S. Farooq  
Department of Geology
Aligarh Muslim University
 

email farooq.amu@gmail.com

Virtual Geological Field Trip to Jhalawar

 

Determining Strike and Dip in Google Earth

In rugged areas where there is substantial outcrop (mountains, deserts) it is possible to determine the area’s structural character (strikes, dips, folds) using GIS software, including Google Earth.

To draw a pair of strike lines:

  1. Locate a distinct planar feature such as a lithological contact
  2. Mouse over the feature noting the elevation values at the bottom of the window. Note the range of elevation over which the surface outcrops (maximum and minimum elevations)
  3. Pick an upper contour value near the maximum elevation.
  4. Click on the Add Path icon at the top of the screen (or select Path from the Add Menu)
  5. Enter the structure contour name in the Pop-Up window (e.g., 550 m Structure Contour)
  6. Move the cursor along the contact until the elevation corresponds to the desired elevation for your upper contour (e.g., 550 m). Left click to mark the point.
  7. Click OK on the bottom of the New Path pop-up window.
  8. Move the cursor along the contact until you find a second point at which the elevation corresponds to the desired elevation for your upper contour (e.g., 550 m). Left click to mark the point, and define the structure contour. (Note that if you would like to correct either of the points that you selected, you can left click on the end point and pull it to a new location.)
  9. Pick a lower contour value near the minimum elevation.
  10. Click on the Add Path icon at the top of the screen (or select Path from the Add Menu)
  11. Enter the structure contour name in the Pop-Up window (e.g., 500 m Structure Contour)
  12. Move the cursor along the contact until the elevation corresponds to the desired elevation for your lower contour (e.g., 500 m). Left click to mark the point.
  13. Move the cursor along the contact until you find a second point at which the elevation corresponds to the desired elevation for your lower contour (e.g., 500 m). Left click to mark the point, and define the structure contour.
  14. Click OK on the bottom of the New Path pop-up window.

To determine strike direction:

  1. Determine the dip direction (direction in which structure contours decrease in elevation), and use the right-hand-rule to determine which end of the structure contour to measure
  2. Click on the north arrow in the top right corner of the screen to confirm that the screen view is aligned with north-to-the-top
  3. Under the View Menu, select Grid
  4. Use your protractor to measure the strike direction after aligning the protractor’s grid with that of the Google Earth screen

To determine the dip angle:

  1. Zoom in on your pair of structure contours, and center them on your screen
  2. Click on the Ruler icon at the top of the screen (or select Ruler from the Tools Menu)
  3. Center the crosshairs on one structure contour and left click
  4. Use the mouse to drag a line toward the second structure contour. When this new line is perpendicular to your structure contours, and the crosshairs are centered on the second contour, then left click with the mouse. (Note that if you would like to correct either of the points that you selected, you can left click on the end point and pull it to a new location.)
  5. In the select feet as the unit in the Ruler Pop-Up window and record the value.
  6. Use this horizontal distance, and the structure contour interval to calculate the dip angle using trigonometry.

Use the method described above to determine the strikes and dips of beds at the following locations:

Location

Latitude

Longitude

Strike

Dip

Iran

27.405900

53.355833

 

 

Iran

27.871297

67.182324

 

 

Algeria

32.995419

0.499526

 

 

Algeria

32.640238

-0.847844

 

 

Utah

39.525834

-113.813675

 

 

What can Google Earth do?

View a low resolution geological map of Jhalawar area in Google Earth

In the area around Jhalawar, note the relationship of geology with:

  1. Cultivated and uncultivated areas
  2. Human settlements
  3. Density of forest cover
  4. Lineaments
  5. Drainage patterns
  6. Natural and man-made lakes

Try and decipher geological, structural and lithological details on the basis of these.

General Information about Jhalawar
Places of tourist interest in and around Jhalawar

   


This website is hosted by

S. Farooq

Department of Geology

Aligarh Muslim University, Aligarh - 202 002 (India)

Phone: 91-571-2721150

email: farooq.amu@gmail.com