The cut goes through a vein of mineral which runs across the Bollihope valley. Upstream and downstream there has been extensive quarrying of limestone but this isn't limestone it's a mix of red rusty stuff and white spangly bits (technical terms). All along this vein throughout Weardale there has been mining and quarrying for Lead, Ironstone and Flourspar among other things. I recommend you don't try to eat it.
You can wake up now.