how to draw strike lines on a geologic map

Below is a diagram explaining strike and dip. Give the . Navigate to "Add XY Data" Figure 4. Although the two-dimensional map-view is useful, one of a geologist's key tasks is to infer the type and orientation of rocks in the subsurface. A line called Strike line joins these two points. The contours are so detailed on the topographic map that you can just use every other contour to construct your profile. Finally add some code to draw a line from the coordinates for the dip lines. Below is a geologic map showing the position of two outcrops in which the attitude of bedding was measured (Figure 12). On a geologic map, this is represented with a short straight line segment oriented parallel to the strike line. 2. I have attached a link of an image where you can see a pink outcrop displaced by a fault over almost 80km. Here, simply click the Save button on the toolbar or go to \\Model\Save, and then close the window. You can also write some code to draw the strike line. Sawteeth on upper (tectonically higher) plate. b. Answer: Drawing Strike Lines A strike line is drawn by connecting the locations or points where the same set of lithological contacts intersect different parts of the same contour. Figure 7. Set the label offset to be 2 points, measured from the feature geometry. strike-slip faults in map view) to show thrust offset. (4x3) 3c Draw a line through the radio tower showing the orientation of a vertical cross section Table of Fold Symbols. (3) Use fold line technique shown in e.g. a. Strike and dip are a way of representing the three-dimensional orientation of a planar surface on a two-dimensional map. First, let's look at how you can get a strike and dip measurement from a map symbol. dtr changes degrees to radians. I would like to draw a geologic map with contours (representing the outcrops) and a line (representing the strike-slip fault). In addition you will be drawing and reading standard geologic map symbols for faults, folds, and strikes and dips. If the plane is curved (e.g. the map pattern. Dip is the angle that a bed or layer plunges into the Earth from the . To draw your line, use the Interpolate Line button and start clicking out a . [SE] The beds on the west (left) side of the map are dipping at various angles to the west. B Lines of strike can be determined by locating where a contact intersects a given contour line in more than one point; these points of intersection lie along strike. Strike: The compass bearing of an imagined horizontal line across a plane. Indicate the strike of the darker bed on the geologic maps shown below in Fig. Use to indicate another type . Refer to the Lab Assignments Grading Rubric for a reminder of what constitutes a well-performed lab. The line of strike is the intersection between the bedding plane and the horizontal plane . Measure distances BD, DC', AA', and CC'. Strike Line Protractor Base e Step 20: In the topo view find the north-south longitude lines. These join lines are structure contours for that particular height Clue 2: Draw as many structure contours as possible to test the assumption of constant dip (planarity of surface). . 3.6 to determine . Determine the strike of each layer and enter it in the blanks above each map. The scale is the length of the dip line you would want (the bigger the area, the larger the scale). All of that is on the map's base. Geologic maps are maps that depict the rock units that crop out at Earth's surface. Show with an arrow () at each of the Fig. It is known as the system of multiple working hypotheses. Once this line AE is established, dip angle can be calculated by the following equation: 2. The long line is oriented along the strike direction. Then, count down from the primitive circle to determine the plunge. There are many other symbols and properties of geologic maps. Draw the line section (A-B) on face of the map. The intersection of a fault plane with a planar rock unit that the fault displaces produces a line called the fault cut-off or cutoff. You can also write some code to draw the strike line. On the geologic map, you must show and label the lines of strike (at least 2 lines per contact) and the strike angle. Given the elevation of 3 points on a geologic surface Begin by using the down plunge method of viewing to visualize what your cross section will look like. To determine the angle of dip . In most cases, i have seen cross-section lines that pass through dip-slip faults on geological maps and they are represented as displacement of lithologies along the fault plane on 2D cross . building a geologic map from scratch, and so many steps involving geodatabase construction and . Draw the lines joining points of equal depth on the surface. Figure 2.1 is a simplified version of the Greek Hills map (Fig. dtr changes degrees to radians. A parallel strike line is constructed wh. You may remember the technique for drawing a topographic profile from your introductory geology course (Fig. Rock units or geologic strata are shown by color or symbols. To add strike and dip symbols to your map, you need to open up the Properties - Style dialog box of your point layer, select SVG Markers and select the appropriate symbol in the Joints folder (Figure 4). Locate the symbols where you collected information to determine the strike and dip of the features. Show with an arrow () at each of the Right click the tool \\Geologic Mapping Tools\ (2) Apply Coordinate System to ESRI_Geology.gdb, and select Edit to bring up model flow chart (Fig. When measuring strike and dip from a geological map, use one contact, and . Learn to draw strike lines in order to determine the strike and dip of a unit/contacts. Geologic Maps Homework Assignment #1 1. In fact, I am a PhD student in geology. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features Press Copyright Contact us Creators . The goal here is to complete a geologic cross-section along the line A-A', which crosses the Hoback Fault in order to figure out how much offset A geologic map represents the Earth's surface as it would appear looking straight down from above, . 12-03-2015 10:46 AM. The Three-Point Problem: Graphical Solution - Modified The azimuth of strike . Geologic Maps: The Geologist's Indispensable Tool Author: James D. Myers Subject: Activity 1: Strike and Dip The dip angle for the beds is measured from the horizontal surface to the uppermost dipping bed, perpendicular to the strike line. On a profile or a cross-section, the ratio of the vertical scale to the horizontal scale, expressed as a fraction, is the vertical exaggeration . Structure contours from outcrop patterns Draw strike lines for the limestone bed Clue 1: Join points on the outcrop which share the same height. Strike and dip is a measurement convention used to describe the orientation, or attitude, of a planar geologic feature.A feature's strike is the azimuth of an imagined horizontal line across the plane, and its dip is the angle of inclination measured downward from horizontal. 1). 5). The angle of the strike is shown on each map. Strike and dip measurements of geologic features are measured using either the Move Clino iPhone app or a Brunton pocket transit. Correction for Strike and Dip Then, I would like to move (displace) the outcrops (contours) existing on the right side of the fault (line), along the fault line itself (which is not perfectly straight), so that those right outcrops join their . Step 5 Skills Practiced. The scale is the length of the dip line you would want (the bigger the area, the larger the scale). Determine true dip and apparent dip along the section. The strike is the compass direction of a horizontal line on the plane. Step 2: Draw a straight line (Strike line) along the points of intersection of bedding plane and contour line. Use medium-weight blue lines for fold hinges. Figure 11. Part 1. The geologic part consists of the black lines, symbols and . A geologic map or geological map is a special-purpose map made to show various geological features. Let's look at another example. A, Lineup the 0o-180o line of your protractor with the strike . On the Label Rotation dialog box, type 90 in the Additional Rotation box. 2 show the outcrop pattern of a single rock layer. . 1.4) from Unit 1, showing only bed F and the 300 m and 350 m contour lines. This quiz and worksheet test you on the following skills: Defining key concepts - ensure that you can accurately describe terms like geologic map and topographic map. Geological maps are typically divided into areas of different colours (for different rock units) that are bounded by lines; these lines on the map are the traces of the geological surfaces that separate the units. In the image below, the dip label has been rotated an additional 90 to line up with the symbol and has been aligned horizontally to the angle. Draw straight lines to link each photograph (A - G) with the locality (marked 1 - 15) on the map where you think it was taken. Use the Maplex Label Engine's Additional Rotation option to rotate the label to match the rotation of the dip symbol.. Where space permits mark the strike in degrees (3 figs) at the correct end of the strike line. A line connecting the points of equal elevation along the geologic contact defines STRIKE 3. Geological mapwork: using surface geology to make a geological map Match the photos to a map to see how a geological map works For each of the photographs: 1. Introduction to Geologic Mapping. By navigating to File > Add Data > Add XY Data define which column hosts the X, Y and Z coordinates and import the data as locations on the map. perpendicular to the strike line (AA' and CC') Second, draw the right triangle, BDC'. On each unit, draw the strike-and-dip symbol (you can choose either dip direction). All the horizontal lines on a plane are parallel, so they all have the same characteristic compass direction. geologists have continued to draw cross-sections, and continued the practice of using color (or patterns) to distinguish different geologic units or formations. Figure 1.4 (Greek Hills Map Area) shows a geological map with the topographic map from . 11. Viewing the results in Google Earth 3D (left) helps students visualize their constructed dip lines and the two horizontal lines they've drawn. N.B: The strike-slip fault in geology, is a plane of deformation which displaces a rock outcrop (object) horizontally (after splitting it into two parts). 2. Open ArcCatalog from the Start Menu and navigate to the file geodatabase "ESRI_Geology.gdb" in your project folder (Fig. 1 a. Take same geologic contact, and identify another (different) topographic contour line that crosses at two points, draw a line between them (1) You now have two strike lines on the same geologic bed (2) draw a line perpendicular to . 1 with either strike or dip. Figure 12.20 A depiction of an anticline and a dyke in cross-section (looking from the side) and in map view (a.k.a. The areas underlain by each unit are indicated on geologic maps by polygonal areas with distinctive fill colors and patterns. Some geologic maps have multiple cross-sections, and will include all of these on a separate page or on an expanded map sheet. 4. Finally add some code to draw a line from the coordinates for the dip lines. The contours are there too, in brown, plus the symbols for various water features in blue. If the plane is flat there is an infinite number of strike lines, all having the same dip (zero) but different bearings. You can see the basic things discussed earlierthe shorelines, roads, towns, buildings and bordersin gray. building a geologic map from scratch, and so many steps involving geodatabase construction and . This is easiest where a contact is steep. A geologic cross-section will be labeled on the map itself with a bold line and letters marking either end of the cross-section, usually with A-A', B-B', etc. Use the azimuth protractor in the back of the manual to draw the indicated strike lines on each compass. Geologic maps that display strike and dip symbols require the label to be rotated with the symbol. plan view) with the appropriate strike-dip and anticline symbols. Calculating Dip By definition, dip is perpendicular to strike, and by using the Rule of V's (Figure 7) you can determine the direction of dip. Use strike lines to calculate dips of faults or beds when not indicated by strike and dip measurements on the map. The dip gives the steepest angle of descent of a tilted bed or feature relative to a horizontal plane, and is given by the number (0-90) as well as a letter (N,S,E,W) with rough direction in which the bed is dipping downwards. Making Geologic Maps Map Units In making a geologic map, the geologist must recognize or define units or rock or surficial sediment that can be differentiated and mapped. Prediction and interpretation is done to an area and field observations is to prove the results of the . This strike can then be measured on the map using a protractor. Find the closest longitude line to your strike line. ArcCatalog layout, showing blank mapping geodatabase downloaded in Section 1.2 above. Two Strike lines from contours of different values are drawn for the same boundary. To determine the strike, measure the angle between your constructed strike lines and the North direction on the map. 2 N 550 N 300 The beds on the east side are dipping to the east. Draw straight lines to link each photograph (A - G) with the locality (marked 1 - 15) on the map where you think it was taken. And a line having the same length is drawn on the drawing paper somewhere below the profile already made. a. Public Review Draft - Digital Cartographic Standard for Geologic Map Symbolization PostScript Implementati on (filename: of99-430_02-02.eps) REF NO DESCRIPTION SYMBOL CARTOGRAPHIC SPECIFICATIONS NOTES ON USAGE . This map, the Camp Davis Quadrangle, shows the geology at the southern end of Jackson Hole, a beautiful valley along the eastern edge of the Grand Teton Mountains. Figure 3. Here's a small sample of a real geologic map. Below is a simplified map of the geology around the fictional town of Rioville. On a geologic map, this is represented with a short straight line segment oriented parallel to the strike line. You see a strike and dip symbol on a geologic map. Form-lines help the geologist to visualize the structure at the scale of the landscape and help them to identify key area such as large scale fold hinges, unconformities etc. Turning on and off the topo view with the Google Earth grid lines clicked -on will allow determination of what lines are longitude lines. To measure the strike, draw a strike line where a topographic contour of your choice intersects your chosen lithologic contact. IV Appearance of planar beds on a geologic map A Planar beds have a constant strike and a constant dip B Strike lines along structure . Strike (4x4) Dip (4x4) 3b Draw four attitude symbols on the map that show the strike and dip of each feature (draw one for each feature). STRIKE: The direction of the line formed by the intersection of a horizontal plane with a bedding or fault plane. The two map views in Fig. Draw another strike line for the same bedding plane with consecutive contour to calculate the dip of the bed and direction.