A group in mid-Cornwall against plans to dump millions of tons of china clay waste into a local valley are highlighting their concerns on Sunday.
Imerys says no better site for waste has been found
Clay company Imerys wants permission from the county council to fill a 250-acre site of the Gover Valley.
The newly-formed Gover Valley Action Group is encouraging those against the plans to join them on a nature ramble to look at the area near St Austell.
Imerys said it promised to restore the area it to its former glory.
Opponents to the dump scheme said that valuable ancient farmland, woods, a stream and fauna and flora could be lost.
Imerys said it accepted the chosen site was "not without issues", but that an environmental impact assessment had been carried out.
The clay company is preparing for a meeting with the council in July to discuss the plans.
The ramble will take place at 1030 BST, starting from the valley's Twin Peaks.