The Mon Klint are chalkstone cliffs rising more than 100m on the eastern side of the island.
From the nzherald.co.nz
Ralston's left-handed severing of his right forearm, which was pinned between a chalkstone boulder and the canyon wall.
From the online.wsj.com
He winds up wedged between two chalkstone walls, the boulder having lodged itself, with a kind of horrific granite permanence, against his crushed right arm.