Normally you just wouldn’t get a shingle cliff! The smooth stones slip against each other and do not form a vertical face. Add a little sand to the mix though and it sets like concrete. This is what happens when coastal defence engineers use marine aggregate, either material dredged from offshore deposits, or shingle bulldozed up from below the high tide line. It has sandy silt added to the mix.
What then happens is that when the sand-shingle mix comes under attack from waves chunks fall off the leading edge to form a vertical cliff like this.
All of which Read the rest of this entry »