During this period, the effective-stress paradigm became the central organizing principle for understanding crustal deformation and rock failure. Researchers emphasized hydro-mechanical coupling, recognizing that interstitial fluid pressure lowers the rock's effective normal stress and enables overthrust faulting, fracture-driven deformation, and pressure-dependent strength. The cubic law for fluid flow in deformable rock fractures emerged as the standard model linking fracture aperture to flow rate, shaping groundwater, hydrocarbon, and geothermal transport studies. Insights into the generation and compaction of partially molten rock bridged petrology with geodynamics, showing how melt fraction governs rheology and seismic properties and informing mantle-scale behavior. The mechanics of fold-and-thrust belts and accretionary wedges provided a coherent framework for predicting stable wedge angles from force balance, while dilatancy and strength of sands highlighted how mineralogy and density govern granular deformation. Collectively, the period advanced methodological links between pore pressure, melt processes, and dilatant behavior, enabling more integrated models of crustal deformation across scales.