table mountain, tafoni, tagging, tailwater, talus cone, tape, taranakite, tarbuttite, taylorite, tectokarst, tectonic, tectonic cave, tectonic valley, temperature efficiency, temperature log, temporary hardness, tenorite, tensiometer, terminal moraine, terra rossa, terrace, terraced flowstone, terrain, terrane, terrestrial, tertiary porosity, test hole, texture, thalweg, Theis equation, thenardite, thermal spring, thermal stratification, thermocline, thermocouple, thermokarst, thermokarst pit, thickness, thief zone, Thiem equation, thixotropy, thread, threshold, threshold saturation, through cave, throughfall, throw, thrust; thrust fault, tidal river, tidewell, tightest packing, till, tilted aquifer, time base, time lag, time of concentration, time of rise, time-drawdown curve, tinajita, tinticite, toadstone, topofil, topographic divide, topographic map, topography, topsoil, torca, torricellian chamber, tortuosity, total dissolved solids, TDS, total hydraulic head, total pore space, total runoff, total soil-water potential, tourelle, tower karst, towerkarst, turmkarst, trace, tracer gaging, tracer-flow method, tracers, traction load, tranquil flow, transgression, transient, transit time; travel time, transition zone, transmissibility coefficient, transmission capacity, transmissivity, transpiration, transpiration depth, transpiration ratio, transport, transportational process, transverse permeability, transverse wave, trap, traverse, travertine, travertine terraces, trellis, trellis drainage pattern, tri-cam, tributary, tributary river, tributary valley, triple point, tripoly, tritium, Trittkarren, troglobite, troglodyte, troglomorphy, troglophile, troglophobe, trogloxene, trophic levels, trough, True North, true velocity, truncation, tsingi, tube, lava, tubular passage; tube; tube passage, tubular spring, tufa, tunnel, turanite, turbidity, turbulence, turbulent flow, turbulent threshold, turlough, Turmkarst, twilight zone, type curve, tyuyamunite,