Scree

Marker 19Limestone is made up of thin layers topped by thicker ones. Water penetrates into the rock’s interstices and, when it freezes, fractures it. The base layers are more fissured and therefore eliminated more quickly. That is how the overhangs you can see at three different heights were created. These rocky environments have an important ecological role because they are a refuge for certain species of plants (French-leaf sorrel) and animals (little owl). A little further down, some seeps support wetland vegetation: horsetails, hemp-agrimony. This is also a meeting-point for many butterflies (great banded grayling, marbled white), which are the only creatures that can reach the nectar deep inside hemp-agrimonies and plume thistles.