Tomas drew back the steel sounding rod. He pulled up a core of thick, foul-smelling gray-blue slurry that clung to the iron like greasy lard.
He rubbed the muck between his thumb and fingers. It had no grit, no sand, no stone holding power. It was blue London clay that had been fully soaked by warm water under high-pressure head, transformed by nonstop chemical action into thixotropic slurry.
“Liquefaction,” Nessa whispered, her face pale in the amber light of the safety lamp. “The bearing capacity of undisturbed blue clay is eight tons per square foot. When it liquefies under nonstop water pressure, its bearing capacity drops to less than half a ton. The western foundation of the Great Sky-Spire is carrying twelve tons per square foot. It’s sinking into the earth like an iron metal bar dropped into a tub of butter.”
Tomas stood upright in the flooded crypt. His eyes swept across the massive granite base of Pier Four. Across the bottom course of cut stone, three upright shear cracks had opened, each two inches wide. It ran upward into the cathedral crossing.
The Spire was not merely leaning in the wind. The entire western side of the building was subsiding into the underground mud.
