Structural Geology 1. Briefly interpret the contact in red indicated by the arrows in the sketch at right. What kind of contact is this, and what are the relative age constraints on when it formed? Way Up Miocene Oligocene Eocene Paleozoic metamorphic rock 2. Briefly indicate the most likely interpretation of the red contact indicated by the arrows in the sketch at right. What kind of contact is this, and what are the constraints on when it formed? Way Up Cenozoic strata Paleozoic strata 3. The image at right is part of Grady Konzen’s structure contour map on the top “Big Injun” formation along the Ohio River east of Marietta. The reds represent higher elevations, the yellows and greens lower. Briefly describe and interpret this structure, including the type of fold illustrated, the type of fault illustrated, and the significance of the offset fold hingeline (i.e., is this a cutoff or a piercing point, and what is the significance of that distinction?) 4. What type of fault and what type of fold are illustrated by the image at right? Briefly describe the progressive development of this fault-fold system. 5. What type of fault and what type of fold are illustrated by the image at right? Briefly describe the progressive development of this fault-fold system. 6. The GoogleEarth view at right shows the orientation of vertical joint systems at Arches National Park in Utah. What would have been the orientation of the least principle stress (3) at the time the joints formed? Use arrows to draw and label the orientation of 3 on the image. [Type here] N [Type2 here] [Type here] 7. Compare and Contrast pure shear vs. simple shear deformation histories being careful to address how material lines in various orientations rotate during the deformation history and how the finite strain axes change with respect to the incremental strain axes. 8. Assuming the fracture systems illustrated at right all formed under the same state of stress, name and interpret the origin of the green vs. the blue joint systems. Also, add and label arrows illustrating the greatest and least principle stress orientations and the expected resolved shear stresses on the conjugate systems 9. What kind of sedimentary structure is illustrated in this image, and what is the stratigraphic facing direction (“way-up”) in this picture, and how do you know? [Type here] [Type3 here] [Type here] 10. Assuming the bedding in the image above was turned on end by folding, which of the sketches at right shows the correct interpretation of the geometry of the first-order fold? Briefly describe how you figured it out? 11. In the image at right, why is cleavage in the sandstone steeper than the cleavage in the slate, and what is this phenomenon of changing cleavage orientation called? 12. The images at right shows two alternative interpretations of the first-order fold geometry from the bedding-cleavage relationships in the same sandstone-slate sequence illustrated in the previous question. Which interpretation is correct and why? 13. Briefly describe the symmetry and vergence direction of these folds. [Type here] [Type4 here] [Type here] 14. Based on the illustrated dip isogons, which Ramsey fold class do the folds illustrated at right belong to, and how do you know? 15. Would the Ramsey fold class illustrated in the above be more likely to represent flexural slip or passive flow folding? Explain. 16. Assume the thin, wavy black lines represent parasitic fold relationships in an outcrop. Which of the two interpretations illustrated would be more likely to represent the first-order folds in the vicinity of this outcrop? Briefly explain how you figured this out. 17. Briefly name, describe and interpret the fold interference pattern illustrated at right. Using MS drafting tools, add and label first and second generation fold hingelines (3 pts) 18. Describe two different ways that original bedding (S0) could become transposed into a new orientation. [Type here] [Type5 here] [Type here] 19. Name the structure illustrated at right and indicate the shear-sense with shear-sense arrows. 20. The photomicrograph at right is a muscovite bearing quartzite under crossed polars with gypsum plate inserted. Use MS drafting tools to label the S & C planes and shear-sense direction on the photograph. Also, what is the significance of the mica clasts? Briefly describe the origin and significance of these structures 21. The figure at left is a quartz c-axis pole figure from the same sample illustrated in question #32. Use shear-sense arrows to indicate the sense of shear based on the pole figure. Briefly explain why crystallographic preferred orientations form in deformed metamorphosed rocks. [Type here] [Type6 here] [Type here] 
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