Professor Aldous Nettleford arrived in Bobington on Monday. By Tuesday evening he was on the ridge.

The author of The Thermal Earth, the leading authority on continental geothermal systems at Caldwell University, and a man whose students describe him as “unhurried to the point of philosophical,” did not waste time. He spent three consecutive nights — Tuesday, Wednesday, and Thursday — on the Greymoor Highlands alongside Dr Odette Collis and Dr Maren Ilkley, making observations from multiple positions along the ridge. He returned to the city yesterday morning with soil on his boots and what he described as a preliminary assessment.

The phenomenon, he said, is consistent with a shallow magma intrusion.

“A body of molten rock has risen from depth into the upper crust,” Professor Nettleford explained at a press briefing at the Royal Institute yesterday afternoon. “It is heating the surrounding rock and driving ionised gases through fractures in the overlying strata. The gases interact with the atmosphere at the surface and produce the visible emission — the glow.”

He paused.

“It is not a volcano. There is no eruption risk in any meaningful timeframe. The intrusion appears to be at approximately eight hundred metres depth, and extends along roughly three kilometres of the ridge. There are four discrete emission points, but the uniformity of the spectral signature across all of them indicates a single connected system. They are linked beneath the rock like the chambers of a heart.”

The Greymoor glow is now in its sixty-eighth consecutive night of observation. Dr Collis, who first documented the phenomenon on 3 February from the Cartwright Observatory, estimates it is approximately 35 per cent brighter than at first observation. The rate of brightening has not slowed.

Professor Nettleford’s assessment adds considerable weight to the earlier spectroscopic findings of Dr Collis and Dr Ilkley, who identified ionised nitrogen and trace sulphur dioxide in the emission spectrum — consistent with volcanic or geothermal venting.

What is new is the scale. Where previous observations had described a localised phenomenon, Nettleford places the source as a significant subsurface body extending along the full length of the ridge.

“This is the most interesting geological event in this country in my lifetime,” he said. He did not appear to be exaggerating.

The implications for the Greymoor monitoring station — approved by the Royal Institute and funded at 195,000 florins — are significant. Professor Nettleford recommends expanding the planned survey to include additional deep boreholes and magnetotelluric surveys, which measure electrical conductivity in the subsurface to map the extent and temperature of the intrusion.

“The instruments already ordered from Northcroft will give us surface data,” he said. “But to understand this system, we need to look beneath it. The boreholes will tell us what the rock is doing at depth. The magnetotelluric survey will map the intrusion’s geometry.”

He did not offer a cost estimate for the expanded programme, but acknowledged it would be “substantially beyond” the current budget.

The monitoring station equipment — three wagons from Northcroft Instruments of Edgeminster — has been waiting at Dunvale junction since Tuesday. The Works Committee voted yesterday to approve the access road (reported separately), clearing the path for the convoy to proceed to the station site.

Dr Collis, who has now logged sixty-eight consecutive nights of observation, was characteristically measured. “The instruments will arrive. The readings will begin. And then we will know more than we know now.”

Professor Nettleford will lecture at the Bobington Polytechnic on 15 April as part of the spring series in Founders’ Hall, before returning to the ridge for further observation.