11/28/2023 0 Comments Strike definition geology![]() ![]() However, it seems for now these automated systems cannot surpass the ability of a skilled Geologist. In order to get accurate measurements, some companies use surveying computers and GPS systems to collect field data. You may use other methods right hand or right arm. ![]() These are general rules I used when taking measurements of outcrops. It is important that the direction which strike angle is measured depends on the direction of the dip. Measure the angle between the North direction and the strike direction. Place your navigational protractor with the North of the protractor pointing to the North direction of the map.Ĥ. Extend your thumb and the thumb is now pointing towards the strike direction.ģ. Place your right hand with your four fingers pointing in the direction of the dip mark (tick line perpendicular to strike).Ģ. If the geological map contains structural features with strikes and dips, the strike lines should be drawn with the correct azimuthal angle, then:ġ. This map only has contour lines with no strike/dip data. This is explained in detailed in How to Read a Geologic Map. The dip can be calculated using the contour interval and the lateral distance between them. Place a navigational protector and measure the angle from the North towards the direction of the strike.ĥ. Your thumb is pointing towards the strike direction.Ĥ. Place your right hand on the map and rotate your hand until your four fingers are pointing towards the lower contour values.ģ. The dip direction follows from higher contour interval to lower contour interval.Ģ. If the geological map only has contour lines, but no strike and dip information are given:ġ. Now you are facing in the strike direction while your right arm is in the dip direction. Adjust your position until your shoulders are perpendicular to the feature. Turn until your right hand side of the body is in the direction of the dipping plane.ģ. Stand on the side or on top of the dipping surfaceĢ. However, when taking precise measurements, you may still use the right hand itself.ġ. This technique can be used on large scale features to obtain the general direction of the strike and dip. Arrows are drawn to indicate the actual straight direction. Note that the thumb doesn’t have to perfectly align in the strike direction. The direction which your thumb is pointing to is the direction of the strike. Finally, extend your thumb on the same plane. Rotate your hand so that the four fingers points down towards the dip direction.ģ. Place your right hand on the surface (if the feature you are interested in is visible).Ģ. Both accomplish the same task, but using the arm is best suitable for large scale features on an outcrop.ġ. The right hand rule using right arm and the right hand rule using the right hand itself. ![]() Furthermore, you should also take into account the wreathing, tectonic events and other natural phenomena. Large boulders in the field may appear as outcrop, but their strikes and dips are nonsensical. To obtained precise measurements, you must find an exposed outcrop. Once you obtained the general direction of the strike and dip using the right hand rule, you should always measure the maximum dip angle, prior to obtaining the strike. It is important that the dip is taken in the direction of maximum slope angle. The strike is drawn with respect to North or azimuthal angle φ. On a map or a cross section, dip is usually indicated by a short line perpendicular to the strike in the direction. Another is to use the convention Strike/Dip, where Strike is represented by three numbers, while dip is represented by two (SSS/DD). One is using a line drawn according the angle of the strike. The data is recorded on field books in two different ways. Based on the dip direction, one can obtain the direction of the strike. In other word, dip is a measurement of the gradient of the geological feature.Īccording to the Right Hand Rule (RHR), the strike direction depends on the dip. Dip is the angle of the “slope” to the plane. Geologists use strike, which is an imaginary horizontal line on a plane measured from the North. But with the force of gravity and other external forces, different layers may dip in any direction. Beds and rocks are usually deposit horizontally (more or less) in nature. Measuring Strike and Dip of an Anticline.Field Geology is a three dimensional science involving spatial orientation of points and plains. It is not a universal rule hence the term “right hand rule” is a misnomer. The right hand rule is an arbitrary standardization used by some Geologists. These data later can be used for analysis and interpretation. Field Geologists record strike and dip of structural features. In Structural Geology, the orientations of geological features are extremely important.
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