Die Cloos’sche Falte

Nestled amidst the impressive rocky landscape of Altenahr lies a small but extraordinary natural monument: the Cloos Fold. This unique geological feature is not a man-made structure, but visible evidence of the immense forces that have been at work here over millions of years.

This steep, vertical rock fold was formed around 400 million years ago by tectonic stresses – that is, movements and fractures in the Earth’s crust that split the rock. Later, erosion caused by water, frost and weathering further shaped this fissure, making it so clearly recognisable today. Our Earth was a very different place back then: a tropical climate prevailed, and many rivers carried sand, silt and small pebbles. These materials settled on the ground and, over the course of millions of years, solidified into rock layers. Later, two huge continents collided and compressed the rock so strongly that the layers buckled and were, quite literally, folded. This is how the Cloos Fold came into being. It was named after its discoverer, the geologist Prof. Hans Cloos (1885–1951). He mapped the fold in detail and wrote a book about it. The Ahr Valley itself is much younger than the fold. It was only about a million years ago that the Ahr began to carve its way into the mountains. The Eifel rose slowly, and the river had to force its way through the hard rock. This created the many bends, steep slopes and the narrow valley that we know today. A visit to this fold in the rock can be wonderfully combined with a hike or a walk through the rocky landscape around Altenahr. It is not a flashy attraction, but a tranquil natural monument that impresses precisely because of its unspoilt nature. If you take the time, you’ll discover the history of the Earth here – preserved in stone.

Pause for a moment, let the tranquillity wash over you and imagine the forces required to split the rock open at this very spot. This is precisely what makes the Cloos Fold such a special place for curious visitors and nature lovers.