A massive 100,000 tonnes of material is thought to be moving in a hillside landslip that has caused the closure of a train track.
Rail passengers from Sheffield to London are facing disruption as work to stabilise the hillside above the line through Unstone, near Dronfield, goes on.
Wet weather caused the hillside to become extremely unstable, and last week one of the two tracks had to be closed for safety reasons.
A team from Network Rail are carrying out investigations into the cause of the slip and the track is expected to reopen in four to six weeks.
A spokesman for Network Rail said: “The work we are doing now is to allow the railway to reopen safely. Engineers are likely to be on site for several months fully fixing the slip to make sure it can’t happen again.
“Approximately 100,000 tonnes of material is believed to be moving.”
Letters have been sent to residents about the work. Wagons helping to clear the site are also stopping for two hours each day to ease traffic during peak times.
Trains are being diverted with extra journey times.