Exams will be returned 15 minutes before end. RESULTS: A: B: C: D: F: % of class got As and Bs CONGRATS! % got a D or less If your grade is what you want, keep up the good work! If not, see me for advice. OFFICE HOURS: M/W 1-2; T/Th 11-12 or by appointment Comprehensive Final Exam This exam is optional if you take it, it will replace the lowest of these equally weighted grades: Total Quiz Average, Exam 1, Exam 2 Note: It cannot replace your grade for Exam 3. Remember, your grade is determined by the average of four grades: Exam 1, 2, 3, and Quiz Average. The Comprehensive Final replaces the lowest of those 4 (even if your grade on the comprehensive exam is lower! So don t take it unless you know you ll do better!) The content for the optional comprehensive exam comes ENTIRELY from the Pass Sheets for Exam 1 and 2. To decide if you should take the optional comprehensive final exam, please come see me during office hours or by appointment to run your numbers and see how it will help. If you decide to take this exam, you will do so on the same day and time as Exam 3 (or IF you make arrangements personally with me ahead of time, you can take it any other time I offer exams during Finals Week). Like all exams, pass sheets are required tickets for entry! WARNING!! Don t let the comp final prevent your studying for Exam 3. EXAM RETURN Most important! You cannot keep the exams. You may keep only the Pass Questions portion. Please return rest to me before you leave the room! EXAM RETURN If you would like to review the exam further AND/OR ask questions on the exam AND/OR ask questions on the grading AND/OR discuss ways to improve PLEASE COME BY MY OFFICE!! EXAM RETURN Grades are posted in hallway display case outside S45 (lab room). Please review for accuracy. Listing is ordered by grade, and each student is identified by the last 4 digits of your student number. I dropped your two lowest quiz scores already! 1
Turbidite Beds in Zumaya, Spain Which came first? Trinity Alps Northern California 2
Disconformity Erosion of Sedimentary Rocks 3
Eroding Metamorphic Rocks Turn to Neighbor: Explain Pictures How does each form? Unconformities ANIMATION 4
Grand Canyon Stratigraphy Erosion in progress Kaibab Limestone Toroweap Formation Coconio Sandstone Grand Canyon Stratigraphy THE GRAND CANYON 360 Ma Limestone (Redwall): Thin-bedded, fine-grained limestone; cliff-forming; marine fossils Setting: Marine deposits, far from shore, <300 ft deep Hermit Shale Supai Group Disconformity 390 Ma Limestone (Muav): Thin to thick-bedded, mottled limestone; cliff-forming; marine fossils Setting: Marine deposits, far from shore Redwall Limestone Disconformity Muav Limestone Bright Angel Shale Tapeats Sandstone Angular Unconformity 500 Ma Shale (Bright Angel): Thin-bedded mudstone and find-grained sandstone; slope-forming; marine fossils Setting: Marine deposits, off-shore Tilting Unkar Group 504 Ma Sandstone (Tapeats): Coarse grained (pea-sized) sandstone and conglomerate; cliff-forming Setting: Marine, near-shore beach and sand bar Nonconformity Zoroaster Granite Vishnu Schist 1.6 Ga 1.3 Ga Granite (Zoroaster): Pegmatite Setting: Deep under Continental Volcanoes likely Subduction zones Schist (Vishnu): 5
The Great Unconformity Zoroaster Granite (shot through with pegmatite veins) and Gneiss underlying a horizontal sandstone layer The Grand Canyon The Great Unconformity Zoroaster Granite (shot through with pegmatite veins) and Gneiss underlying a horizontal sandstone layer The Grand Canyon Pegmatite Zoroaster Granite (shot through with pegmatite veins) The Grand Canyon X-Sxn A Stratigraphy Basalt dike A Limestone Sandy limestone Lithic sandstone Conglomerate Dis/nonconformity Reverse fault Basalt dike B Granite Shale B Sandy shale Quartz sandstone Arkose Shale A 6
X-Sxn B Stratigraphy Erosion in progress Glacial till Siltstone Shale Sandstone or Dike Lava flow Angular unconformity Tilt A E B C F X-Sxn C Stratigraphy Erosion in progress, by river that is still present SSC Angular unconformity Tilting SSB Disconformity Siltstone Limestone Basalt Sandy shale Angular unconformity Granite or Normal Fault A Granodiorite or Tilt Reverse Fault B Sandstone Shale Conglomerate SSA Transgression / Regression ANIMATION 7
3.5-Million-Year-Old Fly in Amber Saber-Toothed Cat Skeleton 8
Ancient Worm Burrows Footprint in Volcanic Ash Review Week 1 Geologic Time Scale & Earth History 9
Division Begin End End Event Cenozoic 65 Ma Present Mesozoic Paleozoic 245 Ma 570 Ma 65 Ma 245 Ma Mass extinction (including dinosaurs) Mass extinction Precambrian 4.6 Ga 570 Ma Hard parts Action/Environment Order Action/Environment Order Dinosaurs first appear Trilobites first appear 12 9 Earliest evidence of photosynthesis Earth formed 5 1 Earliest evidence of life with hard parts 8 Opening of Atlantic ocean (Pangea breaks up) 14 Earliest evidence of multicellular life 7 Dinosaurs go extinct 16 Earliest evidence of life moving onto land 11 Earliest evidence of life (prokaryotes) 4 Pangea came into existence. Oceans first appear (water) Mammals first appear 13 3 15 Earliest evidence of rocks (hard crust) Eukaryotes first appear (nucleus in cells) Fishes first appear 2 6 10 10
START 90 Th 232-6 alpha particles -6 (2 n + 2 p+) -12 n 12 p+ # Halflives 1 Fraction of original Parent remaining ½ Fraction of original parent turned into daughter ½ Parent:Daughter ratio 1:1 78 Pt 208-4 beta particles -4n + 4 p+ 2 3 ¼ 1/8 ¾ 7/8 1:3 1:7 END 82 Pb 208 Radioactive Decay Worksheet Review on own at home! 4 5 6 1/16 1/32 1/64 15/16 31/32 63/64 Radiometric Dating Worksheet Review on own at home! 1:15 1:31 1:63 11
P:D Ratio = 1:3 Therefore, # half-lives = 1 Half-Life = 10,000 years Therefore, how old is rock? 20,000 years old! 2 Turn to Neighbor: Solve this problem Ratio of Parent to Daughter in a rock is 1:1. Half-Life of Parent Daughter pair is 1 m.y. How old is the rock? Explain Open and Closed Systems What does the date of an igneous rock mean? What does the date of a metamorphic rock mean? What does the date of a sedimentary rock mean? 12
Parent (P) Daughter (D) Half-lives (T 1/2 ) Materials dated U-238 Pb-206 4.5 x 10 9 yr Zircon (igneous rocks) U-235 Pb-207 0.7 x 10 9 yr Zircon (igneous rocks) K-40 C-14 Ar-40 N-14 1.4 x 10 9 yr 5700 yr Micas, volcanic rock (igneous, metamorphic rocks) Shells, limestone, organic materials We have now completed this week s question sheet. On your own, review each question again. I recommend that you write out your answers (synthesize your thoughts and notes and put the answers into your own words). If something doesn t make sense or to just get some feedback, come see the tutors or me during my office hours. Remember: half of next week s quiz will contain any question from the question sheet. 13
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