Depositional Contacts

A.  Depositional contact of sandstone over conglomerate.

B.  Depositional contact of conglomerate over tuff.

* No visible faulting--instead the overlying rock appears "glued" to the underlying rock.  Photo A above.

* May show erosion or scouring along the base.  Photo B above.

* May contain clasts of the underlying rock.  Photo B above.

* May have a conglomerate immediately overlying the contact.  Photo B above.

* May truncate structures in underlying rock. Click here for example.
unless it's a buttress unconformity, bedding above depositional contacts always lies parallel to the contact.

* May or may not show development of soils at contact.

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