The images were taken from the highest point of the Loutraki blockage. There is no steep wall to be found. The loose soil is mixed with small rocks which suggests that the blockage is alluvial. The wall could be compromised due to tectonic activity of the fault underneath.

The western slope shows signs of a landslide. So the blockage might be caused by a landside or an alluvial fan (tab the alluvial button for a link to Wikipedia) and the polje therefore might have been open to the Amvrakean gulf prior to that.

Loutraki blockage

Western slope of the Loutraki blockage

Eastern slope of the Loutraki blockage

Looking from the blockage to Amvraki gulf

The soil of the blockage