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237 Cards in this Set
- Front
- Back
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What is the apparent dip of a bed? |
Apparent dip of a bed or plane is the inclination of that bed or plane in a direction not perpendicular to strike. |
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What is a fold line and how is it used? |
The fold line is a hinge line along which a vertical cross section may be constructed and then flattened out to a horizontal or map view. It is used to represent the subsurface along any given line in a map view. It need not be perpendicular to strike. |
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What is the angle and side relationships for the sin equation? |
Sin θ = opposite side / hypotenuse |
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What is the angle and side relationships for the tangent equation? |
Tan θ = opposite side / adjacent side |
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If an attitude is given as 35°, S25°E, what does that mean? |
The attitude 35°, S25°E, if given as a plane, represents a dip of 35° in the S25°E direction. This would translate to a strike of N65°E (or 90° away), and dip of 35°S. The Board wants to see answers in terms of strike and dip with respect to the two North quadrants. The attitude 35°, S25°E, if given as an apparent dip value or the bearing and plunge of a line, represents a line plunging 35° in the direction of S25°E. Apparent dip is given in these terms to represent the apparent dip angle in a given direction. |
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What is the general form of the thickness equation and why wouldn't you want to use it? |
thickness (t) = outcrop width ⊥ strike (w) sin [dip (δ), slope (σ)]
Generally it is easier to solve a thickness problem graphically because you need to draw a diagram to scale anyway to get the slope angle (σ) and the perpendicular outcrop width (w). |
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If you have a flat surface and an outcrop width that is not perpendicular to strike, what equation would you use to calculate the thickness of the unit? |
t = l sin β sin δ
l = traverse distance across the outcrop β = ∠ between strike and apparent dip direction δ = dip |
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What is the general equation for calculating the apparent dip of a bed and when can't this equation be used? What order methods can be used as an alternative? |
tan α = tan δ sin β α = apparent dip δ = dip β = (∠ between strike and apparent dip direction)
This equation can't be used for solving true strike and dip from two apparent dips. In order to solve a problem involving two apparent dips you must either solve graphically or using the stereonet. The stereonet solution is much simpler and less time consuming. |
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What defines an Index Fossil? |
An index fossil identifies and dates the strata in which it is found. It combines a wide geographic range with a narrow stratigraphic occurrence. |
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What is net slip and where is it measured? |
Net slip is the distance between two formerly adjacent points on either side of a fault, measured on the fault surface (in the plane of the fault). |
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What is an unconformity? |
An unconformity is a gap in the geologic record; an interruption in the depositional sequence that implies uplift and erosion have removed part of the geologic record or non-deposition has occurred. |
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What is the "Rule of V's"? |
The outcrop of a formation as it crosses a valley forms a V shape (as viewed on a map). The V points in the direction that the formation underlies the valley. |
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What is a type locality? |
A type locality is the place where a geologic feature (such as a fossil species or geologic formation or member) was first recognized and described. It contains the type section. |
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Define type section. |
Type section is the originally described straigraphic unit to which other parts of the unit in other locations may be compared. It is preferable to describe they location where the unit attains it's maximum thickness and where the top and bottom of the unit are exposed. |
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How does a reverse fault differ from a normal fault? How is it the same? |
A normal fault is a dip-slip fault in which the hanging wall has moved down relative to the foot wall. A reverse fault is a dip-slip fault in which the hanging wall has moved up relative to the foot wall. Both normal and reverse faults have a dip between 45° and 90°. |
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What is the Law of Initial Horizontality? |
The Law of Initial Horizontality assumes that the sequence of layers was deposited horizontally or early so. The oldest layer is therefore on the bottom and the youngest layer is on top. In dissected typography, the youngest layer will form hill tops. |
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What is the Law of Superposition? |
The Law of Superposition states that the oldest layer is on the bottom and the youngest layer is on the top. This assumes that the layers have not been overturned during deformation. If the beds are overturned or vertical, the stratigraphic succession can't be determined unless the absolute ages of the units are known. This law applies to any layered rock sequence such a sedimentary units or extrusive igneous rocks. |
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How are cross-cutting relationships used to determine relative ages? |
If cross-cutting relationships exist, the feature that is cut is older than the feature that cuts across it. Rocks may be cut by intrusion, faulting, unconformities, or replacement minerals. |
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What type of V will a vertical bed display on a map? |
A vertical bed will have no V. A vertical bed crosses all variations of topography with a straight line. This is also true of any vertical structural feature such as a fault. |
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What is casing? |
A heavy metal pipe lowered into a borehole and cemented in place to prevent cave-in, loss of drilling fluid, and unwanted fluids from entering the borehole. |
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What would cause a repetition or omission of units in cross-section? |
Repetition or omission of units in cross-section may be caused by faulting. In general, if the fault is a reverse fault there will be a repetition of beds and if the fault is a normal fault the beds maybe apparently missing. |
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What should be included on a complete geologic map? |
A complete geologic map includes a scale, north arrow, geologic symbols, and explanation. The explanation must include all symbols either originally on the map or added (including contacts, structure symbols, streams, cross-sections) and a stratigraphic column depicting all units shown on the map and placing them from the oldest units at the bottom to the youngest at the top. If available, the lithology, thickness and names of the units should also be shown. |
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What types of geomorphic features are diagnostic of faulting? |
Geomorphic features indicative of faulting include sag ponds, offset ridges, triangular facets, fault scarps, aligned springs, offset streams, and scarplets (especially when several other features are present). |
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What type of features are indicative of faulting but often are not extensive enough to be mapped? |
Slickensides, grooving, drag, gouge, or mylonite are indicative of faulting but are not always present. |
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What is the sequence of minerals that form in the process of fractional crystallization of a magma and what is the sequence called? |
Bowen's Reaction Series Discontinuous Continuous Olivine Anorthite Mg pyroxene Bytownite Mg-Ca pyroxene Labradorite Amphibole Andesine Biotite Oligoclase Albite K feldspar Muscovite Quartz
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What is a transgressive sequence? |
Transgression is the advance of the sea onto land. A transgression is represented by sandstone (or shallow water deposits) overlain by shale which in turn is overlain by limestone (a deeper water deposit). |
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What type of environment are you likely to find dolomite and why? |
Dolomite is precipitated directly from waters and highly saline tidal flats. Saline water in the poor space is in rich in magnesium ions due to evaporation. Some of the excess magnesium is exchanged for calcium in calcium carbonate, converting it to a dolomite. The process is a diagenetic process. |
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What is the process by which peat becomes coal and what causes the various grades of coal? |
Peat is formed when decaying vegetation does not have enough oxygen. Plant fossils indicate peat is formed in fresh-water swamps. After burial the chemical transformation peat becomes lignite. More time, deeper burial, and higher temperatures convert lignite to bituminous and ultimately and anthracite coal. |
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How are evaporites formed? |
Evaporites form by evaporation of lake water in arid regions, or from marine waters and restricted basins where the rate of evaporation balances the recharge of the basin with saline water. |
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Though shales are the most common of all sedimentary rocks they don't provide a very good indication of geologic conditions at the time of formation. Why? |
Shales appear in so many different geologic environments. |
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Define diagenesis. |
Diagenesis is a change undergone by sedimentary rock after its original deposition and during and after lithification. Alteration maybe chemical, physical, or biological, but not including metamorphism or weathering. |
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As a rule of thumb how does one anticipate the relative susceptibility to chemical weathering? |
Minerals of igneous rocks, when chemically weathered, display an inverse relationship to their order in Bowen's Reaction Series. First-formed minerals as the magma cools are the least stable at ordinary temperatures. |
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How are clastic rocks classified? |
Clastic rocks may be classified according to size of particles, sorting and distribution of particles, or chemical content of silica, feldspar, and calcite. |
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A well-sorted (or poorly graded) sediment or sedimentary rock contains how many grain sizes? |
Well-sorted (poorly-graded) sediments have only two or three grain sizes present. |
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What is a stratabound mineral deposit? |
A stratabound deposit is a mineral deposit that is confined to a single stratigraphic unit. |
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What is a stratiform deposit? |
A stratiform deposit is where the ore constitutes a layer or layers in the rock. It is also stratabound. |
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How do mineral resources differ from reserves? |
Reserves are deposits that are economically available and may be extracted profitably with existing technology. Resources are naturally occurring deposits in such amounts or concentrations to be minable now or in the future. Resources includes reserves, undiscovered reserves and any deposits from which economic value may be derived. |
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How are magmatic segregation deposits formed? |
Magmatic segregation deposits are produced by differentiation or direct crystallization of magma except for deposits that have a component of hydrothermal transport. They form in magma chambers and generally are deep-seated intrusive bodies. |
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What geologic conditions may form petroleum traps? |
Traps may be formed by: 1. deformation of reservoir rock, folding, faulting, or both, 2. stratigraphic variations in reservoir rock directly caused by the depositional environment (primarily) or unconformities (secondary), 3. hydrodynamic forces, 4. a combination of the above factors, 5. diapirs |
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What conditions do reservoir rocks need to have to allow migration, accumulation, and storage of petroleum to occur? |
Reservoir rocks need to be of sufficient porosity and permeability. Typical values of porosity range from 5% to 30%, most commonly in the 10% to 20% range. Permeabilities vary from 5-1000 millidarcys. |
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Archie's formula can be used to determine water saturation in an oil reservoir or the formation resistivity depending on the known variables. What is the formula? |
Sw n = a Rw = FR Rw φm Rt Rt
Sw = water saturation n = saturation exponent a = coefficient φ = porosity, expressed as a fraction m = cementation exponent Rw = resistivity of formation water, when 100% water saturated Rt = true formation resistivity Fr = formation resistivity factor |
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What is the formula used to determine the recoverable stock-tank oil (STO) and cubic feet? |
recoverable STO = A t φ So R FVF
A = area t = thickness φ = porosity So = oil saturation R = recovery factor FVF = formation volume factor
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Each of the intrusive igneous rocks has an extrusive rock which is its mineralogical equivalent. What are the rock types that are equivalent to granite, granodiorite, monzodiorite, and gabbro? |
Intrusive Extrusive Granite Rhyolite Granodiorite Dacite Monzodiorite Andesite Gabbro Basalt |
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List the 7 types of silicates and give a common example of each. |
Nesosilicates - single tetrahedra Olivine/garnet group Sorosilicates - double tetrahedra Epidote group Cyclosilicates - rings Beryl group/tourmaline Inosilicates - single chains Pyroxene group Inosilicates - double chains Amphibole group Phyllosilicates - sheets Biotite/muscovite/kaolinite/talc Tectosilicates - frameworks Feldspar/Zeolite group |
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Define Scour |
The powerful and concentrated digging action of flowing water during a flood, removing mud and silt. |
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What radiometric age-dating techniques would be used for materials that are greater than 10 million years old? |
Rubidium - Strontium ≥ 10 mil Uranium - Lead, Lead-Lead ≥ 10 mil Uranium - Helium 300,000 to 18 mil Fission track 100,000 to several bil Thermoluminescence Few hun to 1 bil Electro-spin resonance Few hun to 300 mil |
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Define Response Spectrum |
A description of a particular ground motion shown on a graph of spectral acceleration verses period (in seconds). |
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A plunging anticline will show closure in an outcrop pattern. In which direction does the anticline plunge with the respect to the closure? |
A plunging anticline is plunging in the direction of closure. |
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What can be inferred from a borehole log indicating a repetition of beds? |
A repetition of beds in cross-section indicates fault movement in which the hanging wall has moved up with respect to the foot wall (reverse faulting). |
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Are slickensides indicative of faulting? |
The presence of slickensides may indicate faulting but this feature also results from non-fault related movement in clays, such as shrinking and swelling. |
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What type of geologic feature might you expect from a mapped outcrop pattern that consists of a series of concentric circular shapes? |
1. Horizontal beds mapped on a rounded hilltop. 2. Horizontal beds mapped in an enclosed basin. 3. An intrusion with bands of contact metamorphism of varying degrees. |
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Chert is found commonly in the Coast Ranges Province of California. What is its depositional environment and how is it formed? |
Chert originates in shallow sea water. Some cherts result from the enrichment of silica in the sea water from volcanic rocks. They also may be formed by the accumulation of silicoious skeletons of silica secreting organisms. |
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According to the United Soil Classification System, gravels have a grain size greater than what diameter? |
Gravel - > No. 4 sieve or 4.76 mm |
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When observing cross-bedded sandstones, how do you know where the top of the beds are? |
The unit is right side up when cross-bedding is concave up. |
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What type of geologic units would constitute a "key bed"? |
Key beds are layers that have been deposited simultaneously over large areas. Good examples are volcanic ash, beds rich and fish scales, oysters or corals. |
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What type of fault might be represented by juxtaposition in map view of noncontiguous sedimentary formations? |
Sedimentary formations that do not occur next to each other may be moved laterally by strike slip faults. |
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Name and define the four various different types of unconformities? |
Angular unconformity - strata below the unconformity are cut off overlain at an angle by the beds above. Nonconformity - sedimentary deposits rest upon older igneous or metamorphic rocks. Disconformity - beds above and below unconformity are parallel, but unconformity not parallel to bedding. Paraconformity - unconformity is parallel to the strata above and below it. |
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How can the "Rule of V's" be used on a map with no topography? |
In using the Rule of V's to interpret direction of dip on a map with no typography you must first look at the V's downstream since V downstream is always dip downstream. When interpreting V's upstream you must observe the quality of the V. Shallow V's mean dip upstream and as the V's get deeper it passes from horizontal bedding to a dip downstream less than the valley gradient. |
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Define foot wall and hanging wall. |
Foot wall - block that underlies a non-vertical fault. Hanging wall - block that overlies a non-vertical fault. |
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What is a regressive sequence? |
Regression is the withdrawal of the sea from land. A regression is represented by limestone overlain by shale overlain by sandstone. |
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What is the order of deposition of evaporites? |
Order of Deposition calcium carbonate - calcite calcium sulfate - gypsum or anhydride sodium chloride - halite magnesium sulfate and chlorates sodium bromide and potassium chloride |
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What are the processes included in diagenesis? |
Diagenetic processes include: compaction, cementation, reworking, authigenesis, replacement by secondary minerals, crystallization of secondary minerals, leaching, hydration, bacterial action, or formation of concretions. |
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Give three examples of magmatic segregation deposits. |
1. Layered mafic intrusions (chromite) 2. Kimberlite pipes (diamonds) 3. Ophiolites (asbestos) |
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What is the importance of knowing water saturation in an oil reservoir? |
Below 60% of oil saturation, the reservoir will produce mostly water. |
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A poorly-sorted (or well-graded) sediment or sedimentary rock contains how many grain sizes? |
Poorly sorted (well-graded) sediment has a wide range of grain sizes present. |
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A plunging syncline may show closure in an outcrop pattern. In which direction does a syncline plunge with respect to the closure? |
A plunging syncline is plunging away from the closure. |
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According to the United Soil Classification System, a clay or silt would contain particles less than what diameter? |
Clay or silt - < No. 200 sieve or 0.074 mm |
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Contact metamorphism is associated with the intrusion of an igneous mass. What causes the metamorphic changes in this type of metamorphism? |
Metamorphic changes are caused principally by heat, but also by magma composition in deformation related to the intrusion. Pressures are relatively low (<3000 bars) while temperatures range from 200°C to 1000°C. |
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How is pyrite formed? |
Pyrite is formed by the indirect action of bacteria. The bacteria chemically change sulfur from an oxidized state (sulfate - SO4 -2) to a reduced state (sulfate - S-2). This change releases energy to the bacteria and hydrogen sulfide is produced. Hydrogen sulfide gas changes ferric ion (Fe+3) to ferrous ion (Fe+2) and precipitates pyrite. The bacteria can only grow in a reducing environment (or an environment without oxygen). |
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What regional metamorphic facies would be presented by low-grade metamorphic rocks such as slate, phyllite, fine-grained schist and quartzite, and serpentinite? |
Greenschist facies |
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Give two examples of depositional traps for petroleum? |
1. Lenses and facies of clastic and igneous rocks, such as lenticular sand bodies, barrier bars, channel deposits, and pinchouts. 2. Lenses in facies of biochemical rocks, such as biostromes, organic reefs, and bioherms. |
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Define Spiling |
Dowels or pins drilled or driven into the Earth around a shaft to provide support. |
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What is the "Invaded Zone" in a borehole? |
A transitional zone in a borehole located between the flushed zone and the uninvaded zone. It refers to the degree in which the mud filtrate penetrates the formation fluids, resulting in a transition from the mud filtrate saturation to the formation water saturation. |
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What are "API Units"? |
A unit of measurement of gamma rays. API stands for American Petroleum Institute. |
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What does a "Neutron Log" show and what is it commonly used for? |
A radioactivity log curve of the intensity of radiation produced when the rocks in a borehole are bombarded by neutrons. It indicates the presence (but not type) of fluid. It is often used in association with the gamma ray log to distinguish porous and nonporous formations. |
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What is "Borehole Geophysics"? |
The science of recording and analyzing measurements of physical properties made in wells or test holes. |
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What does a "Normal Resistivity Log" measure and how is it set up? |
A log that makes measurements of the resistivity of formations using 4 electrodes set up in a standard 16- or 64-inch spacing. |
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What is shown by a "Caliper Log"? |
A well log that shows the variations with depth in the diameter of an uncased borehole. |
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The measurement of what is shown on a "Resistivity Log"? |
A log that makes quantitative measurements of the specific resistance of a material to the flow of an electric current. |
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What does a "Gamma Ray Log" measure and what is it commonly used for? |
The radioactivity log curve of the intensity of natural gamma radiation emitted from the rocks in a borehole. It is commonly used to differentiate between shale (with a high gamma reading) and other sedimentary rocks. |
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What does a "Spontaneous Potential Log" show and what is it a result of? |
A log of the difference in DC voltage between an electrode in a well and an electrode at the surface. The difference in voltage is mostly a result of the electrochemical potentials that develop between dissimilar borehole and formation fluids. |
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What does the "Single-Point Resistivity Log" show and what area is it limited to? |
A log that measures the resistivity using two electrodes and having a limited area of investigation of from 5 to 10 times the electrode diameter. |
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What is the "Area of Influence" of a well? |
The area within which the potentiometric surface is lowered by withdrawal or raised by injection, of water through a well. |
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What does a "Well Log" show? |
A graphic record of the measured physical characteristics of a soil or rock section encountered in a well plotted as a function of depth. |
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Define Aquifer |
A geologic unit that is saturated and sufficiently permeable to transmit significant equal economic quantities of water to wells and springs. |
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What is "Connate Water"? |
Water trapped in the pores of a sedimentary rock at the time of deposition; fossil water. |
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Where is the "Capillary Fringe" located and how is it defined? |
The lowest part of the zone of aeration, immediately above the water table, where water is under pressure that is less than atmospheric pressure. |
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What is a "Darcy" and what is its value? |
A unit of interested permeability = 9.87 x 10-9 cm2. |
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What is a "Cone of Depression" and what does it define? |
A depression in the potentiometric surface of groundwater that has the shape of an inverted cone and develops around a well from which water is being withdrawn. It defines the area of influence. |
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What is "Darcy's Law"? |
The basic equation describing groundwater flow put forth by Darcy: Q = KiA.
In another form: vd = - K h1 - h2 = Q l A |
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What is the definition of "Confined Aquifer"? |
An aquifer overlain by a confining layer of low permeability. |
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What is a "Discharge Area"? |
An area where subsurface water is discharged to land, bodies of water, or the atmosphere. |
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What is "Effective Porosity (ne)" and what term is often used analogously? |
The percentage of the total volume of a soil or rock that consists of interconnected pore space. The term is sometimes used analogously to specific yield. |
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Define Drawdown |
The amount of water level in a well is lower due to withdrawal of water. |
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What is "Field Capacity" and what is it dependent on? |
The quantity of water held by soil a rock against the pull of gravity. Field capacity is dependent on the length of time the soil or rock has been undergoing gravity drainage, while specific retention is not. |
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What is "Hydraulic Gradient (i)"? |
The change in head per distance along a flow path between two points where head is measured. Gradient is a dimensionless quantity.
i = hA - hB = dh l l |
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What is in "Intrinsic Permeability (ki)" and what is it dependent on? |
A property of the porous medium that measures the relative ease with which a fluid can be transmitted through it under a hydraulic gradient. It is dependent upon the pore size and is measured in darcys. |
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What is a "Flow Net"? |
Two-dimensional representation of flow lines in equipotentials. |
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What is the source of "Juvenile Water"? |
Water that is derived directly from magma and is thought to have come to the Earth's surface for the first time. |
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What is "Have"? |
A measure of the potential energy of a fluid at any given point with respect to a given datum. In practice, it is the elevation to which water rises at a given point as a result of reservoir pressure. |
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What is a "Meinzer"? |
A unit of hydraulic conductivity in gpd/ft2. Rate of flow in gallons per day through a cross section of 1 square foot under a unit hydraulic gradient at 60°F. |
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Define "Hydraulic Conductivity (K)" |
The capacity of a porous medium to transmit water. The rate at which fluid can move through a permeable medium depends on properties of the fluid (viscosity and specific weight) and properties of the medium (intrinsic permeability). |
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Define "Perched Ground Water" |
Unconfined groundwater separated from an underlying body of groundwater by an unsaturated zone. |
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How is a "Packer Test" run and what is it used for? |
An aquifer test in which two inflatable seals (or packers) are set in an open borehole to prevent movement of ground water in the test section while the permeability of the isolated rock is determined. |
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What is "Permeability"? |
The property of a porous rock or soil for transmitting of fluid. It measures the relative ease of flow under unequal pressure. |
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Define Recharge Area |
An area where water infiltrates downward into the saturated zone. |
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What is "Porosity (n)"? |
The percentage of the bulk volume of a rock or soil that is occupied by void space. |
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Define Runoff (R) |
The part of precipitation appearing and surface streams. |
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What does the "Potentiometric Surface" represent? |
A surface that represents the total head of ground water and is defined by the level to which water will rise in a well. |
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How is a "Slug Test" done? |
An aquifer test made either by pouring a small charge of water into a well or by removing a slug of water from the well. The removal of water from the well is also called a bail-down test. |
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What is a "Pumping Test" and what do you observe? |
A test made by pumping a well for a period of time in observing the change in hydraulic head in the aquifer. |
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What is a "Specific Retention (Sr)"? |
Ratio of the volume of water a soil or rock can retain against gravity drainage to the total volume of the soil or rock, usually stated as a percentage. |
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Define "Specific Storage (Ss)"? |
Amount of water per unit volume of a saturated formation that is stored or expelled from storage due to compressibility of mineral skeleton and pore water per unit change in head. Units are ft-1. |
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What is "Specific Yield"? |
Ratio of the volume of water that drains from a saturated soil or rock due to gravity to the total volume of soil or rock, stated as a percentage. |
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What is the definition of "Storativity or Storage Coefficient (S)" and in a unconfined aquifer what term is used interchangeably? |
Volume of water that a permeable unit releases from or takes into storage per unit surface area of the aquifer per unit change in head. In a unconfined aquifer, storage ≈ specific yield. |
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What is "Transmissivity"? |
The capacity of an aquifer to transmit water of the prevailing kinematic viscosity. T=Kb, where b=saturated thickness of the aquifer. Dimensions are gpd/ft or ft2/day. |
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What type of aquifer has a water table? |
Unconfined Aquifer |
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What is "Underflow (U)" and in what region is it most often used? |
Ground water that flows beneath the bed or alluvial plain of a surface stream, especially in arid regions. |
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What is the "Vadose Zone or Zone of Aeration" and how does unsaturated zone compare? |
A subsurface zone containing water under pressure that is less than atmospheric pressure. A synonym of vadose zone is unsaturated zone; however, the "unsaturated zone" contains the capillary fringe which is saturated. |
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Define "Water Table" |
The surface within unconfined groundwater at which the hydraulic pressure is equal to the atmospheric pressure. |
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What is a "Watershed"? |
The region drained by a stream or body of water, or a drainage divide. |
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How is "Well Efficiency" presented? |
As a ratio in percent of theoretical drawdown to actual drawdown measured in a well. |
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Of the CERCLA and RCRA, which Act covers existing hazardous waste sites? |
Resources Conservation and Recovery Act (RCRA), 1976, as amended. U.S. law that regulates existing hazardous waste facilities; ground water requirements in the corresponding regulations are performance standards. |
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What is the TEGD and what is the purpose of the document? |
TEGD - Technical Enforcement Guidance document. Technical guidance document for meeting the ground water monitoring performance standards in the RCRA regulations. |
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According to the TEGD what does a minimum investigation include? |
A minimum investigation for site characterization includes: geologic data review and mapping, soil borings, material testing and analysis, piezometer studies, slug tests and/or pumping tests. Geophysical surveys or also useful. |
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The TEGD requires a minimum of how many detection monitoring wells and where should they be placed? |
Placement of Detection Monitoring Wells - one up gradient well, 3 down gradient wells at a minimum. Downgradient wells should be placed to intercept containment flow paths. Well clusters, screened at different stratigraphic horizons, may be necessary to sample all significant flow zones. |
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What factor should be taken into consideration when spacing wells and determining sample intervals? |
Horizontal spacing between wells depends on site-specific factors such as hydrogeology, dispersivity, seepage velocity, facility design and waste characteristics. Vertical sampling intervals are determined by stratigraphic horizon through which flow will occur, physical/chemical characteristics of hazardous waste, and chemical processes of dispersion and sorption. |
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What is the goal of site characterization? |
The goal of site characterization is to identify potential pathways for containment migration in the uppermost aquifer. The "Uppermost Aquifer" is considered to include all of the hydraulically interconnected units that could be pathways for containment migration. |
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According to the TEGD, what is the preferred method of drilling monitoring wells? |
Use the least contaminating, least damaging drilling methods first, i.e. auger (hollow-stem, continuous, solid-stem continuous) - cable tool - air rotary. Mud rotary id the choice of last resort used only when all other methods fail. Bentonite, barium sulfate, biodegradable, or organic polymer muds degrade water quality and should not be used. |
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According to the TEGD, what techniques should be used for logging monitoring wells? |
Techniques might include logging of drill cuttings, collection of representative samples by split spoon, Modified California sampler, Shelby tube or Pitcher tube, and borehole geophysical methods utilizing spontaneous potential (SP), resistivity (single-point resistance, normal and lateral), natural gamma ray, or neutron. |
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In order to ensure a lifetime of 30 years or more a monitoring well should be constructed with what materials? |
Use inert (Teflon or stainless steel) casing and well screen in the saturated Zone. PVC or other non-inert material may be used above the saturated zone. Use chemically inert, well-rounded, and dimensionally stable filter pack (clean quartz sand, silica, glass beads) placed 2 ft or less above the screen and constructed on site. |
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According to the TEGD, what is the appropriate annular sealant in a monitoring well? |
An appropriate annular sealant is: a minimum of 2 ft of sodium bentonite pellets placed above the filter pack when in the saturated zone, cement/bentonite mixture in unsaturated zone below frost zone, and continuous pour concrete cap and well apron from below the frost zone to the surface. |
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What type of test is used to determine potential yield or specific capacity? |
The bail down test is used to determine potential yield or specific capacity. |
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Flow of ground water is controlled by which of the following: porosity, hydraulic conductivity, hydraulic gradient or intrinsic permeability? |
Hydraulic conductivity, hydraulic gradient and intrinsic permeability. |
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What would be the range of values for storage coefficient or storativity (S) for a confined aquifer? For an unconfined aquifer? |
S = Confined aquifer = 0.001 to 0.00001 (10-3 to 10-5) S = Unconfined aquifer = 0.01 to 0.3 |
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What is a constant-rate pumping test used for? |
The constant-rate pumping test is used to obtain the values of transmissivity and storage for the aquifer and the specific capacity of the well. |
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Where would you expect to find turbulent groundwater flow? |
Turbulent ground water flow may be found in surface waters or in some wells when they are pumping at a high rate. |
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Under what circumstances would you use to Dupuit equation to determine ground water flow? What are the assumptions used in the Dupuit equation? |
The Dupuit equation is used for steady flow in a unconfined aquifer lying above an impervious boundary. Assumptions used in the Dupuit equation are that the hydraulic gradient equals the slope of the water table, the direction of the ground water flow is horizontal and contours of equal head are vertical. |
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Where salt water is formed adjacent to fresh water in coastal areas what is the principle that describes the relationship of the salt-water - fresh-water interface? |
The Ghyben-Herzberg principle says the depth to which the freshwater extends below sea level is approximately 40 times the height of the water table above sea level.
Z = 40 ht Z = depth of fresh-water - salt-water interface below sea level ht = height of the potentiometric surface above sea level. |
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What methods can be used to control and prevent sea water intrusion into a fresh water aquifer? |
1. Control pumping to maintain seaward hydraulic gradient in the fresh-water aquifer 2. Artificial recharge at ground water to maintain seaward gradient 3. Place pumping wells between ocean and water-supply wells 4. Create an injection barrier ridge (a fresh-water ridge produced by recharge wells) between ocean and water-supply wells 5. Construct a man-made subsurface barrier (such as a slurry wall) |
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In a hydraulic budget problem, what equation would you use to determine the change of total storage? |
dSr = P - E + R + U
dSr = change in total storage P = precipitation E = evapotranspiration R = runoff = stream~inflow - stream outflow U = underflow = ground-water inflow - ground-water outflow |
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What is Stiff or butterfly diagram and what is it used for? |
The Stiff diagram is a graphical representation of chemical analyses plotting the cations versus the anions projecting outward from a zero reference line in the center of the diagram. It produces a visible diagram that looks somewhat like a butterfly. They are used when making visual comparisons between waters from different sources. |
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What is retardation with respect to contamination of ground water? |
Retardation is the process by which solutes are removed from the ground water. |
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When diagramming a flow net showing equipotential lines and flow lines what relationship must the lines have to one another? |
The equipotential lines must be perpendicular to the flow lines and closely approximate square shapes. |
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What is the US EPA recommended maximum TDS to ensure acceptable aesthetic and taste characteristics for drinking water? |
For drinking water, the maximum TDS = 500 mg/l |
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At what value of TDS is water considered to be saline? |
TDS ≥ 10,000 mg/l for saline water |
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In a time-drawndown pumping test the line drawn on the semilog paper through the drawdown measurements is drawn through those points that are further away from the time the test started. Why? |
The points after the first 10 minutes are the most accurate because there has been time to stabilize or for the cone of depression to reach a steady-state condition. In fact the data taken in the first 10 minutes is not included in the analysis. |
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In a distance-drawdown pumping test the line drawn on the semilog paper through the drawdown measurements is drawn through those points that are closest to the pumping well. Why? |
In a distance-drawdown test the points closest to the pumping well are the most accurate representation of the conditions because of the further away from the pumping well the greater the likelihood that factors are present that would affect the water levels. |
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Define Excavation |
Any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal. |
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What is lagging? |
Boards which are jointed, side-by-side, lining an excavation. |
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Define Maximum Capable Earthquake |
The maximum level of ground shaking ever expected at a site within the known geological framework. In Seismic Zones 3 and 4, it is the earthquake ground motion that has a 10% probability of being exceeded in a 100 years. |
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What is the "Seismic Zone Factor"? |
A numerical factor assigned to each seismic zone. The factor is used to calculate forces in the building design process. |
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What is a "Time History"? |
A record of ground acceleration versus time during an earthquake. |
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Define "Body-Wave Magnitude (Mb)" |
The magnitude of an earthquake as estimated from the amplitude of the body waves. |
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What is a percolation test used for? |
A percolation test is an in-situ test that determines the suitability of a soil for a sewage disposal system (leachfield) |
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What is rippability and what geophysical method is used to help determine that characteristic in subsurface materials? |
Rippability is the ease with which soil or rock can be excavated mechanically. Seismic refraction is used to determine the seismic velocity of the earth materials. Other parameters such as uniaxial tensile strength, weathering, abrasiveness, and spacing of discontinuities are also considered to obtain a more representative assessment of rippability. |
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Seismic refraction is based on what? Why is it used? |
Seismic refraction methods are based on the travel times of the seismic waves that pass through materials of differing densities, in order to map the layers. |
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What is a Standard Penetration Test (SPT)? |
A standardized soil sampling procedure in which a 140-lb hammer is dropped 30 inches, driving a two-inch diameter split-spoon sampler 18 inches. The blow count to drive the sampler through the last 12 inches is correlated with the soil conditions. |
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What is compaction? |
Compaction is the process of increasing the density of a soil (usually of fill) by rolling, tamping, vibrating or other mechanical means. |
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How does consolidation affect the soil? |
Consolidation is the gradual or slow reduction in volume and increase in density of a soil mass in response to increased load or compressive stress. |
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What is a "Quick Condition"? |
A quick condition is the condition of soil in which a decrease in intergranular pressure allows water to flow upward with sufficient velocity to reduce significantly the soil's bearing capacity. |
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The term karst is used to describe what feature? |
Karst is a term that is applied to the topography of a region which is underlain by limestone, dolomite, gypsum, or other rocks that are easily soluble. |
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What features are characteristic of karst terrain? |
Karst topography is characterized by surface depressions into which water is intercepted and diverted into underground caverns and passageways. |
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What are the 4 conditions necessary for the development of karst terrain? |
1. A soluble rock, usually limestone, at or near the surface 2. A dense rock, highly jointed and pervious 3. Entrenched valleys below uplands underlain by soluble and well-jointed rocks 4. Region of moderate to abundant rainfall |
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What regions of the US are most affected by karst features? |
Karst features are found in all states. The four most important regions in the U.S. are: 1. Central Florida, 2. Salem-Springfield plateau area in SW Missouri, 3. A NW-SE trending belt from south-central Indiana into west-central Kentucky, 4. Great Valley region of Tennessee, Virginia, Maryland, and Pennsylvania. |
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What is the red clayey soil found mantling the ground surface and extending into joints or fractures resulting from surface or near surface solution, usually found on moderate to gentle slopes? |
Terra rossa |
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What are the grooved or rilled surfaces characteristic of lapies a result of? |
The solution of limestone by flowing rainwater on inclined surfaces. The grooves range and width from a few millimeters to more than a meter in width and commonly result in knifelike ridges. |
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What is the most commonly observed feature of karst terrain? |
Sinkholes |
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What is the origin of sinkholes? |
Sinkholes have two origins; either the solution of the rock beneath the soil (a doline) or the collapse of the rock over an underground cavity (a collapse sink). In an area riddled with sinkholes, as the sinkholes enlarge with time they may expand and combine with adjoining sinkholes to form a compound sinkhole. |
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A pond or lake resulting from the clogging of clay of a doline sinkhole at perches above the water table is called a ?. |
Sinkhole pond or karst lake |
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A hole in the bottom of a sinkhole which allows surface water runoff or streams to flow into the subsurface cavities is called ?. |
Swallow hole |
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A ? is a hole in the ground through which one can observe an underground stream flowing from one cavern to another or a hole in a cavern which breaks the surface. |
Karst window |
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What is a uvala? |
An elongated karst depression that gas formed by collapse or solution. These features can extend from 1,000 feet to a mile or more. |
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What is a polje? |
A sinkhole formed by solutional modification of the rock in a previously faulted or folded structure. This feature is the largest karst form and can be up to 30 miles or more in length and breadth. |
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What causes solution sinks? |
Solution along joints are faults creates concurrent subsidence and a surface depression. |
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A limestone plain exhibiting sieve-like characteristics resulting from numerous sinkholes intercepting any surface waters and diverting them to a subsurface channel is called ?. |
Karst plain |
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What are sinking creeks? |
Surface creeks or streams which disappear underground or into a swallow hole in karst terrain. |
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What is a blind valley? |
A valley that has no surface exit for its drainage. The valley ends abruptly when the surface water disappears underground at a swallow hole. When the stream becomes a sinking stream. |
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Name 2 natural processes that produce natural tunnels and bridges. |
These features can be produced by the underground flow of water in karst terrain or when the flow of molten lava produces a cooled surficial crust which has cooled and the lava subsequently flows out of the tunnel formed. When the tunnel sections collapse leaving only small sections, bridges are formed. |
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How do caverns form? |
Caverns are created by solution of limestone along joints and bedding planes. |
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What is a travertine and where is it found? |
Travertine is a deposit of calcium carbonate precipitate that can be found in limestone caverns coating the cavern walls, floors and ceilings or deposited by springs. |
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The travertine deposits that result from the calcium carbonate-rich water dripping from the ceiling of a cave or cavern are called ?. |
Dripstone Stalactites are the downward protrusion of these deposits and stalagmites are the upward protrusion. |
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Where does helictite form and under what conditions? |
Helictite, an irregular twig-like deposit, forms in a cavern where there is not enough water to form drips but the surface remains damp or the water comes from a tiny hole or tube within the deposit in the water flows out the end. |
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What are glacial features associated with alpine glaciation found in the U.S.? |
Alpine glacial features are found in the mountainous areas, particularly in the Rockies, the Cordilleran ranges, and the Sierra Nevadas. |
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Where are the glacial features associated with the continental glaciation found in the U.S.? |
Features associated with continental glaciation can be found in much of the central and northern U.S. |
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What 5 conditions must be met to classify a snow or ice field as a glacier? |
1. There must be a large accumulation or mass of ice and snow. 2. It must be located on or principally on land. 3. It must be formed by compaction and recrystallization of snow. 4. There must be evidence of past or present movement. 5. The glacier remains from year to year. |
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What is a cirque erosional or depositional? |
A cirque is a horseshoe-shaped hollow high on a mountainside that was created by the erosive action at the head of a glacier. |
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What is a small deep lake formed in a cirque basin called? |
Tarn |
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What causes glacial polish? |
Glacial polish is a smooth surface produced on bedrock by abrasion resulting from the movement of a glacier. |
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What are the lines scraped into the bedrock by rocks being carried along at the base of the glacier called? |
Striations The striations generally indicate the direction of glacier. |
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What is the steep-sided valley which may extend down from a cirque and which glacial action has widened and deepened an existing valley called? |
Glacial trough (U-shaped valley) |
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Glacial steps or stairways consists of a series of cross-valley steps extending down from the cirque which are characterized by a relatively flat floor or with a slight upvalley slope broken by steeper sections stepping down valley. What are the lakes called that occupy these steps? |
Paternoster lakes |
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What causes a hanging valley? |
Hanging valleys are U-shaped glacial tributary valleys truncated by a deeper U-shaped glacial main valley leaving a valley whose mouth is relatively high on the main valley wall. The discordance is due to the greater erosive power of the main glacier. |
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What is the jagged sharp sawtooth-like ridge that results from the growth of cirques on opposite sides of a mountain ridge by alpine glaciation called? |
Arête |
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A col or a horn are features associated with or arêtes. What is their relationship to the all arête? |
A col is a narrow sharp-edged pass or sag between cirque head and side walls along an arête and the horn is a jagged sharp peak at the high point in an arête which has been sculpted by the erosional action of three or more cirques. This pyramidal feature is the remainder of the original mountain summit in a region modified by alpine glaciation. |
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What geologic processes cause truncated or faceted spurs? |
Truncated ridges, which characteristically have an inverted V-shaped face, can result from either the abrasion of glacial action as it straightens the valley or by faulting. |
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What do the presence of drumlins indicate? |
Previously deposited glacial materials that have been overrun by another advance of the glacier. |
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Glacial deposits consisting of a heterogeneous mixture of clay, silt, sand, gravel, and boulders in an unsorted, unstratified, usually unconsolidated deposit which was deposited directly by a glacier without having been reworked by meltwater are called ?. |
Till |
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Are glacier deposits formed from direct deposition of materials by glacial-fluvial or glacial-lacustrine processes stratified or unstratified? |
Stratified deposits |
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Are glacier deposits formed from direct deposition of materials by glacial-fluvial or glacial-lacustrine processes stratified or unstratified? |
Stratified deposits |
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What is a moraine? |
A moraine is a mound or ridge composed of accumulated glacial drift or till deposited directly by the glacier. |
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What are moraines composed of? |
Moraines are composed of a heterogeneous collection of unsorted and unstratified clay, silt, sand, gravel and boulders. |
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What features are characteristic of larger clasts within a moraine deposit? |
Many of the larger clasts are faceted and have striations or polish due to the abrasion during the movement of the glacier. |
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What is a terminal moraine? |
An end (terminal) moraine is in a arcuate ridge-like feature that has been deposited at the terminus of the glacier, marking the furthest progression of the glaciation. |
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Why are older moraines often missing? |
Older terminal moraines that are not the maximum extent of glaciation are typically destroyed by the subsequent glacial advances incorporating the older moraine material with the younger. |
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What do recessional moraine (or retreat moraines) result from? |
A temporary hiatus in the overall retreat of the glacier. The youngest age moraine is located upstream. |
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A linear moraine located along the edge of a valley glacier and composed of materials deposited on the glacier from the valley walls is called a ?. |
Lateral moraine |
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What causes a medial moraine? |
When the lateral moraines from two valley glaciers merge to join the two inside lateral moraines. |
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What is a valley train? |
A valley train is a long, narrow deposit of outwash (sand and gravel), deposited by glacial meltwater, which begins at the end moraine and extends downvalley on the outwash plain. |
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The annual rhythms of the accumulation of sediment layers in an lacustrine environment are called ?. |
Varves |
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A hummocky landscape consisting of knolls or mounds of glacial drift in an area also interspersed with basins (often containing water) is called ?. |
Knob and basin topography or knob and kettle topography |
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What is a Roche moutonnèe? |
An elongated bedrock knob which is oriented parallel to the direction of glacial flow and has a smooth rounded upstream end and usually a steep rough downstream end where the glacier plucked out the rock as it moved away.. |
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What is a till plain? |
A relatively flat to undulating surface resulting from deposition by an ice cap of glacial till which covers an extensive area and buries the preglacial typography. |
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What is drift? |
A general term that includes these deposits can be further described by the terms till, stratified till, and deposits of glacio-fluvial, glacio-lacustrine, glacio-eolian, and glacio-marine origin. All rock and associated material that has been carried by and deposited by a glacier, glacier ice, or running water from a glacier. |
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What is the difference between end moraines (or terminal moraines) found in areas of continental glaciation as compared to those found in areas of alpine glaciation? |
The end moraines found at the maximum extent of a continental glaciation are similar to those found in alpine glaciation though tend to be much more extensive and often have less steep slopes, occasionally making it difficult to distinguish between the ground moraine and the end moraine materials. |
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What is a drumlin? |
An elongated ellipsodial feature composed of a variety of till materials ranging from clays to relatively large rock fragments, some have a bedrock core but may also include fluvial deposits from meltwater. These streamlined hills are often clustered in are found near the terminal or recessional moraines. Thought to be formed by the flow of ice around an obstacle, depositing the soil and rock materials when the stress is released after having passed the obstruction. |
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How would you describe the materials found in an outwash plain? |
Outwash is stratified debris that was carried by meltwater streams both in front of and behind the terminal or end moraine. The outwash plain is typically comprised of coarser grained materials closer to the terminus of the glacier grading to finer materials with increased distance. |
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How is an esker formed? |
An esker is a serpentine shape deposit of sorted sand and gravel that developed as the load carried by the streams flowing beneath, within, and above the glacier, once it has become stagnant, is dropped. The appear as inverted stream channels that lie higher than the surrounding area. |
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What is a kettle? |
A kettle is a depression in the postglacial terrain formed by the melting of a large stagnant ice block allowing the settlement of the overlying glacial drift. In some areas outwash plains are pitted with many kettles. This could result from the stagnation of a laterally extensive sheet of ice with varying thickness. |
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What are kames? |
Kames are small steep-sided hummocks of unconsolidated, stratified, ice-contact drift composed of sand and gravel that has been deposited in crevasses at the surface of the glacier, on an irregular surface of stagnant glaciers, or from streams flowing at the edge of the glacier along the contact of the ice with the valley wall. |
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Why are most wind erosion features relatively small? |
Since sand grains can only be lifted a small amount above the ground these features usually are small in scale but unique in appearance. |
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What are ventifacts? |
Ventifacts are stones that have been abraded by the wind on at least one side so they are polished or faceted. They are usually only found in a unique environment of no vegetation, strong wind and plentiful sand. |
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A combination of wind and water erosion (deflation) in an area where there are resistant rocks capping weaker more easily eroded rocks create ?. |
Pedestal rocks - commonly called balanced rocks. |
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What is a blowout? |
A blowout is a depression caused by deflation in an area where either migrating dunes exist or a small break develops in the surficial integrity of a stabilized windblown deposit. |
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What is the relatively flat residual surface of closely-packed, wind-polished stones resulting from the removal of the fine-grained particles by wind and sheetwash called (often these remaining stones are somewhat cemented in place)? |
Desert pavement - sometimes called desert armor. |
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What happens when a stabilized dune field is disturbed? |
When dune fields that have been stabilized by climate change or growth of vegetation are disturbed they often become problematic, resulting in the reactivation of dune migration or the development of blowouts. |
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What is the process that results in well-sorted grain sizes in sand dunes? |
Typically, in eolian deposits the wind will winnow out the fines (silt-sized material) causing the sand-sized particles and silt-sized particles to accumulate differentially and therefore they are not commonly found together. |
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Small-scale features that are usually found on the surfaces of sand deposits resulting from the flow of wind or water over the surface are called ?. |
Ripple marks |
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What can be determined by the shape of the ripple mark? |
The shape of the ripple mark can be an indicator of the direction of flow of the wind or water or of the depositional environment. |
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What type of soil materials are found in dunes? |
Most dunes are composed of a well-sorted (poorly graded) sand. |
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What are the two types of crescent-shaped sand dunes and how are they distinguished? |
Barchan dunes have tails to leeward, rarely vegetated. Parabolic dunes have tails to windward, often associated with some vegetative cover. |
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What type of sand dune forms perpendicular to the wind, exhibits the traditional gentle windward slope with the steep slip face nearing the angle of repose? Both the Barchan and Parabolic dunes are a variety of this type of dune. |
Transverse dunes |
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What type of dune forms parallel to the wind? |
A longitudinal or seif dune is oriented parallel to the wind, thought to develop in areas in which the prevailing wind causes the dune to lengthen in the direction of the wind but the dune height increases due to the cross winds during periods of irregular wind flow. |
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What is saltation? |
The bouncing of sand particles along the ground surface where the impact of the grains triggers the bouncing of the grains which have been impacted. |
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What is a sand sheet? |
Sand sheets (often called sand drift) are extensive flat areas covered with a coarse-grained sand that does not form dunes, but typically are covered with ripple marks. |
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What is loess? |
Loess is a wind-blown silt that is calcareous, homogeneous, permeable. Loess covers extensive areas in the Pacific Northwest in Mississippi Valley regions. |
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Define deflation |
The removal of loose material by wind erosion. |
