The underwater landscape during the last stage of the Early Cretaceous is characterized by blocks of continental crust that are submerged at different depths, as is still the case today off the coast of the Bay of Biscay. On the highest blocks, organisms enjoy higher bioproductivity than in the deep sea, as fishermen know well.**

But on the paleo-high of Mutriku something special happens, the ammonites are much more larger than in other areas. We will look closely at the evidence and learn about the local geology closely related to the stretching of the crust that accompanies the opening of the Bay of Biscay.**
We will learn about the biology of ammonites, an emblematic marine animal of the Cretaceous.

After a walk on the rocks of Zazpi Hondartza, we will visit the Nautilus museum which houses a very important collection of ammonites and other fossils from the Mutriku cliffs. During the walk to the museum we will learn more about the Mutriku fault.**

The walk has a limited height difference and part of is over bare rocks.**

Recommended for children with an interest in natural history ages 12 and up.