The Ventura Red Beds are a lower part of the Midnight Peak Formation which contains shale and sandstone with lots of hematite. The reddish color of the oxidizing hematite, as reflected in the name of this group. These red beds contain red and green shale. The red indicates oxidation, while green reflects reduction. The brown patches within the shale originated as organic matter that does not allow redox reactions. Hematite is a paleoclimate indicator that was deposited in a hot climate that was tropical to subtropical. These red beds were deposited 88-90 million years ago (during the Wrangella collision), reflecting a time of global warming.
Ventura Red Beds