Intrusive Contacts

A.  Pegmatite intruding gneiss, Death Valley, CA.

B.  Granite intruding gneiss, Rocky Mountain National Park, Colorado.

* May show small-scale intrusions (apophyses) into country rock. Photo A, above. Click here for another example.

* May show inclusions of country rock.

* Intruding rock may display chilled margins.

* Country rock may display hornfels texture or have otherwise "baked" appearance.

* Zone may show high degree of hydrothermal alteration.

To see a variety of intrusive contacts, click here.

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