November 3, SWABT interpret cross-sections with index fossils and unconformities to determine relative ages of rock layers.

Transcription

1 Aims: November 3, 2016 SWABT interpret cross-sections with index fossils and unconformities to determine relative ages of rock layers. Agenda 1. Do Now 2. Class Notes 3. Guided Practice 4. Independent Practice 5. Practicing our AIMS: Homework: EH.5 Unconformities How will you help our class earn all of our S.T.R.I.V.E. Points? UNIT TEST COUNTDOWN: 4 study days! 1

2 Aim Check: 2

3 SCIENCE 8 Unconformities EH.5 Name: Date: Homeroom: Earth s History Shoooo I m GROWN! OBJECTIVES: By the end of class, students will be able to SWABT interpret cross-sections with index fossils and unconformities to determine relative ages of rock layers. DO NOW 1. The picture shows a rock formation with folded layers. Which statement best explains how the rock layers folded? A. The rock melted and flowed downhill. B. The rock was deformed by a meteorite impact. C. The rock was suddenly pulled apart during an earthquake. D. The rock was slowly compressed due to tectonic plate movement. 2. What would this collision do to the strata? How could this affect the Law of Superposition? The cross section below shows the movement of wind-driven sand particles that strike a partly exposed basalt cobble located at the surface of a windy desert. 3. What would this process do to the strata? How could this affect the Law of Superposition? 3

4 CLASS NOTES DRAKE <3 s GEOLOGY... LAW OF SUPERPOSITION INDEX FOSSILS Fossils can tell the relative age of the rock layer and o o Easy peasy, but what about when the layers look like this? 4

5 HUTTON still kinda a big deal While developing his idea of Hutton became very interested in the rock outcrop shown below. He soon realized that according to uniformitarianism, the lower rocks must have been: Therefore, there must be some period of time that is NOT represented between the formations of these two units! UNCONFORMITY: 5

6 DISRUPTIONS EXTRUSION : Younger than rock below it INTRUSION: FAULT: younger than layers it goes through What layer is the youngest? 6

7 Guided Practice Following is a description of the geologic history of a region. A large sea covered the region, allowing coral reefs to develop. Next, the sea retreated and the region became desert. Then, geological stresses caused surface rocks to crack and break. Finally, the deep cracks in the surface rocks allowed lava to erupt and extrude, which then quickly cooled. The layers M, N, and O represent the position of three rock layers found in the region. The layers have not been overturned. Select the boxes to match the geologic features or materials that will likely be found in the layers, based on the region s geologic history Layer M Layer N Layer O Fault Basalt (igneous) Limestone (sedimentary) Sandstone (sedimentary) 7

8 Directions: Answer the following questions in COMPLETE sentences. ICE to support your answer 3. Use the cross section to explain how the geologist knows that the flow labeled on the picture is older than the shale. 4. Use the cross section to explain how the geologist knows the relative age of the intrusion compared with that of the gravel. 8

9 Independent Practice Directions: For each key term, explain the big idea to a kindergartener. Then, draw a picture to illustrate the word. Term Concept Picture UNCONFORMITY INTRUSION EXTRUSION FAULT 9

10 Use the picture below to answer questions Order the layers from oldest to youngest. 2. Explain what an intrusion is and how old it is relative to the layers of rock around it. 3. How could a scientist use the fossil in layer B to date a rock layer in another location? Examine the following diagrams. Order the layers of rock from oldest to youngest. Remember it is easiest to do this by starting with the oldest (bottom) and working up to the youngest. The diagrams start simple and get beastier and beasier! 10

11 What rock is layer B made of? What type of rock is layer B? How is that rock formed? 11

12 What type of disruption is layer F most likely to be? How is that rock formed? 12

13 You Do: REVIEW! (comps are coming up faaaaast ) 1. According to the theory of uniformitarianism, A. geologic processes we observe today have operated in the past B. geologic process in the past operated at the same rate as they do today C. all of the planets formed from a uniform solar nebula D. early Earth was covered by a uniform magma ocean 2. James Hutton ( ) is often referred to as the father of modern geology. His detailed observations and theories about Earth processes opposed the accepted theories of his time. One of his contributions was the development of what he called the great geological cycle. Hutton theorized that most rocks were igneous in origin. The igneous rocks could then change into sedimentary or metamorphic rocks. The chart below shows locations of several rock types and the minerals they contain. What evidence from the chart could be used to support Hutton s theory that most rocks are igneous in origin? A. Igneous rocks are only found in Germany. B. Sedimentary rocks are found in both North America and England. C. The rocks found in the table are made up of many of the same minerals. D. The rocks found in the table are different types of rocks from different locations. 3. Which of these statements about the modern version of uniformitarianism is correct? A. Rapid change is solely responsible for Earth's features. B. Geologists no longer believe any of the concept to be true. C. It completely ignores the role of catastrophic events in shaping Earth's features. D. It includes the role of occasional, catastrophic events in shaping Earth's features. 13

14 4. Which of the following pieces of evidence would be most helpful to a historian studying the amount of rainfall at Plymouth Colony in 1620? A. a fossil B. a tree ring C. ripple marks in a rock D. an ice core 5. Catastrophism assumes that the Earth s surface was shaped by violent, short-lived natural events. Describe an example that a geologist would define as a catastrophic event. Then, explain how this event can be used to support the Theory of Uniformitarianism. 6. An unusual type of fossil clam is found in rock layers high in the Swiss Alps. The same type of fossil clam is also found in the Rocky Mountains of North America. From this, scientists conclude that A. glaciers carried the fossils up the mountains B. the Rocky Mountains and the Swiss Alps are both volcanic in origin C. clams once lived in mountains, but have since evolved into sea-dwelling creatures D. the layers of rocks in which the fossils were found are from the same geologic age 14

15 Science 8 Name: SKILL SNAPSHOT Date: EH.5: Unconformities Homeroom: Quick Notes: Read and ANNOTATE each question before you solve the problem. Like A Scholar? Yes No Redo? Yes No Directions: Support your selection by finding evidence to support your answer OR evidence to support why another is incorrect. Start your explanation with The evidence shows that Question 1. What geologic process accounts for the difference in the arrangement of the rock layers? Supporting evidence A. erosion B. intrusion C. faulting D. extrusion 2. The Law or Superposition says that A. The rock layers that are on top are less dense B. The rock layers that are on top are older C. The rock layers that are on the bottom are older D. The rock layers that are on the bottom are less dense 3. Mrs. Petrozzi claims that a fossil found is 200,000 years old according to generally accepted radioactive dating procedures. Mr. Parker disputes the accuracy of the age because the fossil was found closer to the Earth's surface than were previously discovered fossils of the same age. Which of the following should Mrs. Petrozzi use as evidence to support her finding? A. Fossils form only under certain conditions. B. Older rock layers may be pushed closer to the surface by geologic processes. C. Older rock layers commonly lie deeper underground than younger ones. D. The age of a rock layer can often help in determining the age of the fossils it contains. 15

16 4. The picture below shows a geologic cross-section of rock layers in a specific area. KEY W = intrusion X = silt layer Y = unconformity Z = sandstone layer Feature W represents an intrusion. Choose two other labeled features/layers in the geologic crosssection and identify their relative age with relation to intrusion W. Support each answer with specific information about the cross-cutting relationship from the crosssection. 5. The magnified views shown of the minerals found in an igneous rock and in a metamorphic rock. The millimeter scale indicates the size of the crystals shown in the views. Identify the environment of formation of the igneous rock based on the size of the crystals. Then, explain how grain size supports your conclusion. 16