A 100 tonne boulder was found amidst the debris exposed as a helicopter was drafted in to assist the clean-up on the A83 Tarbet to Campbeltown route at the Rest and Be Thankful.
A landslip on Tuesday, which followed a heavy downpour, resulted in about 6,000 tonnes of mud and rock shifting on the hillside.
The torrent followed the closure of the vital route and though initial efforts to remove the debris took place it is understood an additional 100 tonnes washed onto the A83 overnight between Wednesday and Thursday.
Motorists in the area, which has been blighted by landslips in the past, can usually divert by the Old Military Road, but it too has been rendered impassable.
Specialist engineers have been drafted in to conduct surveys to determine how the routes can be safely reopened.
The huge 100-tonne boulder was discovered on a steep channel above the A83 with the helicopter using water bags to manoeuvre it into a safe location.
Eddie Ross of Bear Scotland said “rigorous geotechnical assessments” were underway yesterday as efforts to assess the full extent of the damage began in earnest.
He welcomed a good weather window which should allow the challenging work to take place swiftly, but he said: “All efforts are in place to address the landslip as quickly as possible, however, safety is paramount and we cannot open either the Old Military Road or the A83 until we are absolutely satisfied that the routes are safe.”
He said Argyll remains open for business and thanked locals for their patience.
Locals leaders have called for a permanent solution to prevent a repeat of the incident.
Highlands and Islands MSP Donald Cameron yesterday wrote to Transport Minister Michael Matheson in a bid to find a solution.
Mr Cameron said locals are being treated as “second class citizens when it comes to our vital transport infrastructure”.
He added: “These repeated setbacks, which include continued concern about the state of the ferry service, are undermining business confidence and putting at risk our prospects of economic recovery after the Covid-19 crisis.
“This is not just about roads. It is about jobs, investment and our ability as a community to retain our young people and families.”