The granulite terrace ended at the cliff edge of an underground cliff that dropped three hundred meters into the blinding expanse of the Sea of White Flame. Here, at minus nineteen thousand one hundred meters, the bedrock was composed of metamorphic quartz so dense that Arthur’s steel-tipped pitons could barely scratch the surface.
The air at the cliff edge smelled of scorched metal and ancient ozone, carried on blistering gusts that rose from the churning white expanse below. Arthur stood near the drop. He could see the waving heat rising heat currents forming visible vortexes of white-hot gas that twisted into the cave roof thousands of meters above.
He crouched on the glowing granulite, using a magnetic leveling gauge to assess the deep-rock inclination of the shelf. The bedrock was tilting three degrees to the south-west. A clear indicator of earth-shaking subsidence caused by the drainage of sub-crustal magma into Vault Two.
“The mantle shelf is actively deforming under differential pressure,” Arthur observed aloud, his voice recorded by the audio metal pen clipped to his lapel. “We need a deep load-bearing anchor that penetrates through the brittle upper granulite into the ductile dense green rock layer below. If we mount the relay on the surface crust alone, the next ground-shaking pulse from Vault Two will shear the housing off its bolts.”
