Sometimes, especially after field visits, we may be confident to infer the lithology or facies of vertical sections of the outcrop we are interpreting.
To add a new lithology log, right click on the node “lithology” and select “Add new…”. Rename the element as appropriate.
Icons will appear at the top of the screen.
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These control how the element is digitized as follows –
1. Add one ore more points. Simply click on any point on the outcrop, lines will join each point digitized. Click on the tick(6) icon to complete the boundary or hit Escape on the keyboard. OpenOutcrop has been designed so that clicking in the middle of two existing points will insert a new one between the two. Points should be digitized from top to bottom in (roughly) a straight line. Any log created will in true vertical depth. Try and digitize points at facies boundaries.
2. Move one or more points. Simply click and drag.
3. Delete one or more points. Click close to any point to delete it.
4. Undo (the previous operation).
5. Redo (the previous operation).
6. OK, I’m finished with the current operation.
Once you have digitized the element (or while you are digitizing), it will be displayed as in the following –
Note that an empty log appears on the right hand side with the intervals marked as per the points digitized. To set the lithology of an interval, simply click anywhere in the log between two points.
You can set the modal grain size for each interpreted interval by simply dragging it to the left or right as appropriate. Note the scale at the top of the log, each division is classed (on a Wentworth scale) as
· Very coarse sand
· Coarse sand
· Medium sand
· Fine Sand
· Very fine sand
· Coarse silt
· Medium Silt
· Fine sile
· Very fine silt
Each of these can be translated into ranges of grain size (on a logarithmic scale). When exporting data, the inferred (numeric) grain size is also exported.