There are two different methods for generating a hierarchy, the Layer Thickness method and the Strike/Dip method. We will demonstrate both as we go through the workbook.
The Layer Thickness method uses the Distance slider to move the surface up or down the borings within the selected material. The bottom elevation of each layer at every boring is specified by adjusting the distance slider within the maximum value which corresponds to the maximum thickness for the slected material at any boring.
The strike and dip values are used to define creates two visualization planes, a Top surface and a lower second parallel surface whose position is defined by the Tolerance slider. The upper surface is automatically positioned at a the highest possible (locked or automatically selected) sphere. No other point defining the surface we are working on can be above the Top surface. The lower plane is twice the tolerance below the top plane.
By increasing your tolerance value, you allow the bottom of your layer to vary more, which will create a "thicker" layer overall. Shrinking your tolerance value will force the layer to more closely follow your strike and dip, but may result in creating extra layers.
The difference between the two is highlighted when using the cycle option. The cycle option will try to automatically create your hierarchy for you. If the Layer Thickness method has been chosen, the cycle option will set the distance to the max distance and write out the bottom of the layer, it will do this repeatedly until it all borings have been dropped from the surface. This works very well if you have very simple, "pancake-style" lithology. If there was a strike or dip to the layers and if any layers are pinching out at the ground surface, the geology would not be properly created with this method. The Strike/Dip Method can be used to automatically generate models to avoid these problems, but requires more setup and user guidance. Since this method is based on a strike and dip these will be honored even when cycling. The difficult aspect of this automated method is choosing the correct tolerance.
We will begin by choosing the Layer Thickness method.
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