Yetholm – Staerough Hill is one of many hills composed of lavas from the ancient Cheviot volcano which erupted about 400 million years ago. The huge crag overlooking the Bowmont Water valley is made of a black rock called pitchstone which was used to rebuild Kirk Yetholm church in 1836-1837. Other lava flows on the hillsides are made of andesite lava which is a purple-mauve colour and usually contains tiny white crystals.