GERMAN MILITARY GEOLOGY:GERMAN MILITARY GEOLOGY:BETWEEN THE WARSBETWEEN THE WARSBYBYJ. David Rogers J. David Rogers andandGary BonhamGary BonhamEvaluating Crater EffectsEvaluating Crater EffectszzDependent on projectile, Dependent on projectile, objective, rock, and the effect objective, rock, and the effect produced.produced.zzSwamp and Moor Swamp and Moor ––Deep Deep penetration with high mud penetration with high mud column but little damage.column but little damage.zzDrift Sand Drift Sand ––Decreases shot Decreases shot effect but airborne sand = effect but airborne sand = disablement.disablement.zzSoft loam and loamy sand Soft loam and loamy sand ––weakens burst effect, good weakens burst effect, good for artillery positions.for artillery positions.zzCoarse compacted sand, Coarse compacted sand, gravel, residual soil, firm gravel, residual soil, firm loam and clay loam and clay ––full burst of full burst of projectile realized.projectile realized.zzRock and rocky soils Rock and rocky soils ––intensifies burst effect and intensifies burst effect and causes splintering. causes splintering.Studies of Road StabilityStudies of Road StabilityzzDrainage issues Drainage issues addressed in addressed in detail.detail.zzGeologists to be Geologists to be consulted on type consulted on type of material to be of material to be used.used.zzLocation of roads: Location of roads: underlying underlying material, slope material, slope stability, bearing stability, bearing capacity, flood capacity, flood plains.plains.zzCorduroy roads Corduroy roads required in some required in some instances.instances.DitchDrain Pipe ShaftRailroad ConstructionRailroad ConstructionzzRock for railroads was preferred to be igneous and metamorphic rRock for railroads was preferred to be igneous and metamorphic rocks such as ocks such as diabasediabase, basalt, , basalt, graywackegraywacke, , quartzitesquartzites, and , and hornestoneshornestones. . LimestonesLimestonescould be used in emergencies and all other sedimentary rocks could be used in emergencies and all other sedimentary rocks along with granites and along with granites and rhyolitesrhyoliteswere considered inadequate.were considered inadequate.Soils and FortificationsSoils and FortificationsGranite SandDG w/boulderFresh GranitezzType of soil and/or rock must be know for design of long standinType of soil and/or rock must be know for design of long standing fortifications.g fortifications.zzWater from high groundwater tables or drainage must be planned fWater from high groundwater tables or drainage must be planned for and dealt with.or and dealt with.zzLoess soils have highly variable groundwater yields depending onLoess soils have highly variable groundwater yields depending onseasons. Water seepage is seasons. Water seepage is problem.problem.zzClay soils also prone to water seepage, especially between weathClay soils also prone to water seepage, especially between weathered and ered and unweatheredunweatheredzones.zones.zzGranite can be wet or dry depending on weathering of the rock. Granite can be wet or dry depending on weathering of the rock.Underground GalleriesUnderground GallerieszzVictoria Gallery Victoria Gallery ––Begun in the Begun in the hard limestone with blasting. hard limestone with blasting. Moved tunnel to softer sand Moved tunnel to softer sand underneath until it reached underneath until it reached existing limestone caves.existing limestone caves.zz1. Gallery will be flooded due to 1. Gallery will be flooded due to presence of water bearing presence of water bearing sand.sand.2. Gallery will be dry due to 2. Gallery will be dry due to entrance being out of water entrance being out of water bearing sand.bearing sand.zzIncorrect and correct Incorrect and correct positioning of galleries.positioning of galleries.German Tunnel SystemsGerman Tunnel SystemszzApproaches placed behind lines, hidden from enemy observation.Approaches placed behind lines, hidden from enemy observation.zzMultiple entrances separated by distance to prevent on barrage fMultiple entrances separated by distance to prevent on barrage from eliminating all rom eliminating all entrances.entrances.zzEntrances must be hardened if not hidden and protected from spliEntrances must be hardened if not hidden and protected from splinters and gas.nters and gas.zzDry rock = Inclined shafts, Wet rock = concrete or steel shafts.Dry rock = Inclined shafts, Wet rock = concrete or steel shafts.zzCover must be sufficient to prevent damage from artillery.Cover must be sufficient to prevent damage from artillery.zzListening posts placed at twice the listening distance.Listening posts placed at twice the listening distance.zzNumber of mines based on geologic and hydrologic conditions.Number of mines based on geologic and hydrologic conditions.CombresCombresHeight MinesHeight MineszzBegun in dry Begun in dry marl and water marl and water bearing iron bearing iron bearing bearing ooliticooliticlimestone. limestone. zzWater entered Water entered tunnels tunnels wherever wherever tunnels passed tunnels passed through through ooliticooliticlimestone layer.limestone layer.zzGeologists Geologists mapped section.mapped section.zzRecommended Recommended moving attack moving attack tunnels lower tunnels lower into marls into marls underlying underlying ooliticooliticlayer layer where it was where it was easier to tunnel.easier to tunnel.Water bearing siltsWater bearing silts and limestoneWater free silts and clayswith dolomitic and limestonebeds.Blast Craters FieldBlast CratersProposed Attack MineGeologic SectionProposed Mine through water bearing layerMine as Constructed in dry silty limestone bedsWytschaeteWytschaete--BogenBogenMinesMineszzEnglish used two English used two geologists to plan mines geologists to plan mines in the salient near in the salient near St.YvesSt.Yves. . zzEspecially complex Especially complex geology with several geology with several different Tertiary and different Tertiary and Quaternary formations Quaternary formations with separate water with separate water tables. tables. zzUsed shallower attack Used shallower attack tunnels to divert tunnels to divert German attention from German attention from deep tunnels.deep tunnels.zzEnglish fired 19 mines English fired 19 mines containing 423,000 kg containing 423,000 kg of explosives helping of explosives helping eliminate the eliminate the WytschaeteWytschaetesalient. salient. Water