1. Geology Field Guide of Jemez Mountains and Capulin Volcano By Dorey Smith

2. Stop 1 Dinosaur Quarry North West Oklahoma Exiting Great Plains –Surface Neogene –Upper Morison Formation (Upper Jurassic) –Mesozoic sands Cross bedded sandstone (current activity) Easter egg shale (pastel colors) Geology History –Zuni Sequence Coarsening upward Possible river system or flood plain Environment Terrestrial

3. Samples Sandstone current activity Shale

4. Samples Slip Slide Burrows

5. Stop 2 Clastic Dikes The remains of a volcanoes innards Volcanic plumbing system Remnant of volcanic cone after erosion Vent grow younger as you move east

6. Black Mesa Pliocene Basalt Flows Remnants of Lava flows after erosion and streams broadening their valleys result in isolated lava capped mesas

7. Stop 3 Chiflo Dasite volcanic cone surrounded by later flows from other cones Vent of flow is south of the cone Located on edge of Rio Grande Rift

8. Samples Basalt –Some olivine crystals in basalt

9. Stop 4 Chiflo

10. Stop 5 Valle Caldera in Jemez Mountains Caldera formed 1.2 Mya Ash released was approximately 300km 2 forming the Tshirege Member of the Upper Bandelier Tuff

11. Stop 5 Bandelier Tuff Pumas beds several meters thick from Valle eruption

12. Sample Pumas –Dark with obsidian fragments –Very viscous

13. Stop 6 Guaje pumice bed Pumas bed –Light in color without volcanic glass fragments –Less viscous

14. Stop 7 Basalt flow of the Cerro del Rio volcanic field Basalt flow partially altered (yellowish brown in color) Guaje Pumice (1.62Mya) Otowi member Tshirege Member of the Bandelier Tuff

15. Samples Basalt flow where it meets the surface Basalt on top, surface sediments (at time of eruption) on bottom Root cast in sediment rock under basalt flow

16. Samples Bandelier Tuff Crystals in basalt resulting from slow cooling

17. Stop 8 White Rock Overlook Looking North towards Black Mesa Mafic flows overlie the Puye Formation and the Santa Fe sedimentary deposits

18. Stop 9 Capulin Volcano Cinder cone –Eruption from fissure vent 60,000 years ago –Molten rock few into the air and cooled falling to Earth in small rocks called cinder (frothy volcanic rock) and large chunks called volcanic bombs –Form cone shape around vent

19. Capulin First lava flow was to the east oozing through the cinder After the gas magma was depleted the explosive eruption ended The second lava flow was to the south Between the east and south lava flows there are wagon track from the Santa Fe trail

20. Capulin The third flow was to the southwest. The forth flow to the north east The lava flows cover about 16 square miles Ripple marks formed on the crust as lava continued to flow showing the direction of the flow movement

21. Capulin Center of cone in at a lesser elevation than the rim due to the formation of a cinder cone View of vent in the cone of volcano

22. Samples Cinder – frothy volcanic rock very viscous Basalt – with some viscosity due to slow cooling

23. Resources www.ees1.lanl.gov/roadgeology.html www.nps.gov/cavo/lava.htm