Prepared by the Case Histories Committee for the Engineering Geology Division of the Geological Society of America, these histories are intended as reference material for the practicing geologist and for the college student. This volume, the ninth in the series, contains the following papers: Rapid excavation and the role of engineering geology; The engineering geologist’s role in hard rock tunnel machine selection; Some geological structural influences in quarrying limestone and dolomite; Geologic factors in rapid excavation with nuclear explosives; Theory of spacing of extension fracture; Experimental investigation of sliding friction in multilithologic specimens; Total systems approach to rapid excavation and its geological requirements; and more.