Compare & contrast the two basic categories of sedimentary rocks..
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 addition, 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 additional, 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?
Compare & contrast the two basic categories of sedimentary rocks.
