This remarkable geologic location is found at Zumaia beach, on the northern coast of Spain. These spectacular rocks tell a little bit of the story of the breakup of Pangaea. The Iberian Peninsula, today made up of Spain and Portugal, is actually a separate tectonic plate from the rest of Europe; the boundary between Spain and France is actually a plate boundary. During the time of the supercontinent Pangaea, the Iberian plate was stuck in-between Europe, North America, and Africa, but as Pangaea broke up, the Iberian Peninsula was pulled away from the rest of Europe, opening basins and creating a series of faults. These basins were flooded with ocean water, and sediments poured into them from the nearby shallow waters, including turbidites – flows of conglomerate, sand, silt, and clay created by submarine debris flows. These sedimentary layers are thought to be those turbidites, formed as debris was shed off of carbonate platforms in the warm ocean waters of the Cretaceous and Paleocene times. The Cretaceous-Paleogene boundary is found within this sequence as well.
As Pangaea broke up, the Iberian Peninsula first moved along with Africa, heading slightly to the south. This motion rotated the peninsula relative to Europe, opening the modern day Bay of Biscay. But, as Africa closed back in on Europe, this peninsula was pushed up against the modern continent, forming the modern day Pyrenees mountains. This compression uplifted and tilted the previous sediments deposited in the basin along the edge of the Iberian Peninsula, forming these tilted rocks.
The term for this deposit, a Flysch sequence, is occasionally used to describe any sequence of marine sediments deposited in a basin, just before that basin is caught in a mountain building event and uplifted to the surface.
Image credit: https://flic.kr/p/2bHzgSh
Reference: http://www.geologypage.com/2017/07/flysch-rock-formation-zumaia-spain.html https://www.reddit.com/r/geology/comments/5wo9ik/geology_of_thrones_zumaia_spain/ http://www.stratigraphy.org/gssp/selandian&thanetian.pdf http://eurasiatectonics.weebly.com/iberian-plate.html https://bit.ly/2L4p5e5
