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32. Flood basalts Dan Barker April 2009 Creag Mhor, Isle of Mull, Scotland.

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Presentation on theme: "32. Flood basalts Dan Barker April 2009 Creag Mhor, Isle of Mull, Scotland."— Presentation transcript:

1 32. Flood basalts Dan Barker April 2009 Creag Mhor, Isle of Mull, Scotland

2 About 55 million years ago, while the North Atlantic opened up, enormous outpourings of basalt lava covered western Scotland, Northern Ireland, and eastern Greenland. Creaga Ghaill, Mull.

3 Thick stacks of lava flows built up in a few million years. Most flood basalts erupt from long fissure systems, not from a central vent. Bearraich. Mull

4 Floddigarry, Isle of Skye

5 Struan, Isle of Skye

6 The same thing happened in NE Africa, starting about 40 million years ago. 89 km south of Asmara, Eritrea

7 The Simien Mountains, Ethiopia, are a spectacular remnant of these flood basalts.

8 Wrangellia Basalts, Vancouver Island, BC, formed 230 million years ago on an oceanic plateau in the SW Pacific, before colliding with North America.

9 Another view of the Wrangellia Basalts,Vancouver Island, BC

10 North America's youngest flood basalts cover about half of Washington State. Columbia River Basalts, Snake River.

11 Eruption of the Columbia River Basalts, WA, peaked about 16 million years ago, and 95% of the volume erupted in less than 1 million years.

12 Many Columbia River Basalt flows show prismatic joints, from interactions with surface water. Palouse River WA

13 There was enough time between flows for thick soils to develop. From Wishram Heights WA

14 The Dalles WA

15 Wanapum Basalt at the Dalles

16 Columbia River Basalts warped by an anticline, WA


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