The layers of rock pictured here were seen today as we proceeded up Hells Canyon by jet boat. In this spectacular, deep canyon, these rather plain but rarely seen types of rock tell a fascinating story. The greenish gray layers formed on a mid-ocean spreading ridge. In the center of the Pacific ocean, hundreds of millions of years ago, a new tectonic plate formed as molten rock welled from hundreds of miles down. All of this happened under thousands of feet of sea water and deep within submarine volcanic vents, hardly a place where humans can observe the process of new ocean floor formation. But as that ocean plate was shoved beneath what was then the west coast, a bit of ocean floor was literally shaved off by the North American continent acting as a spatula. The subsequent cutting of Hells Canyon thousands of feet into the mountains of western Washington and eastern Idaho has provided us the opportunity to see just how the mighty Pacific Ocean plate was created.
- Daily Expedition Reports
- 27 Sep 2001
From the Sea Lion on the Columbia and Snake Rivers, 9/27/2001, National Geographic Sea Lion
- Aboard the National Geographic Sea Lion
- Pacific Northwest
The layers of rock pictured here were seen today as we proceeded up Hells Canyon by jet boat. In this spectacular, deep canyon, these rather plain but rarely seen types of rock tell a fascinating story. The greenish gray layers formed on a mid-ocean spreading ridge. In the center of the Pacific ocean, hundreds of millions of years ago, a new tectonic plate formed as molten rock welled from hundreds of miles down. All of this happened under thousands of feet of sea water and deep within submarine volcanic vents, hardly a place where humans can observe the process of new ocean floor formation. But as that ocean plate was shoved beneath what was then the west coast, a bit of ocean floor was literally shaved off by the North American continent acting as a spatula. The subsequent cutting of Hells Canyon thousands of feet into the mountains of western Washington and eastern Idaho has provided us the opportunity to see just how the mighty Pacific Ocean plate was created.
