At the entrance to Abiego on the road from Bierge there is an interesting collection of over 1000 ichnites preserved in a layer of limestone. They are the fossilized footprints of herds of herbivores, now extinct, that lived on what were meadows dotted with small lakes. They are thought to correspond to the artiodactyla group of mammals, possibly the Anoplotherium or Entelodon.
Between 35 and 40 million years old, they date back to between the Eocene and Oligocene periods. Originally left in mud, the footprints filled with leaf and plant residue, which protected them from erosion.