The true scale of the blocked path revealed itself only when Tomas climbed to the high watching ledge on the northern wall of the Cauldron.
From forty feet above the gravel floor, the rubble heap looked less like a rockfall and more like a ruined castle wall built by giants. Four thousand two hundred tons of dark, massive pale limestone and white limestone lay wedged between the upright canyon walls. He formed an inverted pyramid of stone sixty-two feet high. The base of the pyramid was over one hundred feet wide, seated directly across the mouth of the natural upright drain tube that plunged three hundred feet into the mountain’s lower drainage system.
Tomas sat upon his ash pack frame, resting his elbows on his knees. Meanwhile, his hands step by step worked his leather wrist brace. His left forearm was aching with a deep, throbbing pulse that made his fingers tingle. But the tendon remained locked and stable beneath the calfskin straps.
“It’s a squeezing arch,” Nessa said, her brass transit mounted on its tripod beside him. She adjusted the fine-scale screw on the level circle, sighting the telescope through the gloom at five key points along the face of the rubble. “Look at the way the boulders are nested. The blast was timed so that the largest blocks fell first. It dropped into the narrow neck of the drain tube throat. Then the backup charges brought down the upper ceiling, showering hundreds of tons of smaller scree on…
