Strata movement indicator

摘要

A strata movement indicator includes at least two lengths of suspension wire respectively for remote and near anchors locatable in the same borehole. Each wire carries a cylinder provided with indicator markings, the cylinders being moveable with respect to one another and to a reference tube fixed in the mouth of the borehole. Relative movement of the cylinders with respect to one another and/or to the reference tube indicates the degree of strata movement.