CANAL ZONE: Danger: Falling Rock

The most spectacular moment of a transit of the Panama Canal’s great Gaillard Cut is the passage below Contractor’s Hill, whose sheer rock face, blasted off to make the waterway, rises above ships’ decks for 300 ft. Last week it was learned that some or all of this rock face is in danger of toppling into the canal and blocking it. perhaps for months.

Landslides are nothing new for the Panama Canal. Because early geologists designed banks that were too steep, mudflows began even while the canal was being dug. Before stability was reached, more than 250 acres of the adjacent slopes, complete with trees and scenery, slid greasily into the cut. More slides closed the canal briefly in the year it opened. 1914, and again in 1915 and 1932. But Contractor’s Hill, a vast boulder in the ooze, stood like Gibraltar.

In ‘ 338 a canal engineer, slogging through the underbrush on top of the hill, found a crack in the rock. In the years since, it has widened almost imperceptibly. But a month ago inspectors came down off the hill and reported a new crack.

The fissures, a foot or two in width, now trace an irregular line back of and parallel to the canal-fronting face of Contractor’s Hill. Engineers guess that the cracks may run 600 ft. deep. Because it is hard, granite-like rock rather than the soft, clay-shale conglomerate of earlier slides, the face of Contractor’s Hill will make a formidable dam if it falls.

Canal Zone Governor John S. Seybold hopes to head off a slide. After a look at the cracks. Seybold ordered crews to strip off topsoil for a better view of the fissures and to start a road to the hilltop for operations to come. Probable next step: test borings to map the crevices exactly. In the end, it may be necessary to remove the threatening slab. This week two representatives of the Morrison-Knudsen construction company, world’s greatest earth mover (TIME. May 3), flew down to have a look at Contractor’s Hill.