Councillors had been expected to either approve or reject a proposal to enlarge Went Edge Quarry, near Pontefract, on Tuesday.
But they've now decided to visit the nearby Brockadale Nature Reserve before deciding, so they can assess campaigners' claims that nature and wildlife will be irredeemably harmed by the plans.
Campaigners were dismayed when permission was originally given for the venture by North Yorkshire County Council's planning committee in May.
But the council's chief executive then effectively ruled the call null and void and asked the committee to look at the plans again.
However, 15 minutes into a meeting in Northallerton this morning, the committee agreed to a request by objectors to visit the site again before making their final call.
Councillor John McCartney said that on a site visit in February 2020, members had only been to the edge of the quarry itself, and not to the nature reserve.
He told the meeting: "At the time we didn't know what the key planning issues and we didn't look at the Brockadale site at all.
"I do think that in order to make a decision on this, that we should walk on the Brockadale grass and look around it.
"It's a big site and it would take some time to do so.
"But breathing in the air and walking on the grass would enable us all to know what we're talking about.
"I'm not convinced that if we don't look at Brockadale that the public won't have confidence in this process."
The quarry managers, Went Valley Aggregates, have argued the expansion is necessary to help meet the demand for building materials in Yorkshire.
They insist the impact on Brockadale will be limited.
But the Yorkshire Wildlife Trust, which runs the reserve, is among those who say rare species of plants and animals would be harmed by dust and noise from the proposed expansion.
Local Democracy Reporting Service