1 ES202 Lab 3 - Sedimentary Rock Analysis and Classification Update Jan 21, 2012 Part 1 A. Cambridge Intro Rock Video Questions (ROCKSandMINERALS_cambridge_science.mpeg; Time Mark: 12:40) 1. What is the definition of a “rock” 2. What are the three basic types of rocks? 3. How do igneous rocks form? 4. How do extrusive or volcanic igneous rocks form? 5. How do intrusive or plutonic igneous rocks form? Provide a common example of an intrusive rock? 6. What are sedimentary rocks? Where do they form and why? 7. List four types of surface environments in we find sediments that form sedimentary rocks? 8. What are the two types of sedimentary rocks? 9. In detrital sedimentary rocks, what is the difference between gravel, sand, silt and clay? What is the distinguishing characteristic? 10. Provide an example of biochemical or chemical sedimentary rocks. How are chemical rocks classified? (End Video on Time Mark 18:53) Part 1B. Sedimentary Rock Video Exercise (Earth Revealed: Sedimentary Rocks) Watch the video in the lab and answer the questions below. 1. Who first explored the geology of the Grand Canyon? How did the Grand Canyon form? 2. How many years of Earth history are contained in the sedimentary rocks of the Grand Canyon? 3. What is the general goal of sedimentary geology? 4. What is sediment? How is it formed? 5. List and describe 3 examples of loose sediment at the Earth’s surface. 6. How is loose sediment transformed into hard sedimentary rock?2 7. True or False: sedimentary rocks most commonly occur inside the Earth, while igneous rocks are common at the Earth’s surface. Explain your answer. 8. Define the term “clastic”. 9. What is the smallest size of sediment particle called? What is the largest size of sediment particle called? 10. List and briefly describe 2 examples of how sediment may be transported at the Earth’s surface. 11. List and describe 3 places at the Earth’s where you would likely find sediment deposits. Why do you find deposits in these places? 12. Define the term “lithification”. What are 2 processes that result in lithification of sediment? 13. List and describe 2 environments where chemical sediments may form. 14. What is the name of a sedimentary rock that forms from the skeletons and hard parts of dead sea animals? 15. Where does coal form? What is coal composed of? 16. What is the motto for the “principle of uniformitarianism”? What is the principle of uniformity and how is it used to interpret Earth history? End Video at Uniformitarianism. Part 2. Recognition of Sedimentary Process (refer to 9th Edition of AGI Lab Manual) 1-1. Based on your pre-lab questions and p. 130 of your lab manual, match the sedimentary process term on the right with the sedimentary rock on the left. _____1. Sandstone A. Detrital Origin (weathering / fragmental) _____2. Conglomerate B. Biochemical (biologically-derived rock) _____3. Shale C. Chemical (Physical-Chemical Process) _____4. Rock Gypsum _____5. Coral Reef Deposits _____6. Sand on the beach _____7. Bonneville Salt Flats of Utah _____8. Shells on the beach _____9. Coal _____10. Breccia3 Part 3. General Questions on Sedimentary Texture 2-1. Using the attached grain size chart and the Wentworth scale, determine the grainsize of the following detrital sedimentary rock samples (derive the grainsize to the level of fine sand, medium sand, etc.)., and determine the sorting (well sorted, moderately sorted, poorly sorted). Sample No. Grainsize Sorting (list ~diameter and term) 11 _________________ _________________ 9B _________________ _________________ 15 _________________ _________________ 4 _________________ _________________ 6 _________________ _________________ 14 _________________ _________________ Sample Jar S2-1 _________________ _________________ Sample Jar S2-7 _________________ _________________ 2-2. Compare and contrast the sedimentary texture of sample 11 and sample 4. Which one do you think has sediment that was more greatly transported during it's formation? 2-3. Observe the characteristics of sample 35. Is this detrital or biochemical? What is this specimen? 2-4. Examine the deposit in the beaker labeled "2-4". Explain how this deposit formed. Is it chemical or detrital?4 Part 4. Sedimentary Rock Identification Using the sedimentary rock analysis and identification key on p. 129 and p. 131 of the lab manual, complete the table on the following page. Sample Number Detrital, Chem., or Biochem? Composition: choose all that apply: quartz, feldspar, clay, plant frags., calcite, halite, gypsum, iron minerals Grain Size (for detrital) / Crystal Size (for chemical / biochemical) Other Characteristics (e.g. fossils, grain shape, fizzes with HCl, scratchable, taste, etc.) Rock Name 30 1B 14 9B 11 8 3 13 31 32 20 16 2 7 15 12 10 6 4