Geologic Time ScalePrecambrian Minimal fossil recordEra, Period, EpochBased on major changes extinctions, mountain building events

Relative TimePrinciple of SuperpositionFossil EvidenceCross Cutting RelationshipsUnconformitiesAlterationFracture Termination

Siccar Point Unconformity

Angular Unconformity Santa Barbara

Cross-cutting relationship - dike

Smiths Map of England

Paleozoic (Old Life) Brachiopods, Trilobites, FishPeriods based on English GeologyCambrian for Latin WalesOrdovician and Silurian for ancient Welsh TribesDevonian for DevonCarboniferous for Coal Measures (also Mississippian and Pennsylvanian in US)Permian for Perm Basin in Ukraine

Mesozoic (Middle Life) Ammonites, DinosaursTriassic based on distinctive three-layer stratigraphy in southern GermanyJurassic based on Jura Mountains in France and SwitzerlandCretaceous (Latin for Chalk) based on chalk unit that forms Dovers cliffs

Cenozoic (Recent Life) Mammals, Modern marine fauna (foraminifera)Periods are Tertiary (before Ice Ages) and Quaternary (ice ages)Primary and secondary have been long replacesRocks of western Washington are Tertiary and Quaternary

Age of the EarthKelvin and a basis in heat flow (set at 20 million years)Problem of fitting all of evolution in this timeRutherford and the introduction radioactive decayAdded a head source, pushed ages back to 4.5 billion years

Absolute TimeBasis on radiometric dating (see Rahn chapter 1)Common dating tools14C, K-Ar, Rb-Sr,Uranium decay series

CEE 437Structural Geology World StressBrittle and Ductile DeformationFaults and JointsFolds

Representing a PlaneStrike and DipQuadrant Convention (N 60 E, 45 SE)360o Convention (120, 45)Right hand rule: dip 90o clockwise of strike)Pole trend and plungeDip vectordoes not discriminate strike of vertical planes

Brittle Versus Ductile BehaviorStrain Rate DependenceNon-elastic Deformation Mechanismsrecrystallizationlattice dislocationspressure solution and redeposition

World Stress Map

Brittle DeformationExtensile or ShearContinuum of Joints and FaultsFaults as Strain ConcentratorsInternal Structure of Faults

In Situ Stress MeasurementSeismic dataFirst motionsStress dropsHydraulic FracturingOvercoringBorehole Breakouts

Fault TypesNormal Extensile DeformationHanging Wall downHorsts and GrabensReverse Compressive DeformationHanging Wall upThrust FaultsStrike-slip Mostly transform faults

Fault NomenclatureHanging wall (overhead)Footwall (underfoot)GougeDamage ZoneCataclasiteMylonite

Normal Fault, Death Valley

http://darkwing.uoregon.edu/~millerm/slides.html

Normal Fault, Canyonlands

http://www.geo.cornell.edu/geology/classes/RWA/GS_326/photos/tf/DesertPk.jpg

Fault Gougehttp://darkwing.uoregon.edu/~millerm/slides.html

Sevier Thrust

Keystone Thrust, Nevadahttp://darkwing.uoregon.edu/~millerm/slides.html

Strike Slip Faults, Nevadahttp://darkwing.uoregon.edu/~millerm/slides.html

Strike-Slip, San Andreas Fault, Carrizo Plain

Engineering Concerns of FaultsPlanes of WeaknessSources of Seismic Hazard if ActiveSignificant Water CoursesSignificant as Groundwater Dams

FoldsAnticlineConcave down or oldest beds at coreSynclineConcave up or youngest beds at coreOverturned and Recumbent FoldsFold TermsHinge, Axis

Identifying Fold TypesAttitude of bedsPattern of beds on geologic mapsAnticline oldest at coreSyncline youngest at core

Engineering Concerns of FoldsMeans of Extrapolating Bed LocationsFracturing related to foldingFavorable or non-favorable orientations of beds to engineered structures or slopes

Ramp Fault, B.C.

Recumbent Foldshttp://darkwing.uoregon.edu/~millerm/slides.html

Fine-Scale Foldinghttp://darkwing.uoregon.edu/~millerm/slides.html