The California Highway Patrol said the slide washed out earth beneath the roadway and a full closure between the two roads is still in effect.
There were reports that the road might reopen by 4 p.m. today, however Caltrans and the CHP later clarified that the road would need to be closed until at least next Friday at 4 p.m.
A supervisor with the Sonoma County Transportation and Public Works Department's Road Division discovered the slide between Meyers Grade Road north of Jenner and Timber Cove Road north of Fort Ross around 1:10 p.m. Wednesday, Thomas said.
Northbound Highway 1 traffic was directed off the highway at Meyers Grade Road and will re-enter Highway 1 at Fort Ross Road, and southbound traffic was detoured onto Fort Ross Road and re-entered at Meyers Grade Road.
The detour is about six miles long, and motorists should allow at least an additional 10 minutes in travel time, Caltrans spokesman Adam Priest said.
