## 4 Results  
### Landslide Characteristics and Dimensions  
The characteristics of this earth movement correspond to a large rotational landslide that affects the clays and lutites of the unit (22). Despite its age, it retains its own characteristics: a main scarp 155 m high, whose upper edge reaches the Cerro de Navillas (1925 m) (Figures 2 and 3). This scarp has an asymmetric semicircular projection and is 1000 m long, covering the entire width of the outcrop of the unit (22), and being the contact with limestone (23) to the north and with sandstones (21) to the south. There is a head at the foot of the scarp with flooded areas (around 1765 m). The landslide extends 1.2 km in length to the river, and the removed mass expands downward with an average width of about 800 m (Figure 3). The area is about 0.75 km\({}^{2}\). As the maximum depth of the failure surface is about 200 m, this slide involves around 150 Mm\({}^{3}\). The most characteristic of the slipped mass is an irregular ridged relief in transverse grooves subparallel to each other (Figures 2 and 3). The foot invaded more than 1 km of the river that moved 250 m to the east, bringing the riverbed into contact between the landslide and the right slope, between levels 1490 and 1540 m, approximately. The slope of the landslide is about 400 m. The foot has a scarp of 20 to 25 m as a result of the deepening of the Urbion river (see Table 1).  
Within the slipped mass, a subscarp (minor scarp) is seen in the upper part where two appreciable water sprout are born at the 1720 m elevation that originates the source of the stream that forms the alluvial fan. There are other small surfaces as a consequence of minor landslides below.  
The mobilized material consists mainly of a mass of lutites and clays, but there are also fragments and boulders of sandstone. In the upper part of the landslide, the material comes entirely from unit (22), but from the middle downwards there are also materials similar to those of the nearby lateral moraine, formed by sandy reddish earth, although their distinction is not easy.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Notation** & **Dimensions** & **(m)** & **Measurement Type** \\ \hline Wd & Width of the displaced mass & 600 & direct (field) \\ Ld & Length of the displaced mass & 1200 & direct (field) \\ Dd & Maximum depth of the displaced mass & 200 & deduced (field profile) \\ Hd & Height of the displaced mass & 400 & deduced (field profile) \\ Wr & Width of the failure surface & 800 & Numerical model (Figure 8) \\ Lr & Length of the failure surface & 1200 & Numerical model (Figure 7) \\ Dr & Average depth of the failure surface & 150 & Numerical model (Figure 8) \\ Hr & Height of the failure surface & 400 & Numerical model (Figure 8) \\ L & Total lengh of the landslide & 1200 & Numerical model (Figure 7) \\ \hline \end{tabular}
\end{table}
Table 1: Dimensions of the landslide of the Picos de Urbion according to terminology of [PERSON] et al. [40].  
The mobilized lutites have undergone an alteration and clayey materials predominate on its surface. This surface alteration of these lutites is a characteristic of these when they are exposed to the atmospheric agents for short periods of time. It is common to verify the degradation of up to 5 m in depth on the slopes cuts of the roads of the area in a few years. It also constitutes a problem in the conservation of the dinosaur ichnite sites when the soil that covered them has been removed.