian age (86,3-83,6 M.Y) and on the other hand we are no longer in the creation of "hortezuelos" but in the creation of dolomites of Montejo. This is of high relevance as we have to change our vision completely, if before we focused on the alternation between loam and chalky rocks, we now only have one dolomitic unit ( with dolomites in variable strata). Lets not forget that we are not speaking about chaly rocks, but about dolomites ( instead of CaCO3, is CaMg(CO3)2) this change is due to the circulation in the rocks of water with a high concetration of magnesium provoqued by rainwater or any others.

We can also highlight something that might seem irrelevant, we now find ourselves on an isolated block where there are dolomite outcrops  (from the pelota court until the cementery) and we are surrounded by rock units associated to the reef (as we will see agian at waypoint 10). This may be caused by several factors as geological faults or small creases that have preserved this small enclave.

This rock, watching closely and carefully may resemble us , at least partially, to the first bar. However, if we looked at it with a magnifying glass we would not see any fossil fragment but many small glasses together, what it is called sugar aspect formation.

But, why are not there any fossils? It is due to the characteristics of the formation of dolomites. The replacement of ions generates a loss in the original structure so all of the fossils that we could have dissapear.




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RUTA 1 PUNTO 1 Y RUTA 3 PUNTO 18

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Punto 1: Las Margas iniciales  (Plano Ruta 1)   (Plano Ruta 3) En este punto se observa la primera unidad blanda de la secuencia sedimentaria que forma DS-2. Esta unidad representa  hasta los primeros estratos que dan cierto resalte al cortejo TST, es decir Transgresivo, asociado a una rápida subida del nivel del mar lo que da una rocas de origen marino relativamente profundo. La primera unidad dura que da un ligero saliente mayor representa la superficie de máxima inundación (MFS). A partir de este nivel la tasa de subida del nivel del mar se desacelera haciendo que se vea compensado por el aporte de sedimentos hasta que inicia el cortejo de alto nivel del mar (HST). Paleontológicamente en esta unidad destacan unos ostreidos de gran tamaño, con una valva inferior muy pesada que le permite estabilizarse en el sustrato. Tras la muerte del organismo suele ser colonizado por esponjas y Serpúlidos. También es frecuente encontrar Ammonites como Prionocycloceras iberiense , Tissotia Sp. ,
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ROUTE 3 WAYPOINT 17

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Waypoint 17: Ochre Dolomites (Route 3 Map) At this point it is possible to find the ochre dolomites seen at point 8 again, although the quality of the outcrop is somewhat worse. We can see how it is made up of red dolomites formed by small oolites. All of them are associated with the moment when the sea level began to rise, but still with a low water level.
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ROUTE 3 WAYPOINT 8

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Waypoint 8: Ochre Dolomites (Route 3 Map) From this point we can see a small farm with roe deer, but the presence of a unit of ochre dolomites is particularly noteworthy from a geological point of view. The relevance of this unit is that it marks the beginning of the stratigraphic sequence that contains the main geological elements of interest in the municipality. This unit marks a period of low sea level with almost aerial exposure of the sediment, which generates oxidation and gives these ochre colours.
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