Rocks list the rock names associated with each

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rocks, list the rock name(s) associated with each tectonic setting or depositional environment, and list the geologic region to which that rock assemblage belongs. Hint : As you are identifying the rocks, recall the processes you went through in the Igneous, Sedimentary, and Metamorphic Rock Labs. Distinguish between igneous, sedimentary and metamorphic rocks using their characteristic textures. Use the rock identification charts to name the rock samples based on their composition and texture. Rock Tray Rock Identification What rocks are commonly found in this geologic region? Geologic Region of Washington A Volcanic islands on the coast: Sediments deposited in offshore basin: Subduction-related metamorphic rocks: B Ancient continental crust (craton): C Sediments eroded from mountains after terrane accretion stopped: D Collision-related metamorphic rocks: Intruded plutons: Submarine fan sediments: E Igneous flows from rifts: F Subduction-related volcanic rocks: Sediments derived from volcanic arc: G Arc volcanic rocks: Intruded plutons: H Sediment deposited: Bedrock exposed by erosion: I Volcanic island arc: Marine sediments: Metamorphosed mantle rocks: Intruded plutons: Sediments that covered terrane:
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Lab #8: Geology of Washington 116 Homework Activities Understanding Geologic Maps The different rocks of the various terranes you have explored in today’s lab are spread out around Wash- ington State. To create a geologic map of Washington, geologists explored the entire state and determined the location, type, and age of all the rocks, as well as other significant geologic features. Instead of having to go out and find the rocks ourselves, we can use this geologic map to interpret where those different terranes and rocks are found today. Activity 1: Basic Map Reading Colors are used to differentiate rock units on geologic maps, and each map has a slightly different color scheme. Refer to the map legend to determine the name and age of each rock unit. Hint : Notice that there are five major groups. Each group uses a different color to distinguish it from the others, and the units within each group use different shades of that base color. 1. Name the major groups. ____________________________________________________________________ __________________________________________________________________________________________ 2. What do the labels mean (e.g. Tertiary, Mesozoic, etc.)? ___________________________________________ __________________________________________________________________________________________ 3. Within each group, can you tell which rocks are older and which are younger? Use the geologic time scale to in - terpret the relative age. _______________________________________________________________________ __________________________________________________________________________________________ Activity 2: Using the Legend and Locating Rocks 1. a. From the legend, what is the abbreviation for the Columbia River Basalts? ____________________________ b. What does each letter in that abbreviation stand for? ____________________________________________ c. Which quadrant of the map (NW, NE, SW, or SE) is dominated by this rock type? ____________________ 2. a. What is the abbreviation for the other rock type that also commonly occurs in this area? ________________ Hint : Its map unit color is beige. b. Which is older, the beige unit or the Columbia River Basalts? Explain your reasoning. _________________ ________________________________________________________________________________________ c. Look at the description of the beige unit in the legend. This unit is associated with the terrane discussed on page 112. What event do you think deposited this unit? Explain. ___________________________________ ________________________________________________________________________________________ ________________________________________________________________________________________ 3. In which region (W-SW, N-NE, or S-SE) are the oldest rocks (Precambrian and Paleozoic) found? _____________ 4. Find the pre-Cretaceous metamorphic rocks (light purple) and Mesozoic intrusive rocks (pink).
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