This geologic history sign is one of six interpretive signs at the south Silver Point VP.
Marker Name: A Land of Fire and Water
Marker Text: The jagged sea stacks and towering rocks along the Oregon coast are carved from the mainland by powerful storm waves. But what causes the waves to wear away some areas and leave others to stand sentinel behind? The answer lies in geologic history.
17 million years ago - This region was underwater. Over the course of the next five million years, a series of enormous basalt lava flows issued from vents near the Idaho border and flowed down the ancestral Columbia River to the ocean.
12 to 15 million years ago - Plunging into the soft marine sediments, the molten basalt spread out in layers many miles underground and re-erupted through the seafloor as secondary submarine volcanoes.
Around 10 million years ago - The molten rock had solidified within volcanic conduits to form cylindrical intrusions; sometimes it cooled to form sheet-like dikes and sills, or irregularly shaped bulbous masses. Uplift and erosion began.
10 million years ago to present - The seafloor uplifted by several thousand feet and became the mountains of the Coast Range. As the ocean pounded at the shores, it eroded away the softer marine sediments leaving the harder basalt behind to form headlands and sea stacks.
Visit Instructions:
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