What is meant by “ionic substitution” of elements in minerals, and how does this lead to variability in the compositions of some groups of minerals? | Online Homework Help

Final Study Guide
The final exam will be comprehensive but will focus more on material covered since the last in-class exam. There will be a total of ~80 multiple choice questions, 40 from the first 2/3 of the course and 40 from the material we have covered since the last exam. It may include a few questions based only on the reading but will focus mostly on material covered in class. You may bring two 3×5 reference cards to the exam with you loaded with whatever information you think may be useful. In aIDition, as I explained in class, I will post a “word cloud” with most of the words appearing on the exam, and you may have an aIDitional, 3rd card with definitions of any words that you are not familiar with. Good luck!
Outline of Topics covered by exam:
Part I
I. Minerals – Ch. 3
* Understand the different chemical bonds and their significance for the physical properties of minerals. For example, contrast diamond and graphite with respect to their crystal structure, the nature of the chemical bonds in each, and the following physical properties: hardness, cleavage, density, streak (i.e.,color of the powdered mineral), and luster. What gives diamond and graphite such different properties considering that they both consist of pure carbon?
* What is meant by “ionic substitution” of elements in minerals, and how does this lead to variability in the compositions of some groups of minerals?
* Cross out the three elements that do not belong in this list:
O, Si, Al, C, Mg, Fe, N, Ca, Na, K, H
What is the significance of the elements remaining on the list?
* What is the basic building block of the most abundant general family of minerals (the silicates)?
* Contrast the way quartz and olivine maintain charge balance in crystal structures based on complex ions of SiO4-4 (silica tetrahedra).
* Know which mineral is most abundant in the Earth’s mantle (olivine) and which minerals are most abundant in the Earth’s crust (i.e., quartz and the feldspar group).
* Name a mineral group that uses 6 of the 8 most abundant elements (hint: it is the most abundant group of minerals in the Earth’s crust — see above).
* What is the difference between chrysotile asbestos and the various types of amphibole asbestos. Why is the latter so much more hazardous?
* The most important group of minerals for engineers to understand are the clay minerals. What are the chief properties of the clay minerals? Strength? Compressibility? Permeability? Expansivity?
Understand their colloidal properties and how their colloidal behavior influences important engineering properties such as cohesion, impermeability, and plasticity.
Contrast the T-O structure of kaolinite with the T-O-T structure of montmorillonite and understand how these contrasting crystal structures influence the cation exchange capacities and especially the capacity to absorb and expand in interaction with water.
II. Igneous Rocks, Volcanism and Related Processes – Ch. 4
* What is the basis for the subdivision of the igneous rocks into volcanic (extrusive) and plutonic (intrusive). How are volcanic and plutonic rocks distinguished? (grain size)
* What is the basis for the subdivision of igneous rocks by compositional category (i.e., felsic, intermediate, mafic, and ultra mafic.
* Key igneous rock types to know: plutonic – peridotite, gabbro, diorite, granite; volcanic – basalt, andesite, rhyolite.
* What kind of igneous rocks are most abundant in the mantle? The oceanic crust? The continental crust?
* Be prepared to relate the major compositional categories of igneous rocks to plate tectonics and to the important process of partial melting. E.G., If oceanic crust is formed at mid-ocean ridges by partial melting of underlying mantle rock, then why is oceanic crust mafic rather than ultramafic in composition? (I.E., Relate to the fact that the melt is enriched in silica during partial melting).
* Be prepared to relate the formation of different types of igneous rocks to the plate tectonic environments in which they occur. ; subduction zones and arc volcanism – intermediate composition; continental settings such as rifts or continental hotspots – felsic).
Mid-ocean ridges (e.g., Iceland) and oceanic hotspots (e.g., Hawaii) – mafic magmatism
How are magmatic arcs related to the subduction process, and why can they be considered the birthplace of new continental crust? Relate to the intermediate composition of the magmas.
Continental Rifts and continental hotspots – felsic magmatism (why?)
* Characterize the general strength and permeability properties or igneous rocks. How are these properties affected by such features as joints and vesicular (i.e.,gas bubble) texture in volcanic rocks.
* What ultimately drives volcanic eruptions, and how does the gas content and viscosity of the lava affect the explosiveness of eruptions? How is gas content and viscosity related to silica content? Accordingly, what compositional categories of volcanism tend to produce the most explosive eruptions?
* In mafic (basaltic) eruptions, contrast aa and pahoehoe lava. In intermediate to felsic eruptions be prepared to identify ash flow, ash fall, and lahar.
* How does the composition and style of eruption influence the landforms developed, e.g., shield volcanoes vs. stratovolcanos vs. calderas.
* How can engineers and scientists help society to prepare for and contend with the diverse risks associated with volcanism?
III. Sedimentary Rocks – Ch. 5
* Compare & contrast the two basic categories of sedimentary rocks. What is the origin of each type?
* On what basis are the detrital sedimentary rocks further subdivided? (Grain size)
* What other textural characteristics are important in controlling the behavior (including the engineering properties) of sedimentary rocks? (e.g., sorting, roundness & sphericity)
* On what basis are the chemical sedimentary rocks subdivided? (Mineralogical composition)
* Key sedimentary rocks to be familiar with: detrital – shale, siltstone, sandstone, conglomerate; chemical – limestone & dolostone, rock salt, gypsum, coal.
* Be able to match the different kinds of detrital sedimentary rocks with their characteristic grain size range and be able to match the chemical or biogenic sedimentary rocks with the minerals that compose them.
* How are sedimentary rocks important to the economy, esp. to Ohio’s economy?
* Geologists are interested in sedimentary structures because they give important clues to the history of events at the Earth’s surface at the time of deposition. What are dunes, ripple marks and cross beIDing and how do geologists interpret the formation of these features?
* What sedimentary structures can provide important “way-up” indicators, and why is this important to geologists (refer back to geologic history).
* Detail the most important engineering concerns in dealing with sedimentary rocks. Why are sedimentary rocks of so much concern to engineers?
IV. Metamorphic Rocks – Ch. 6
* What are the basic controls on the process of metamorphism?
* What is the geothermal gradient? What is metamorphic grade?
* Contrast lithostatic (hydrostatic) pressure with differential stress. How does the presence of a differential stress affect the development of metamorphic rocks?
* Relate the various environments of metamorphism and the types of conditions found in each environment to the fundamental concepts of plate tectonics.
* What is metamorphic foliation, and how does it form? What concern is it to engineers?
* Key metamorphic rock types to know: quartzite, marble, slate, phyllite, schist, gneiss.
* Why are metamorphic rocks important despite being less common at the Earth’s surface? What are the principal concerns of engineers in dealing with metamorphic rocks?
* Of the three major rock families, which tend to be strongest or weakest? Which tend to be most or least permeable? Be ready to analyze and discuss the chief factors controlling rock strength.
V. Plate Tectonics – Plate tectonics is covered on p.41-51 of Ch. 2 in your text.
* Be familiar with the general compositional and rheological structure of the Earth — e.g., core-mantle-crust; lithosphere vs. asthenosphere.
* Contrast continental & oceanic crust.
* What are the basic ideas of plate tectonics?
* What are the basic types of plate boundaries? E.G., divergent (Mid-oceanic ridges and continental rifts), convergent (subduction zones vs. continental collision zones), and transform (oceanic or continental). You should be able to identify classic examples of each, such as the Mid-Atlantic Ridge, East African Rift Valley, Andes Mts. of So. America & Cascade Range of the Pacific NW, the Himalayas, and the San Andreas Fault.
* How does plate tectonics relate to the global distribution of earthquakes and volcanoes?
Part II
VI. Structural Deformation & Earthquakes
Earth Structures and Rock Deformation
Distinguish the key characteristics of the following deformational styles: elastic, brittle, ductile
Distinguish the three fundamental deformational regimes based on the orientation of principle stresses in each regime, and identify the structures and plate boundaries likely to be associated with each stress regime
Be prepared to identify the following earth structures based on sketches, geologic maps or cross-sections or verbal descriptions: extension joints, columnar jointing, sheeting (exfoliation) joints, dip-slip faults (normal, thrust, and reverse) vs. strike-slip faults (right- or left-lateral), folds (anticlines vs. synclines; hingelines and hinge planes), and deformational fabrics. It is especially useful to study sketches and other images of these features.
How do geologist express the orientation of planar structures such as beIDing, foliations, or faults (i.e., how are strike and dip defined?)
Earthquakes
What causes earthquakes? (Elastic Rebound Theory)
What type of fault tends to produce the largest earthquakes (thrust or reverse > strike-slip > normal).
Associations between earthquakes and plate boundaries (deep focus earthquakes in Benioff Zones associated with subduction; shallow focus quakes and rift zones).
Difference between focus and epicenter; significance of each.
How are earthquakes measured and how is magnitude determined? Significance of the logarithmic earthquake magnitude scale.
Difference between P-waves and S-waves, and how different travel times are used to locate the epicenter of an earthquake.
Contrast Magnitude Scale and Mercalli Intensity Scale – how is each defined? What is each good for?
Understand the following earthquake hazards and how to minimize earthquake risk: ground shifts, landslides and liquefaction, structural collapse (what factors in the construction and design of buildings contribute to risk of collapse?), fire, tsunami.
What factors influence earthquake hazards, especially those that we can control, influence or plan for.
Be familiar with general principles of earthquake-resistive construction and design.
How successful has earthquake precition attempts been? What potential earthquake precursors have scientists studied? What kind of earthquake is most predictable? (aftershocks)
Contrast the concept of long-term earthquake forecasting with that of short-term prediction. Which approach has been most successful? What are the basic principles of quake forecasting?
VII. Rivers and Floods – Ch. 14
Be prepared to recognize or define the following terms:
Gaining stream Losing stream Point vs. mean velocity Discharge
Hydraulic Radius Turbulent vs. Laminar flow Stream Capacity vs. Competence
Graded Stream Base Level Point Bar Cutbank
Natural levee Recurrence Interval
How does the balance between infiltration and runoff affect the probability of flooding in a given area? What factors affect this balance (especially those factors that may be influenced by engineers or other human activity)
How is groundwater related to surface water?
What are the basic variables affecting stream processes, and how are these parameters interrelated? I.E., How do they mutually control each other?
What steps can an engineer take to control erosion during development?
How does the concept of dynamic equilibrium as expressed in the idea of the graded stream assist in predicting how a stream system is likely to react to a change in one of its fundamental parameters? Be prepared to predict how a stream would react to various common engineering modifications.
How do dams affect stream equilibrium? What are some of the reasons for building dams, and what detrimental effects are commonly associated with them? What factors influence reservoir life-expectancy? Economically, why is it important that this forecast be accurate?
How do meanders evolve through time? Explain lateral erosion, cutbanks and point bars and stream cutoffs.
How are floods measured? How does flooding differ in a headwaters stream vs. a major trunk stream?
What is the recurrence interval concept as applied to floods? How are recurrence intervals estimated, and how much faith can the engineer place in recurrence intervals forecast in this fashion? Can changes in a drainage basin such as urbanization or forest clearance affect recurrence intervals and flood behavior of a stream?
Why have engineers in recent years begun to move away from the “hold by levees” strategy of flood control that has typified American flood control efforts over much of the past century? How do flood control measures such as “channel improvements” (i.e., straightening and deepening stream channels) and levee or flood wall construction affect stream behavior? How does over-reliance on these strategies lead to “arms races” between neighboring communities along a river course? What other flood control strategies are possible?
Review the history of the 1913 Great Dayton Flood, including the circumstances that aggravated the flood and how Arthur Morgan’s flood control plan aIDressed these problems.
Part III
VIII. Soils Hazards – p. 375-292
Expansive Soils (see also clay minerals in Ch. 3
Liquefaction (see also earthquakes)
Induced Subsidence – see also groundwater (below)
IX. Mass Movement and Slope Instability- Kehew, Ch. 13
Understand the classification of mass movement processes.
Be prepared to recognize the following types of mass movements based on images or written descriptions: Falls, topples, slumps, planar rock slides, creep, debris flow, earth flow, mud flow, rock or debris avalanche, and complex slope failures.
Be able to recognize the landscape clues to creep or solifluction.
Understand the basic concept of slope instability as a function of the ratio of driving forces (gravity) to resisting forces. Be able to define Factor of Safety.
Understand the geometric (trigonometric) conditions that define the stability of a block on a plane relative to the slope of the plane for sliding and overturning, respectively.
Be prepared to discuss how parameters such as material strength, orientation of planes of weakness, and elevated groundwater pressures affect slope instability.
Understand basic concepts and approaches to slope stabilization for rock slopes and soil slopes.
X. Groundwater – Kehew 11 & 12 (esp. 11)
Basic controls regulating the balance between infiltration & runoff (e.g., plant cover, precipitation intensity, slope, infiltration capacity).
Recharge vs. Discharge, and how the balance between them controls the level of the water table.
Key terms: Saturated vs. Unsaturated zone, aquifer, aquitard, confined vs. unconfined aquifers, artesian aquifers, water table, and potentiometric (piezometric) surface.
Aquifer Types: Alluvial Valley, Buried Valley, Coastal Plain, Tectonic Valley, Bedrock, & Karst. Be prepared to recognize from sketches and describe potential problems.
Darcy’s Law: Q/A = K DH/L
Knowing Darcy’s Law implies knowing the mathematical definitions of: hydraulic head (including elevation head and pressure head), hydraulic gradient, and hydraulic conductivity,
You should expect a problem that will require you to calculate both the Darcy Flux (vd), the seepage velocity (i.e., linear velocity) (vx), and/or the travel time for flow in an aquifer. You should know the difference between Darcy flux and seepage velocity, and how to calculate one from the other if given the porosity.
Be prepared to predict groundwater flow direction and calculate hydraulic gradient from a contour map on the potentiometric surface (or water table) of a given aquifer.
What is a cone of depression, and what parameters would control the size of the cone of depression that would be developed by producing water from a given well.
Societal & Engineering Issues involving Groundwater:
“Groundwater mining” and Induced Subsidence
Groundwater Contamination – What is a contaminant plume? Understand basic concepts for predicting contaminant transport and basic approaches to containing, capturing, and treating contamination. What are the important factors to consider concerning the nature of the contamination? (e.g., point source vs. nonpoint source, aqueous vs. nonaqueous, denser or less dense than water?)
What are the main prevention, treatment or remediation approaches for groundwater contamination? (e.g., containment, pump and treat, air stripping, bioremediation, etc).