A mudslide of hundreds of tonnes of peat has closed the N59 Galway-Clifden road, some 8km (five miles) east of Clifden town in Connemara.
No one was hurt in the bog movement, which began on Thursday evening on the commonage at Lettershea and continued again in the early hours of Friday morning.
Gardaí have put traffic diversions in place through the Inagh Valley, as Galway County Council crews work to remove the liquified peat from the road in a fleet of 20 tonne trucks.
Galway County Council director of services Liam Gavin said that heavy rain at the weekend, and a cloud burst on Monday, may have precipitated the peat movement after a long spell of dry weather.
Traffic between Galway and Clifden is being diverted through the Inagh Valley via Kylemore and Letterfrack. Mr Gavin said he expected the road would be closed for some hours on Friday.
