Yachats Basalt (Upper Eocene, ~36-37 Ma; Devil's Churn, Oregon, USA) 3 : 無料・フリー素材/写真
Yachats Basalt (Upper Eocene, ~36-37 Ma; Devil's Churn, Oregon, USA) 3 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Basalt in the Tertiary of Oregon, USA.This is Devil's Churn in far-western Oregon. The site is usually incorrectly spelled "Devils Churn". The bedrock in the area is the Yachats Basalt, a Late Eocene unit consisting of basaltic lava flows and agglomerates, plus some andesite and trachyandesite. Igneous dikes are also present - most are basalt, plus minor andesite and rhyodacite. The basalt lava flows are often porphyritic, with labradorite plagioclase feldspar phenocrysts. Glomeroporphyritic varieties are present, with clusters of blade-shaped plagioclase phenocrysts.The linear valley at Devil's Churn is a fault zone that has been erosively enlarged by wave action from the Pacific Ocean. Landward, the chasm ends at a sea cave, which suggests that the entire feature was formerly a sea cave, but most of the roof has collapsed.-----------------------------------From park signage:The Power of Devils ChurnPulverizing and pounding.Crashing and smashing.Endlessly, relentlessly, the Pacific Ocean careens into Devils Churn, until the crescendo of waves explodes in a riot of white froth . . . and then escapes back to the sea.Showtime!Devils Churn puts on its most dramatic shows during high tides and storms.Devils Churn began as a small fracture - a weak area in the ancient volcanic rock.Thunderous waves have gnawed at the rock for eons, eroding it away grain by grain, enlarging the crack into a chasm.As you approach, you'll feel the power of the churn like thunder in your bones, and anticipate each collision of wave and rock like bursting fireworks!The sea never finishes its work . . . All along the coast, you'll see chasms-in-the-making. Some are only tiny fissures today - reminders of the Devils Churn's modest beginning.If you venture closer, watch your footing on slippery rocks, and never turn your back on the ocean!-----------------------------------Stratigraphy: Yachats Basalt, Upper Eocene, ~36-37 MaLocality: Devil's Churn, south of Yachats, coastal Oregon, USA |
| 撮影日 | 2012-08-03 17:20:48 |
| 撮影者 | James St. John |
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