Geology Reference
In-Depth Information
A field of seastacks that make up Mack Reef south
of Crook Point are composed of rocks of the Otter
Point Formation (photo courtesy of E.M. Baldwin).
Groups of offshore stacks and submerged rocks
making up a coastal belt of Cretaceous and Jurassic
rocks from Gold Beach to Cape Blanco are part of an
extensive reef complex that includes the Rogue River,
Port Orford, and Cape Blanco reefs. Black Rock is the
southern most projection of the Orford reef, and the
larger Castle Rock above Cape Blanco is the northern
most point. Sea stacks here with imaginative names as
Arch Rock, Best Rock, Large Brown Rock, and Square
White Rock ate sandstones, volcanics, and conglomer-
ates of these two reef systems. The third line of rocks,
Rogue River reef offshore north of Gold Beach, is a
complex jumble of conglomerates and sediments that
project from the ocean as Pyramid Rock, Double Rock,
and Needle Rock.
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