Term
| What does sorting measure in a sample? What factors determine sorting? |
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Definition
| Range of particle sizes in the deposit. calculate trask sorting coeff. |
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Term
| What determines grain shape? How is it measured? What are the basic grain shapes? |
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Definition
| CSF=c/sqrt(ab) where a b and c are the longest, intermediate, and shortest axis of the particle. Disks, spheroids, blades, rods. |
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Term
| What is grain roundness? What factors determine grain roundness? What does grain roundness tell you? |
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Definition
| Shape of corners on particle of sediment. the ratio of the average radius of curvature of the edges or corners to the radius of curvature of the maximum inscribed sphere. It can tell you how fluid moves thru deposit and intergranular fluid in the deposit. |
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Term
| What is porosity? What is permeability? |
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Definition
| Porosity is void space fraction. Premeability fluid flow thru pore network. |
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Term
| What is the relationship between porosity/permeability and grain size? Why? |
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Definition
| Perm is controlled by grain size and sorting. |
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Term
| What is the relationship between porosity/permeability and sorting? Why? |
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Definition
| Porosity is mostly b/c of sorting. Permeability controlled by grain size and sorting. |
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Term
| What is the range of depositional (original) porosity in sand? What factors influence depositional porosity? |
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Definition
| Extremely well to very poorly sorted. Median diameter and trask sorting. |
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Term
| What is the scientific field of Sedimentology? |
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Definition
| Study of production, transport, deposition, lithification of sediment. |
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Term
| hat is the scientific field of Stratigraphy? |
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Definition
| Classification, correlation, interp. of sed. roks. |
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Term
| Sedimentary rocks make up what fraction of Earth’s crust? |
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Definition
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Term
| Sedimentary rocks cover what fraction of Earth’s surface? |
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Definition
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Term
| What is the average and maximum vertical thickness of sedimentary rock sections on the continents? |
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Definition
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Term
| 40 % of exposed sedimentary rocks on the continents are younger than what age? |
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Definition
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Term
| Periods on the geologic time scale were original defined by what three types of stratigraphic events? |
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Definition
| Paleo: Extinctions, regional uncomformities caused by tectonics, geochem change from environment. |
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Term
| What are the three fundamental types of sedimentary rocks? Which two rock types are composed of particles that primary form within the depositional basin? Which rock type is primarily composed of particles derived from outside the depositional basin? |
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Definition
| Clastic, biochem, chem. Biochem and chem. Clastic. |
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Term
| What is the definition of the Trask Sorting Coefficient? |
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Definition
| So=sqrt(D25/D75) these are first and third quartile medians. |
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Term
| What are typical rates of horizontal motion for crustal plates? |
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Definition
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Term
| What are typical rates of vertical motion for crustal plates? |
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Definition
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Term
| What is basin subsidence? How is basin subsidence connected to net sediment deposition? |
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Definition
| It is what causes considerable thicknesses of sed deps to acc. Subsidence induces net depostion. |
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Term
| When does weathering occur? |
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Definition
| When some process breaks down and decomposes rocks. |
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Term
| What is the difference between weathering and erosion? |
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Definition
| Weathering is breakdown of rocks, erosion is the moevement of weathered material. |
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Term
| What is the difference between physical and chemical weathering? |
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Definition
| In physical there is no change in chem comp of weathered material. |
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Term
| What environmental factor has the greatest control on weathering? When does physical weathering dominate? Chemical weathering? |
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Definition
| Pressnce of water. When water is limited (arid, cold, high elevation) |
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Term
| Ultimately, what drives most erosion? |
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Definition
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Term
| What are the 3 basic products of weathering? |
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Definition
| Sediment, clay minerals, dissolved salts. |
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Term
| What are examples of physical weathering? Exactly, how does each cause physical weathering? |
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Definition
| Thermal stress, ice forst wedging, permafost, biogenic, abrasion by transported grains, exfoliation, salt growth, wetting/drying, metorite impact |
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Term
| What are examples of biogenic physical and chemical weathering? |
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Definition
| Roots, animal burrowing. Dissolution, hydrolysis, ox/red. |
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Term
| How does physical weathering occur with flowing water and air? |
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Definition
| Water can carry grains that abrade, wind can too. |
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Term
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Definition
| rocks that have been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals. |
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Term
| What attributes of rocks influence the type and rates of weathering? |
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Definition
| Rock mineralogy, zones of weakness, phys weathering can increase chem weathering by increasing surface area. |
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Term
| What is the role of fractures, joints and bedding planes in weathering? |
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Definition
| They are zones of weakness. |
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Term
| How does physical weathering promote chemical weathering? |
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Definition
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Term
| With respect to grain morphology, where does chemical weathering occur? |
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Definition
| Chemical weathering happens to minerals formed deep in interior which are not stable at surace. |
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Term
| What are the main products of chemical weathering? |
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Definition
| clay minerals and ions in solution |
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Term
| What are the primary controls on rates of chemical weathering? |
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Definition
| Where this is abundant water and temp. |
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Term
| What is the relative susceptibility to chemical weathering of the common minerals found at the Earth’s surface? |
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Definition
| Quartz and feldspar not weatherable, olivine plagiocase vulnerable. |
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Term
| What is the role of microbes in chemical weathering? |
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Definition
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Term
| What are the 3 basic chemical reactions that describe chemical weathering on Earth? |
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Definition
| hydrolysis, dissolution, ox/red |
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Term
| What is dissolution? What are the products? What minerals are most susceptible to this form of chemical weathering? |
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Definition
| Cations and anions in solution transported away leaving spaces in rock. Limetone, |
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Term
| What is the chemical formula for carbonic acid? How is it formed? |
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Definition
| CO2 from air is dissolved in rainwater. H2CO3. |
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Term
| What is the average pH of rain water? |
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Definition
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Term
| What is the basic chemical process of hydrolysis? What minerals are most susceptible? Weathering product? |
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Definition
| Feldspar reacts with free hydrogen ions in H2O to form secondary mineral (kaolinite and additonal ions). |
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Term
| What is the most common mineral on the Earth’s surface? |
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Definition
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|
Term
| What is reduction? What minerals are most susceptible? |
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Definition
| Gain of e- from an element. Fe 2+ |
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Term
| What is oxidation? What minerals are most susceptible? |
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Definition
| Loss of an e-.Iron or mn containing minerals such as pyroxene |
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Term
| What are the weathering products of these common minerals: Quartz, Feldspar, Amphibole, Pyroxene, Biotite, Muscovite? |
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Definition
| quartz grains, clay minerals, (clay minerals limonite hematite), |
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Term
| What happens to the solution phase (ions) of weathering? |
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Definition
| The ions are transported away leaving space in the rock |
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Term
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Definition
| surface material that includes an organic component due to weathering |
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Term
| What are the controls on soil development? |
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Definition
| climate, topography, precursor material |
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Term
| What is the profile of a soil (i.e., layers)? |
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Definition
| organic layer, zone of leaching, zone of accumulation, c horizon |
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Term
| How would you recognize a paleosol in the rock record? |
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Definition
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Term
| What are the roles of flowing water, air or ice in shaping the Earth’s surface? |
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Definition
| all these things transport sediment around |
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Term
| How are sediment-gravity flows different from fluid-gravity flows? |
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Definition
| Sediment gravity flows contain a lot more sediment and have greater viscosity and finite strength that must be exceeded for flow to occur. |
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Term
| What is a fluid? What is different about the fluids water and air? |
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Definition
| it has no strength. water has a tighter molecule config. |
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Term
| What is density? What are the densities of water, wind and ice? Why does it matter in terms of sediment transport? |
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Definition
| m/v. 1, 10^3, 10^3 kg/m^3. it's used to calculate kinematic visocisty. |
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Term
| What is dynamic viscosity? What does it measure? What is kinematic viscosity? |
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Definition
| measure of the internal friction of a fluid. kv is dv divided by density. |
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Term
| What is the Froude Number? What is tranquil flow, shooting flow, and a hydraulic jump? |
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Definition
| ratio btwn inertial and grav forces, applicable to all flows having a fluid interface. fr<1 waves can propogate up and down. fr>1 wave cannot go up. fr=1, up waves stuck here |
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|
Term
| What is the Reynolds Number? |
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Definition
| measure of the ratio of inertial forces to viscous forces |
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Term
| What is the difference between laminar and turbulent flow? How/why can these be characterized by the Reynolds Number? |
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Definition
| stable or unstable to small disturbances. If Re>>1, turbulent, Re<1 stable. |
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|
Term
| What do flow pathlines look like in laminar and turbulent flow? |
|
Definition
|
|
Term
| What are the forces acting upon grains subject to flowing fluid? |
|
Definition
|
|
Term
| If we know the forces acting upon grains with fluid flow, why don’t we just directly calculate sediment transport? |
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Definition
| You need extra forces beyond just lift and drag forces. You have to figure it out experiementally. |
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Term
| What is the Shields Diagram? What does it show? |
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Definition
| graph that shows values for critical shear stress. |
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Term
| What is boundary shear stress? What is the critical shear stress to move sediment? How are these related to initiate sediment movement? |
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Definition
| characterizes near bed conditons for sediment transport. css is associated with initial motion of a significant number of particles. |
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Term
| How is the boundary shear stress related to the mean flow velocity? |
|
Definition
| p*C_d*u=Tb where u is mfv and Tb is bss |
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Term
| What is the grain fall or settling velocity? How is it determined? When does grain suspension occur? |
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Definition
| Maximum velocity of the grain, Fr=Fg, when |
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|
Term
| Simplifications have been made to make it practical to calculate sediment transport for flowing fluids. What are the key connections that have been made? |
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Definition
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|
Term
| Under what conditions of boundary shear stress and setting velocity does transport occur as pure bedload? |
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Definition
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|
Term
| Under what condition of settling velocity does suspension occur? |
|
Definition
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|
Term
| What are the modes of grain movement? What are the components of bedload? |
|
Definition
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|
Term
| In typical suspended transport, where are most of the grains located? |
|
Definition
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|
Term
| What concentration of suspended sediment might you expect in a flowing river? |
|
Definition
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|
Term
| How is total sediment discharge calculated? |
|
Definition
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|
Term
| What are examples of sediment-gravity flows? How are grain concentrations different in sediment-gravity flows than in fluid-gravity flows? |
|
Definition
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|
Term
| What is the sequence of bed configurations at low Froude numbers? |
|
Definition
| lower plane bed, typical ripple pattern, dunes with ripples superposed, dunes, washed out dunes/ transition, upper plane bed |
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|
Term
| What is the sequence of bed configurations at high Froude numbers? |
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Definition
| standing waves, incipient breaking and movin upstream, breaking antidune pool |
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|
Term
| Be able to sketch the phases of bedforms as a function of grain size and mean flow velocity. |
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Definition
| Antidunes: highest flow velocity for all sizes. Upper plate: small, high. Dune med-large, high, ripples low to med, low to med. no movement big particle, slow v. |
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Term
| What is the sequence of bedforms with increasing flow speed in coarse silt to very fine sand? Fine sand to medium sand? Coarse sand to gravel? |
|
Definition
ripples>UPB>antidunes
ripples>dunes>UPB>antidunes
LPB>dunes>UPB>antidunes |
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|
Term
| Why is it now thought that ripples and dunes in water form a continuum? |
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Definition
| they form an upward trend in size |
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|
Term
| Are there bedforms with lower plane bed? |
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Definition
| not really they are planar surfaces, some gravelly streaks. |
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|
Term
| What are the features of lower plane bed? How do the grains move? Resultant stratification? What is imbrication? Why is finer sand common among gravel in lower plane bed? What is surface armoring? How does it form? |
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Definition
| Coarse material protects sand from being weathered. Water flows up and over the imbricated rocks with minimal effort. |
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Term
| Be able to label morphological parts of ripples/dunes (e.g., stoss, crest,…) |
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Definition
| The key thing to know is that the upstream side is the stoss and the lee face is on the other side. (remember those diagrams). The brink point is the edge, crest is highest point of topography. Lowest pt of topography is trough. Dist. From trough to trough is the wavelength |
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Term
| What is the angle of repose? What is a typical angle? |
|
Definition
| steepest angle of descent or dip of the slope relative to the horizontal plane when material on the slope face is on the verge of sliding. |
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|
Term
| What is a slipface? What stratification types characterize a slipface in subaqueous ripples and dunes? |
|
Definition
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|
Term
| What part of the transport load typically makes up ripples? How is ripple height impacted by water depth? What is ripple index? What are typical values for subaqueous ripples? |
|
Definition
|
|
Term
| What part of the transport load typically makes up dunes? Are is dune height impacted by water depth? How constant is interdune scour depth in subaqueous dunes? |
|
Definition
|
|
Term
| What is a sand bar? How is it different from a sand dune? |
|
Definition
|
|
Term
| How is a set of cross-strata generated? What is the accumulation surface? What is bedform climb? How is it calculated? What is a foreset? Bottomset? Topset? |
|
Definition
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