sentence: Some steep hills are the remains of volcanoes.
sentences_before: The bedrock is made up of differently-coloured sandstones. The hilly landscape is formed by way that the sandstone wears down evenly.
sentences_after: The volcanoes were active in this area about 15-20 million years ago.
concept_name: steep hill
headings: Altenbrunslar Geography
categories: Villages in Hesse