Jiggers Bank, a main route into Coalbrookdale, had to be closed after rock and other debris slid onto the road on November 28.
Persistent poor weather since then, including frost and heavy rain, have led to further rock falls. And on Wednesday night, freezing temperatures caused another 50 tonnes of rock and mud to slide onto the road.
Councillor Hilda Rhodes, Telford & Wrekin Council's cabinet member for transport and community protection, said: "I appreciate that this will cause a lot of inconvenience both for residents and visitors to the Gorge, particularly given the time of year.
"However, the fact is that the rockface simply is not safe and we are having to design a scheme to secure it. It will be some time before this is completed and we don't anticipate the road reopening until some time in the new year."
Telford & Wrekin Council has said it does not know when the road will re-open, due to the unpredictable weather and the availability of firms to do the job. A major project to secure the rockface with netting is being designed and stabilisation contractors are being sought by the council.
To help local residents, the shuttle bus from Coalbrookdale to Ironbridge has been reinstated and will connect with normal Arriva bus services.
This will continue at least until January 2 on days when the Arriva services run and will be reviewed again then.