Geos 240 Study Guide Exam 2 – Winter 2015
Covers Chapters 4-8.4 in Miall and labs 4-6 through p 118 and fluid transport
Chapter 4: Basic Physical Sedimentology (hint some of these may show up on the
rock practicum!)
a) Sedimentary textures: grain size, sorting, grading, imbrication, porosity, cements
b) Depositional sedimentary structures: bedding, cross bedding ripple marks, varves,
c) Erosional structures: channels, intraformational breccias, hardgrounds
d) Soft sediment deformational structures: lode casts, fluid escape, flame structures
ball and pillow, injection, clastic dykes, dish and pillar,
e) Dessication: mudcracks, salt casts
Fossil structures: impressions, replacive molds and casts
f) Ichnofossils: traces of feeding behaviour, oxygen levels, substrate types and water
depths
g) Drawing and interpreting stratigraphic cross sections and 1-dimensional strip
logs.
Chapter 5: Principles of Stratigraphy
a) Lithologies: siliciclastic, mixed, carbonate, chert, massive sulphide, evaporate,
coal
b) Lithostratigraphy: formations, members, tongues, beds, facies,
c) Facies equivalence and diachroneity of lithostratigraphic formations
d) Event or marker beds and time lines versus facies
e) Unconformity bounded stratigraphic sequences (Sloss, Vail) and allostratigraphy:
regional flooding surfaces, episodic processes; orogeny, epeirogeny, global sea level
cycles
f) Biostratigraphy: faunal succession, fossil types and their environmental and time
significance, planktos, nektos, benthos, FADs and LADs, Range zones, index fossils,
disaster species, relationship of biostratigraphy to paleogrography, Tethyan versus
Boreal assemblages, microfossils versus macrofossils and applications, dominant
marine microfossil types with time (radiolarian, diatoms, foraminifera, coccoliths,
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dinoflagellates), terrestrial spores and pollen), important macrofossil types, main
invertebrate types, major groups of vertebrates with time, biozones versus
chronozones, Flaws with the fossil record
g) IUGS and IUGP international stratigraphic time scale and the significance of
replacing classical stratigraphic units with golden spike sections.
h) How is absolute radiometric chronology related to real stratigraphic sequences?
i) Other correlation proxies for geological time and where they apply:
magnetostratigraphy, stable isotope stratigraphy
j) The changing Geological Time Scale: what has changed and what is likely to
change in the future to how we delineate geological time.
Chapter 6: Facies Analysis
a) The facies concept and many kinds of facies subdivisions: lithofacies, biofacies,
ichnofacies, seismic facies, organic facies, maturation facies, alteration facies
b) Descriptive (observational) versus interpretive facies schemes
c) Facies architecture and bounding surfaces
d) Facies associations and Walther’s Law
e) Strip log profiles and log shape analysis
f) Facies models, facies schemes and why we need them to make our observations
g) Uniformitarianism and problems applying this to stratigraphy as well as to
modern ongoing processes: continual versus episodic sedimentation, epochal data
and one time observations, captured versus missing time, non-uniformitarian
deposits and the geological record.
Chapter 7: Geophysical Fluids and Sediment Transport
a) Fluids and fluid properties: air, water, ice; density, viscosity, velocity,
momentum; fluid and particle inertial forces
b) Laminar versus turbulent flow and Reynolds number, streamlines, continuity,
conservation of mass, energy and momentum during flow
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where:
vs is the mean fluid velocity in ms-1
L is the characteristic length in m
μ is the (absolute) dynamic fluid viscosity in Nsm-2 or Pa·s
ν is the kinematic fluid viscosity, defined as ν = μ/ρ, in m2s-1
ρ is the density of the fluid in kgm-3
Basically at high values of the Reynolds number in the 1000’s or higher inertial
forces dominate and flow is turbulent (smoke in the wind). At low values of
Reynolds number 0-10 viscous forces dominate and flow is laminar (syrup across a
plate), L depends on the geometry of the flow regime (dimension of channel, depth
of water etc).
c) 3 places and modes of particles transport in fluids: suspension, saltation and
traction
d) Velocity gradients, fastest away from bed or wall of channel, slow near particle
surfaces; eddies and vorticity
e) The Hjulstrom diagram and entrainment versus deposition of unconsolidated
sediments, threshold velocities, particle size versus sediment transport and sediment
erosion
f) Bedforms and the turbulent bondary layer, separation eddies
g) Subaqueous mass flows, gravity and turbidity currents
h) The flow regime concept, Froude number F= U/(g)1/2 D and bedform phase
diagrams; lower (ripples to cross beds), transitional (washed out and humpback
dunes) and upper (upper plane bed, anti-dunes or chute and pool) flow regimes,
flow direction, currents, waves and equilibrium bedforms. At larger depths and
lower flow velocities, dunes can be linear or 2D, at shallower depths and faster
velocieties dunes are linguoid or 3D). Due to properties of water and density
contrasts to sediment ripples are less than 4 cm and dunes are bigger than 8 cm
without much in between due to eddies and turbulence interactions between flow
regime and bed.
h) Differences between sand and gravel bedforms, grading and imbrication, single
episode deposition versus residual lag sediments
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i) Different types of cross beds and their origin: trough cross beds, flaser, bundling,
channelized flow, storms and reversing tidal currents
j) Hummocky cross stratification, combined flow, geostrophic currents
k) Eolian bedforms, sediments and desert environments: dune types, wind ripples,
grain fall, grain flow, deflation surfaces, ventifacts. How do subaerial dunes differ
from subaqueous ones and why? Why are the oldest Eolian sediments 1.8 Ga?
l) Turbidity deposits, flow types and sediment versus fluid dominated flow and
transport evolution in a down flow direction.
Chapter 8 – Depositional Environments
I) Clastic systems
a) Fluvial – River, gradients, sediment supply, flow variation and 4 regimes:
braided, meandering, anastamosing, straight with decreasing gradient and caliber
of sediments
b) Eolian- ergs, bounding surfaces, deflation, dune migration, the roles of water
table position, changing sediment supply and cementation
c) Lacustrine- laminates, organics, varves, and dropstones. Seasonal sedimentation
and long term climatic records.
d) Nearshore wave and tide dominated coastal systems: back beach dunes, beaches,
barrier bars, lagoons, tidal inlets, tidal deltas, flood, ebb, sediment supply and
longshore drift.
e) The role of transgressive versus regressive cycles on depositional systems. Can
you distinguish between transgression, waning sediment supply, sediment
compaction, and subsidence? What else do you need to know. Can we just call this
transgressive versus regressive systems?
f) How does transgression or one of those indistinguishable processes cause
ravinement and what would this look like in cross section. How would time lines
appear on this diagram?
g) Deltas: 3 dominant processes: river flow (sediment supply, progradation, infil,
avulsion), wave energy (shoreface armouring by beaches or bars, waning river flow,
loss of water from deglaciation or agriculture/industry) and tidal flow/currents
(shallow sea or high tidal ranges cause reversing currents to fill and empty tidal
inlets, building tidally controlled channel located sand bars. Mississippi is a river
dominated system, Rhone is wave dominated (ah the rough end of the Sea!), Ganges
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is tidally dominated due to outbuilding and infilling controlling tidal flow with long
inlets, and India in the way. Niger and Fraser are pretty intermediate type deltas.
h) Avulsion nodes and distributary abandonment during waning floods or storm
surges.
i) Deltaic profiles: topset sands and silts, foreset (prodelta sand clinoforms),
foredeep (bottomset muds). Channel position and lateral and long system facies
changes near channel mouths. Sedimentary models for estuaries and placing
environments along the fraser.
Test Format: Similar to midterm 1 with matching terms and definitions, multiple
guess and T/F plus 4 essays.
Sample Vocabulary:
Aggradation
Alloformation
Alluvial fan
Alluvial plain
Ammonite
Antidune
Arenite
Autogenic
Avulsion
Barchan
Base level
Ball and pillow
Barrier bar
Base level
Beach
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Bedform
Bedload
Bell shaped
Benthic
Bingham plastic
Bio-erosion
Biofacies
Bioherm
Biostratigraphy
Bioturbation
Biozone
Birdsfoot
Boreal
Bouma sequence
Bounding surface
Brachiopod
Breccia
Channel
Chemical sediment
Chron (magnetic)
Chute and pool
Clastic dyke
Climbing ripple
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Clinoform
Coarsening upward
Coccolith
Condensed section
Continental shelf
Conodont
Crevasse splay
Cut bank
Debris flow
Deflation
Delta
Dessication
Dewatering
Diachronous
Diastem
Diatom
Dinoflagellate
Dish and pillar
Distributary
Drape
Dunes (2-D & 3D)
Eolian
Erg
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Estuary
Eustasy
Event stratigraphy
Facies
Fining upward
First appearance datum
Flame structure
Flaser bedding
Floodplain
Flow regime
Flute
Fluvial
Foraminifera
Foreset
Formation
Froude number
Funnel shaped
Fusilinid
Geostrophic current
Golden spike
Graded bedding
Gravity flows
Group
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Heavy minerals
Hiatus
Hjulstrom diagram
Hummocky
Humpbacked
Ichnofacies
Imbrication
In phase
Isopach
Lag deposit
Lagoon
Laminae
Last appearance datum
Levee
Lithology
Load structure
Loess
Log shape
Magnetozone
Map unit
Marginal sea
Marsh
Member
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Nektonic
Newtonian fluid/flow
Pelagic
Placer
Plane bed
Planktonic
Point bar
Ravinement
Regression (forced and normal)
Ripple mark
Separation eddy
Set up
Sequence (parasequence)
Shoestring sand
Sole mark
Stratotype
Stone stripe
Storm shelf
Super surface
Tethyan
Tidal
Tool mark
Trace fossil
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Traction current
Transgressive
Trilobite
Trough cross bedding
Turbidity current
Regressive
Uniformitarian
Ventifact
Walther’s Law
Washover fan
Wave dominated
Sample Essay Topics:
1) Describe the evolution of clastic sediments, downsystem or with time on: 2
ternary plots: QFL and Q/F+L/M, contrasting the trends for a convergent
continental margin and an island arc.
2) Given a particular strip log and some brief descriptive notes: post likely locations
for a list of additional: lithologies, sedimentary structures, fossils or ichnofossils and
discuss in brevis, your logic for these choices. Eg. I might give you a succession with
all or parts of a Bouma sequence, a braided stream, a storm shelf to fill in plausible
details.
3) Why is straphigraphy divided into allosequences or systems? Discuss the causes
of major unconformity bounded successions and give an example.
4) How are the principles of biostratigraphy and chronostratigraphy applied to
interpret absolute ages on fossil zones?
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5) Illustrate and or discuss how fossils are used for chronology in biostratigraphy.
What does this have to do with extinctions and adaptive radiation? Discuss the
relative merits of planktic versus benthic organisms and explain the criteria needed
for an ideal marker fossil.
6) Explain the different sorts of information used and varying precision afforded in
defining the geological time scale. For instance compare and contrast how and what
we know about the Cretaceous, the Cambrian and the Archean.
7) How do fluid density, viscosity and flow regime (velocity/depth) regulate laminar
versus turbulent flow and determine the types of sediments being transported and
deposited? Compare and contrast deposits resulting from both kinds of flow,
including the relative role of grains and fluid in each setting.
8) Draw and annotate the Hjulström diagram and explain to a poor feckless marine
pipeline engineer why he should know about this.
9) Draw and discuss an orderly progression of bedforms you might expect for
progressive changes from lower through transitional and upper flow regime.
10) Discuss the physical causes and sedimentalogical consequences of geostrophic
currents.
11) Illustrate in a pair of contrasting cross sections and explain how could you might
be able to distinguish between a progradational deltaic sequence from a coastline
that experienced a single episode of transgression.
12) Discuss and illustrate the various sorts of physical information that can be
obtained from detailed analyses of crossbedded sediments.
13) Discuss ergs, their environmental causes, typical bedforms and styles of
sediment transport and the controls on deposition. Explain how other facies might
intervene or play a role in the sedimentary record of these settings.
14) Draw a cartoon and or discuss the characteristic sub-environments, sediment
types, geomorphic features and physical controls on flow that influence shallow
water, near shore coastline facies?
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15) Deltaic morphology, sand isopach patterns and architecture vary according to 3
competing groups of processes. Discuss these 3 processes (river, tidal, wave) and
give real world examples of deltas that fit the overall model.
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