Generalizations


GENERALIZATIONS: The youngest rocks occur in the center of a(n) (anticline and dome, syncline and basin). The oldest rocks occur in the center of a(n) (anticline and dome, syncline and basin). The dip is always toward the (younger, older) rocks.

illustration
If two layers of rock are the same thickness, such as the sandstone in figures 8 and 9, but one dips steeper than the other, the one with the steepest dip will be represented on the surface by (narrow, wider) outcrops.

Another useful feature on geologic maps are geologic V's. When a stream crosses a contact, USUALLY the contact will be shown as a V pointing in the direction of the dip on the geologic map. This is because the stream has cut down and is actually flowing on older rock than beside it in the valley. The stream has cut through the younger rock and has exposed the older rock. The contact or boundary between the two rocks or the contact then has to bend in the direction of the dip. The direction the stream flows does NOT matter!

geologic V's

On figure 10, the strike symbols are (green,blue). The correct dip symbols are (light purple, orange, yellow, red).


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