Friday Field Foto #9: Igneous intrusion cutting across folded strata

This week…another photo from Chile.

Cretaceous Tres Pasos Formation cross cut by Miocene intrusions (©2009 clasticdetritus.com)

Here we got a good ol’ geologic puzzle…the kind you’d learn in an intro class. Here we can use the intuitive law of cross-cutting relationships to determine the relative timing of events. First the sediments were deposited, then the lithified sediments (rocks) were uplifted and folded, then an igneous intrusion cuts across the fold. Finally, erosion reveals it all for us to see.

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