General & Field Geology
17%of exam
Mineralogy, Petrology & Geochemistry
5-12%of exam
Sedimentology, Stratigraphy & Paleontology
5-11%of exam
Geomorphology, Surficial & Quaternary
8-14%of exam
Structure, Tectonics & Seismology
9-12%of exam
Hydrogeology
13-22%of exam
Engineering Geology
12-18%of exam
Economic Geology & Energy
9-16%of exam
Quick Facts
- FG Exam
- 140 MCQ, 4 hours
- PG Exam
- 110 MCQ, 4 hours
- Pass
- Scaled score 70
- Domains
- 8 content areas
- Format
- Computer-based (Prometric)
- Fee
- $200 FG + $250 PG
- Seat fee
- $75 per part
- Eligibility
- State board approval
Geologic Periods
Camels Often Sit Down Carefully Perhaps Their Joints Creak
Cambrian, OrdovicianSilurian, DevonianCarboniferous, PermianTriassic, JurassicCretaceous
Date the Rocks
- Order undeformed beds→Superposition(Relative)
- Dike cuts unit→Cross-cutting(Younger cutter)
- Fragment in rock→Inclusions(Clast older)
- Correlate distant strata→Faunal succession
- Need numeric age→Radiometric dating(Absolute)
Relative Dating Principles
- Superposition
- Lower beds are older
- Original horizontality
- Layers deposit flat
- Cross-cutting
- Cutter is younger
- Inclusions
- Fragments predate host
- Faunal succession
- Fossils in fixed order
- Uniformitarianism
- Present interprets past
Time + Unconformities
- Time hierarchy
- Eon, era, period, epoch
- Phanerozoic
- Paleozoic, Mesozoic, Cenozoic
- Precambrian
- Hadean, Archean, Proterozoic
- Disconformity
- Gap, parallel beds
- Angular unconformity
- Tilted beds below
- Nonconformity
- Strata over basement
- Paraconformity
- Hidden time gap
Bowen Discontinuous Series
Olivine → Pyroxene → Amphibole → Biotite
Olivine: highest tempPyroxene: single chainAmphibole: double chainBiotite: sheet micaMafic weathers first
Mineral ID Properties
- Mohs hardness
- 1 talc to 10 diamond
- Luster
- Metallic or nonmetallic
- Cleavage
- Breaks along planes
- Fracture
- Breaks irregularly
- Streak
- Powder color
- Specific gravity
- Density vs water
- Crystal habit
- Characteristic crystal shape
Mohs Hardness 1-10
Toronto Girls Can Flirt And Only Quit To Chase Dwarves
1 Talc, 2 Gypsum3 Calcite, 4 Fluorite5 Apatite, 6 Orthoclase7 Quartz, 8 Topaz9 Corundum, 10 Diamond
Silicates + Rock Cycle
- Nesosilicates
- Isolated tetrahedra (olivine)
- Inosilicates
- Chains: pyroxene, amphibole
- Phyllosilicates
- Sheets: micas, clays
- Tectosilicates
- Frameworks: quartz, feldspar
- Fractional crystallization
- Melt evolves felsic
- Index minerals
- Chlorite to sillimanite grade
- Foliation
- Aligned metamorphic minerals
Deposition + Facies
- Walther's law
- Adjacent facies stack vertically
- Bouma sequence
- Turbidite Ta to Te
- Cross-bedding
- Records current direction
- Graded bedding
- Coarse fines upward
- Transgression
- Sea level rises
- Regression
- Sea level falls
Stratigraphy + Fossils
- Index fossil
- Widespread, short-lived
- Biostratigraphy
- Correlate by fossils
- Lithostratigraphy
- Correlate by rock
- Sequence boundary
- Sea-level fall surface
- Maximum flooding surface
- Peak transgression level
- Facies model
- Predictive depositional reconstruction
Weathering vs Erosion
Weathering
- Breaks in place
- Physical or chemical
- No transport
Erosion
- Removes material
- Water/wind/ice
- Transports away
Break vs transport
Fluvial + Slopes
- Strahler order
- Stream ranking system
- Drainage density
- Channel length per area
- Cut bank
- Outer bend erosion
- Point bar
- Inner bend deposition
- Angle of repose
- 30-35° dry sand
- Base level
- Lowest erosion limit
Glacial + Weathering
- Till
- Unsorted ice deposit
- Stratified drift
- Sorted meltwater deposit
- Moraine
- Glacial debris ridge
- Loess
- Wind-blown silt
- Solifluction
- Saturated soil creep
- Karst
- Dissolved carbonate terrain
- Chemical weathering
- Dissolution, oxidation, hydrolysis
Fault Sense
Normal drops, Reverse raises, Strike-slip slides
Normal: extensionReverse: compressionStrike-slip: shear
Stress vs Strain
Stress
- Force per area
- The cause
- Compression/tension/shear
Strain
- Deformation result
- The effect
- Length/shape/volume
Cause vs effect
Identify the Fault
- Hanging wall drops→Normal fault(Extension)
- Hanging wall rises→Reverse fault(Compression)
- Low-angle reverse→Thrust fault(Shortening)
- Horizontal offset→Strike-slip fault(Shear)
- Fracture, no offset→Joint(Tension)
Stress, Faults, Folds
- Strike
- Compass bearing of bed
- Dip
- Steepest slope angle
- Normal fault
- Hanging wall drops
- Reverse fault
- Hanging wall rises
- Thrust fault
- Low-angle reverse fault
- Strike-slip fault
- Horizontal shear offset
- Anticline
- Fold arches upward
- Syncline
- Fold troughs downward
Anticline vs Syncline
Anticline
- Arches upward
- Oldest in core
- Convex up
Syncline
- Troughs downward
- Youngest in core
- Concave up
Old vs young core
Deformation + Tectonics
- Stress
- Force per area
- Strain
- Resulting deformation
- Brittle
- Fractures at shallow depth
- Ductile
- Flows at high P-T
- Divergent
- Plates spread apart
- Convergent
- Plates collide, subduct
- Slab pull
- Dominant plate driver
Darcy's Law
Flow = Conductivity × Area × Gradient
Q: dischargeK: conductivityA: areadh/dl: gradient
Confined vs Unconfined
Confined
- Bounded by aquitards
- Under pressure
- Small storativity
Unconfined
- Free water table
- Dewaters pores
- Large specific yield
Pressure vs water table
Groundwater Tool Picker
- Estimate flow rate→Darcy's law
- Aquifer-scale yield→Transmissivity
- Water that drains→Specific yield
- Confined storage→Storativity
- Drawdown over time→Theis solution
- Steady-state well→Thiem equation
- Coastal salt wedge→Ghyben-Herzberg
Darcy + Aquifer Properties
- Darcy's law
- Q = -K A dh/dl
- Hydraulic conductivity
- K of medium
- Transmissivity
- K times thickness
- Hydraulic gradient
- Head change per length
- Porosity
- Void volume fraction
- Specific yield
- Water that drains
- Specific retention
- Water held back
Conductivity vs Transmissivity
Conductivity K
- Property of medium
- Length per time
- Compare lithologies
Transmissivity T
- K times thickness
- Whole aquifer
- Well-yield estimates
Medium vs aquifer
Wells + Groundwater
- Confined aquifer
- Bounded, under pressure
- Unconfined aquifer
- Free water table
- Storativity
- Water per head change
- Cone of depression
- Drawdown around well
- Theis solution
- Transient drawdown analysis
- Ghyben-Herzberg
- Fresh-salt interface ratio
- Retardation factor
- Sorption slows contaminant
Yield vs Retention
Specific yield
- Drains by gravity
- High in sand
- Usable storage
Specific retention
- Held by capillarity
- High in clay
- Not recoverable
Drains vs held
Slope Failure Mode
- Curved surface, soil→Rotational slump
- Weak bedding plane→Planar slide
- Two joint sets→Wedge failure
- Steep inward joints→Toppling
- Saturated loose sand→Liquefaction
- Slow downslope movement→Creep
Soil + Rock Mechanics
- Effective stress
- Total minus pore pressure
- Mohr-Coulomb
- Cohesion plus friction strength
- Friction angle
- Grain shear resistance
- Atterberg limits
- Soil consistency states
- SPT N-value
- Standard blow count
- RQD
- Rock quality designation
- Factor of safety
- Resisting over driving
Hazards + Slope Failures
- Liquefaction
- Saturated sand loses strength
- Rotational slump
- Curved slip surface
- Planar failure
- Slide on plane
- Wedge failure
- Intersecting joint sets
- Toppling
- Steep joints overturn
- Rock bolt
- Passive tunnel support
- RMR / Q-system
- Rock mass rating
Resource vs Reserve
Resource
- Potentially economic
- Measured/indicated/inferred
- May not mine
Reserve
- Economically mineable
- Proven/probable
- Price-dependent
Potential vs economic
Ore Deposits
- Porphyry copper
- Low-grade disseminated sulfides
- Magmatic segregation
- Settled dense minerals
- SEDEX
- Sedimentary brine sulfides
- VMS
- Volcanic massive sulfides
- Placer
- Water-concentrated heavy grains
- Skarn
- Contact metasomatic ore
- Hydrothermal vein
- Hot-fluid mineral fill
Energy + Mining
- Resource
- Potentially economic material
- Reserve
- Economically mineable part
- Source rock
- Generates hydrocarbons
- Reservoir rock
- Porous, permeable store
- Trap and seal
- Holds migrating hydrocarbons
- Acid mine drainage
- Sulfide oxidation acid
- Reclamation
- Restore mined land
Common Traps
Stress vs Strain
Stress is force/area ≠ Strain is deformation
Conductivity vs Transmissivity
K describes medium ≠ T describes aquifer
Yield vs Retention
Yield drains freely ≠ Retention held tight
Weathering vs Erosion
Weathering breaks down ≠ Erosion carries away
Resource vs Reserve
Resource is potential ≠ Reserve is economic
Confined vs Unconfined
Confined under pressure ≠ Unconfined water table
Till vs Stratified Drift
Till unsorted, ice ≠ Drift sorted, meltwater
Last Minute
- 1.FG: 140 questions, 4 hours
- 2.PG: 110 questions, 4 hours
- 3.Passing score is 70 scaled
- 4.Eight content domains total
- 5.Hydrogeology dominates the PG exam
- 6.Superposition: older beds below
- 7.Bowen: mafic crystallizes first
- 8.Darcy: flow needs gradient
- 9.Effective stress = total − pore
- 10.Normal drops; reverse raises
- 11.Resource potential; reserve economic
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