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Minetosh online – Geology – Geo-1

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Help and info

Instructions, Troubleshooting, Version history, Disclaimer

This app should be self explaining and very easy to use. Nevertheless, some information concerning its use is given that might come in handy. What you can do with it will be explained below in the section dealing with geology.

Please use the dot "." as decimal point.

Choose what you want to calculate in the collapsible menu. The content of the page changes according to your selection. After clicking on the button "Calculate", the result will appear underneath. You may add a comment to your data.
You have the possibility to save your data including your comments locally in your browser. You may recall them any time. However, recalling the data only works on the device / browser on which the data has been saved. To do so, click on "Show / hide data". At the moment, no export-functionality is planned. But, data can be selected, copied and pasted as text into another program.

ATTENTION: Deleting data will erase ALL data!

Troubleshooting

Should you encounter strange results, or should the app behave otherwise strangely, the cause is often related to the browser cache. In this case, delete the browser cache or the recent history (often via the "History" menu), taking care not to delete important settings (cookies, etc.) as well. Reload the page. In rare cases it might be necessary to quit the browser and to delete the cache manually in the file system.

Version history

December 2018; Geo-1 v. 201812-1: First version

January 2019; Geo-1 v. 201901-1.1: Some corrections and improvements to the html-code

Disclaimer

THERE IS ABSOLUTELY NO GUARANTEE / WARRANTY CONCERNING THE ACCURACY AND PRECISION OF THE RESULTS!

The web-apps on the Minetosh online website are meant for information purposes only. The entire risk as to the quality, accuracy, precision and performance of these programs is with you! ALSO NO RESPONSIBILITY WHATSOEVER WILL BE ACCEPTED FOR ANY OTHER RISCS THAT GO BEYOND THIS. In particular, any damage or any other inconveniences (for example data loss) that may arise from the installation and / or use of these programs and the data produced by them (e.g. should the programs / results prove defective / erroneous)!

The same applies to all advices or instructions published on the Minetosh online website!



Outcrop 2

Kvikkjokk, Sweden: On the Sjnjierak: Micaschists


What you can do with Geo-1

An overview about the geological parameters Geo-1 can determine (for definitions see "Explanation of some geological terms").

Width of outcrop at an cross-section angle of 90°: Calculation of the width of outcrop for a given angle of β = 90° between the strike and the cross-section (cross-section angle).
Example: At a dip-angle of 45° and a thickness of 50 m, the width of outcrop is 70.7 m.

Thickness at an cross-section angle of 90°: Calculation of the thickness for a given angle of β = 90° between the strike and the cross-section (cross-section angle).
Example: At a dip-angle of 45° and a width of outcrop of 70.7 m, the thickness is 50 m.

Dip-angle at an cross-section angle of 90°: Calculation of the dip-angle for a given angle of β = 90° between the strike and the cross-section (cross-section angle).
Example: For a given thickness of 50 m and a width of outcrop of 70.7 m, the dip-angle is 45°.

Apparent thickness (cross-section angle independent): Calculation of the apparent thickness from values for dip-angle and true thickness.
Example: For a dip-angle of 50° and a true thickness of 60 m, the apparent thickness is 93.3 m.

True thickness (cross-section angle independent): Calculation of the true thickness from values for dip-angle and apparent thickness.
Example: For a dip-angle of 60° and an apparent thickness of 90 m, the true thickness is 45 m.

Dip-angle (cross-section angle independent): Calculation of the dip-angle from values for true thickness and apparent thickness.
Example: For an apparent thickness of 90 m an a true thickness of 45 m, the dip-angle is 60°.

True thickness (variable cross-section angle): Calculates the true thickness in a cross-section with a cross-section angle of β ≠ 90° from the values for the cross section angle β and the according width of outcrop and the dip-angle α. The cross section angle β may also be equal to 90°. Then, accordingly, you also need to enter the width of outcrop for a cross section at an angle of β = 90°.
Example: A layer has a dip of 45°. Based on a cross-section at an angle of β = 60° and an according width of outcrop of 65 m, a true thickness of approx. 40 m (39.8 m) can be calculated for this layer.
Limitations: Cross section angles of 0° and 180° don’t make sense and lead to erroneous results and are therefore not allowed. A dip value of 0° is also not allowed here.

Width of outcrop for a cross section angle of β = 90° (variable cross-section angle): For any given cross section angle and related width of outcrop you may calculate the width of outcrop for a perpendicular cross section.
Example: In a cross section with a cross section angle of 70° relative to the strike a layer shows a width of outcrop of 75.2 m (45° dip, 50 m thickness). Question: What is the width of outcrop in a perpendicular cross section? Answer: 70.7 m.
Limitations: Cross section angles of 0° and 180° don’t make sense and lead to erroneous results and are therefore not allowed.

Width of outcrop for a cross section angle of β ≠ 90° A (variable cross-section angle): From a given perpendicular cross section and its width of outcrop ("width of outcrop at β = 90°"), the width of outcrop for any different cross section angle is calculated.
Example: In a perpendicular cross section a layer’s width of outcrop is 50 m. At a cross section angle of 60° the layer’s width of outcrop would be approx. 58 m (57.7 m).
Limitations: Cross section angles of 0° and 180° don’t make sense and lead to erroneous results and are therefore not allowed.

Width of outcrop for a cross section angle of β ≠ 90° B (variable cross-section angle): Enter values for the cross section angle β, the true dip angle α and the true thickness and you get the width of outcrop as result.
Example: A layer has a dip of 45° and a thickness of 10 m. A perpendicular cross section shows a width of outcrop of 14 m. A cross section at 70° relative to the strike shows a width of outcrop of 15 m and a cross section at 45° relative to the strike shows a width of outcrop of 20 m.
Limitations: Cross section angles of 0° and 180° don’t make sense and lead to erroneous results and are therefore not allowed. A dip value of 0° is also not allowed here.

Dip angle α A (variable cross-section angle): Calculates the dip angle α as a function of the cross section angle β, the true thickness and the width of outcrop.
Example: A given thickness of 10 m in a perpendicular cross section with a related width of outcrop of 14 m (14.1 m) results in a dip angle of 45.2°. The same thickness in a cross section at 45° relative to the strike with a consequent width of outcrop of 20 m also shows a dip angle of 45° (minor differences are related to rounding errors).
Limitations: Cross section angles of 0° and 180° don’t make sense, lead to erroneous results and are therefore not allowed. Both the width of outcrop and the (true) thickness must greater than 0.

Dip angle α B (variable cross-section angle): Calculates the dip angle α as a function of the cross section angle β and the apparent dip γ.
Example: In a cross section with 45° relative to the strike, a layer shows an apparent dip of 15°. Entering these values shows that the true dip is about 21° (20.8°).
Limitations: Cross section angles of 0° and 180° don’t make sense, lead to erroneous results and are therefore not allowed. A dip value of 90° is also not allowed here.

Apparent dip angle γ (variable cross-section angle): The apparent dip γ is calculated as a function of the cross section angle β and the dip angle α.
Example: What value will a true dip of 40° show in a cross section at 45° relative to the strike? Answer: 36°.
Limitations: Cross section angles of 0° and 180° don’t make sense, lead to erroneous results and are therefore not allowed. A dip value of 90° is also not allowed.



Explanation of some geological terms

Some definitions

Figure 1 shows some geological parameters:

Definitions of geological terms

Fig.1: A schematic geological cross-section, showing the relation between dip, thickness, apparent thickness and width of outcrop.

Geological map and cross-section

Figure 2 shows a schematic geological map with strike and cross-section lines.

Geological map

Fig. 2: A schematic geological map with strike (green line), a cross-section line perpendicular to the strike (red line) and a cross-section line at an angle β different from 90° (blue line). The width of outcrop (wo) varies with the cross-section angle β (wo 2 > wo 1) and is smallest for β = 90°.

Figure 3 shows the schematic geological cross-section belonging to the geological map above.

Geological cross section

Fig. 3: Schematic geological cross-section. The interpretation of the geological map above shows the relation between map and cross-section.

Summary

Figure 4 shows a summary of the relations in map and cross-section

Summary

Fig. 4: A summary of the relations between strike (green lines), cross section angle β (I: β = 90°, red; II: β ≠ 90°, blue), width of outcrop, true dip α and apparent dip γ. The apparent dip γ is always smaller than the true dip α (γ < α). Also shown are the thickness m and the apparent thickness h. The later is a function of the dip angle α.





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