1. Columbia River Basalt Flows Icing the Cake

2. Volcanic Episodes 65 55 45 35 25 15 0 5 Age (Myrs) Western Cascade Arc (37-15 Myrs) Challis Arc (55-42 Myrs) High Cascade Arc (5-0 Myrs) Columbia River Basalts (17-6 Myrs, Most 17-14 Myrs) Yellowstone Hot Spot (14-0 Myrs)

3. Large Igneous Provinces (LIPs) Flood basaltAgeVolume (mi 3 (km 3 ) ) Siberian Traps250 Myrs950,000 (4,000,000) Deccan Traps66 Myrs475,000 (2,000,000) CRBs/Steens Mt.17-6 Myrs60,000 (250,000)

4. Columbia River Basalts (CRBs) F-1 Just the Facts: 1.17.5-6 Myrs old (mostly 16.5-14.5 Myrs) 2.Over 300 lava flows 3.Covers 63,200 mi 2 (164,000 km 2 ) 4.Volume = 41,600 mi 3 (171,000 km 3 )

5. CRB Landmarks Haystack Rock, Cannon BeachBeacon Rock, Columbia Gorge Multnomah Falls Dry Falls Palouse Falls

6. Relative Volume of the CRBs Columbia River Basalts (41,600 mi 2 ) Yellowstone Eruptions Tambora, 1815 Krakatoa, 1883 Mt. St. Helens, 1980 Crater Lake, 7,000 yrs ago Mt. Pinatubo, 1991

7. Basalt Thickness Thickness of Wanapum Formation

8. Divided into Four Main Formations (Based on chemistry, age, paleomagnetics) All Basalts

9. F-6 Age (Myr) FormationMember# of FLows Area (mi 2 ) Volume (mi 3 ) 6 Saddle Mountain Lower Monumental11704 8.5Ice Harbor483018 Buford12205 10.5Elephant Mtn25,190105 12Pamona18,710180 Esquatzel11,05017 Weissenfels Ridge44705 13Asotin12,49053 Wilber Creek21,19017 13.5Umatilla25,830170 TOTAL1911,800574 14.5 Wanapum Priest Rapids322,120670 Roza415,580310 15.3Frenchman Springs2126,9301,540 Eckler Mtn82,35041 TOTAL3637,0502,561 15.7-15.6 Grande Ronde 7 members (N)3344,1906,690 15.9-15.74 members (R)4545,45012,740 16-15.92 members (N)1539,5107,530 16.5-164 members (R)2737,3208,680 TOTAL12057,53035,640 17.5-17Imnaha? Members2619,3802,280 GRAND TOTAL31163,20041,588 6% 86% 7% 1%

10. Eruptions mostly finished by 14.5 Myrs

11. Imnaha Basalts (17.5-17 Mys) F-7

12. Grande Ronde Basalts (16.5-15.6 Mys) F-7

13. Wanapum Basalts (15.3-14.5 Mys) F-8

14. Roza Member Volume Roza Member (Wanapum Basalts) 1300 km 3 / 5-15 yrs Mauna Loa 1859 Eruption 0.27 km 3 / 10 months Laki (Iceland) 1783 Eruption 14.7 km 3 / 8 months Hawaii 1986-92 Eruption 0.5 km 3 / 6 yrs

15. One Flow in the Roza Member Volume: 700 km 3 Time: 7 days Velocity: 5-15 km/hr Fissure Length: >100 km Rate: 100 km 3 per day (1 km 3 per day per km of fissure) For Comparison - 1 Hawaiin Flow (0.001 km 3 per day per km of fissure)

16. Saddle Mountain Basalts (13-6 Mys) F-8

17. Other Flows - Part of CRB’s? Picture Gorge & Steens Mtn Basalts F-8 Steens Mtn (16.5-15 Myrs)

18. CRB “Feeder Dikes” F-7

19. Grande Ronde Feeder Dike Photo by Vic Camp

20. Over 300 Basalt Flows

21. Flow Anatomy Vesicular Top Upper Colonnade (not shown) Entablature Pillows (if it flowed into water) Main Colonnade

22. Flow Anatomy Vesicular Top Upper Colonnade (not shown) Entablature Pillows (if it flowed into water) Main Colonnade

23. Flow Anatomy Vesicular Top Upper Colonnade Entablature Main Colonnade (below pictue)