GEOL 1311 Earth Science Lab 4 – Structures and Geologic Maps

Key Questions:GEOL 1311 Earth ScienceLab 4 – Structures and Geologic Maps• What shapes do rock bodies take in the Earth?• How do two-dimensional visualizations of the Earth, such as maps and cross-sectionsrelate to the three-dimensional Earth?At the end of this lab you will be able to:• Describe the main types of geologic structures we see on the Earth.• Read geologic maps.• Be able to predict surface geology based on cross-sections of the Earth and vice-versa.PART I. Working with 3D Geologic BlocksCredits: These exercises are modified from: The Hidden Earth Project, led by Dr. StevenReynolds, Arizona State University (http://reynolds.asu.edu/blocks/103_home.htm)Background Information:In this module, you will learn about five major geologic features - layers, folds, faults, intrusions,and unconformities. These five features intersect surfaces in various ways due to geologic eventsthat continually occur below the surface. Throughout the module, you will interact with moviesto learn how geologic events such as tilting, deposition, erosion, and faulting change and modifythe appearance of these five features on the surfaces of blocks. After interacting with thesemovies, you will be able to identify and recognize the five main features and reconstruct thegeologic history that resulted in the complex pattern of surface features found in these blocks.Directions:Open the file for 3D Geologic Blocks in a web browser as directed by your Teaching Assistant.Follow the directions on the screen and fill out the attached worksheets as appropriate.Lab 4: Structures and Geologic Maps1UTEP GEOL 1311 Earth Science I

Name ________________________________ Geologic Blocks: 103 WorksheetL-1 Sketch L-2 Sketch L-3 SketchF-1 Sketch F-2 Sketch F-3 Sketch

Name ________________________________ Geologic Blocks: 103 WorksheetDirection of faulting:Visual clues used:Ft-1 Describe Ft-2 Sketch I-1 Describe1.2.3.4.I-2 List Order of Events (old to young)s (old U-1 Sketch

Blocks Module Student GuideIn this module, you will learn about five major geologic features - layers, folds, faults,intrusions, and unconformities. These five features intersect surfaces in various ways due togeologic events that continually occur below the surface. Throughout the module, you willinteract with movies to learn how geologic events such as tilting, deposition, erosion, andfaulting change and modify the appearance of these five features on the surfaces of blocks. Afterinteracting with these movies, you will be able to identify and recognize the five main featuresand reconstruct the geologic history that resulted in the complex pattern of surface features foundin these blocks.The movies included in this module are QuickTime Virtual Reality (QTVR) movies andallow you to click-and-drag the mouse to change features in them. Above each movie, arrowswill indicate the direction(s) you can move the mouse and text will indicate what changes willoccur as you click and drag the mouse. Most sections begin with rotating movies so you cansee the four sides and top of a block. These movies can be rotated by clicking and dragging themouse from left to right (or right to left). The slower you drag the mouse, the smoother thechanges will be. Other movies allow you to change two features at a time. For example, somemovies let you rotate a block (clicking and dragging side-to-side) as well as making the blockpartially transparent so you can see features beneath the surface (by clicking and dragging upand-down).For movies with two changes in them, dragging the mouse diagonally will causeboth changes to occur simultaneously. To prevent this, try to drag the mouse horizontally andthen vertically (or vertically and then horizontally). Note: You can also use the arrow keys onthe keyboard to make these changes occur and have more careful control over the changes.Other movie types in this module allow you to:cut into a block (from the left, from the right, and from the top) so you can see how aprocess such as erosion would change the surface of a block.offset the fault to observe how layers or folds would appear to change after faulting occurs.You can also simulate erosion by cutting into the blocks, rotate the blocks, and changethe amount of transparency.reveal the unconformity to see the boundary between old and young rocks (where there is alarge gap in time in which no distinct events occurred).While progressing through this module, you will be asked to complete various activitieson worksheets. Questions on the worksheets will ask you to: sketch a missing face of a block;sketch a block after imagining it has been cut into; sketch a face of a block after it has beenfaulted; describe the differences between types of faults, how they change features, and how theycan be recognized in the field; list geologic events in the order they occurred; describedifferences in types of intrusions; and draw unconformities. Make sure you have the worksheetfor each section before you begin.This module was designed to help you form your own definitions of terms andprocedures. For this reason, answers will not always be provided for confirmation. The same istrue of the application questions at the end of each section. Try to formulate your own answerson your own or in your group before asking your teacher for help.

Use the Quicktime movie that illustrates strike and dip to help you with the following fordiagrams.1. Draw three horizontal layers. 2. Draw three vertical layers.The dip of these layers is_____ºThe dip of these layers is_____ºThe direction of dip is _______The direction of dip is _____3. Complete this block. 4. Complete this block.a b c dNN45º 450660ºThe strike of these layers is______The strike of these layers is_____The dip (direction and angle)of these layers is______The dip of these layers is_____The oldest layer is________Lab 4: Structures and Geologic Maps5UTEP GEOL 1311 Earth Science I

Background Information:PART II. Working with a Geologic MapGeological maps represent 3D geology on a 2D surface – similar to regular maps.The different colors on a geologic map show different rock formations. Formations are packagesof rocks of the same type and age that are distinct from surrounding rocks.Elements of a Geological Map:• Legend• Scale• Stratigraphic columnThe following symbols are used to denote geologic periods:Pc – Precambrian (4,500 to 543 mya)C -- Cambrian (543 to 490 mya)O – Ordovician (490 to 443 mya)S – Silurian (443 to 417 mya)D – Devonian (417 to 354 mya)M – Mississippian (354 to 323 mya)P – Pennsylvanian (323 to 290 mya)P – Permian (290 to 248 mya)T -- Triassic (248 to 206 mya)J -- Jurassic (206 to 144 mya)K – Cretaceous (144 to 65 mya)T – Tertiary (65 to 1.8 mya)Q – Quaternary (1.8 mya to today)• Contacts: Contact lines are heavier, and separate different rock units.• On a geologic map, faults are shown as solid lines, and the dip is usually given.• Rock units on a map will have one of the preceding letters as the first part of the symbolfor the rock unit; the second part will be part of the formation name. For example, Kfmeans “Cretaceous Finlay (limestone),” while Qal means “Quaternary alluvium.”Lab 4: Structures and Geologic Maps6UTEP GEOL 1311 Earth Science I

Directions: Answer the following questions using the geologic map of Texas.1. Describe, in words, the color pattern on this map. What do you see?2. What is the oldest rock unit on the map? Write out its name AND its symbol.3. What is the youngest rock unit? Write out its name AND its symbol.4. How are faults shown on this map? Draw some of the symbols.5. If you follow I-35 from Dallas to San Antonio, you are following the Balcones Escarpment.What is the Balcones Escarpment? HINT: use the cross section on the back labeled U2-U3.6. What kind of rocks are the TV formations between El Paso and Alpine?7. As you drive from Fort Worth to Big Spring, do the rocks get older or younger?Lab 4: Structures and Geologic Maps7UTEP GEOL 1311 Earth Science I

8. As you drive from San Antonio to Corpus Christi do the sediments get older or younger?9. Look at cross section F-F1. Locate the Live Oak Creek area and look in the pC formation tolocate the vertical fault. Estimate the amount of displacement on the fault in the pC.10. Look at cross sections E-E1. Locate the (green) Cretaceous rocks and follow them with yourfinger from the Fort Worth Basin to the Louisiana border. How many and what type of geologicstructures do you see?11. Look in the explanations to find the Precambrian rocks; find the pink granites and the brownmetamorphic rocks. How many places in Texas are they exposed at the surface? What kinds ofrock (igneous, metamorphic, sedimentary) are most exposed in Texas?Preparing for the Lab Quiz• Practice with 3D blocks at http://reynolds.asu.edu/blocks/103_home.htm.• Given a diagram of any geologic structure, are you able to identify the structure (e. g.anticline, syncline, normal fault, reverse fault, strike-slip fault?• For diagrams of faults, can you identify direction of motion with arrows?Lab 4: Structures and Geologic Maps8UTEP GEOL 1311 Earth Science I