Brittany has one of the oldest rocks of Europe. The weathering of that rock produces a heavy clay-bound soil. That soil is not that rich and hard to grow crops upon. Except potatoes, onion and carrots. France was one of the last European nations to eat potatoes, but Brittany was one of the first in France because nothing much was growing on the land of Brittany. They have a stew here names "Ragoût de berniques" meaning a stew made of nothing.