1. Interpreting Earth’s Rocks to Determine Its Past History

2. Geologic Time chapter 18 Relative Dating - sequence of geologic events in a region (order of past events) Not quantitative

3. http://www.angelfire.com/az3/mohgameil/Layering4.jpg Law of Superposition Oldest layer on bottom (if undisturbed) Only works for SED rocks Younger Older

4. Law of Superposition In horizontal rock layers, the oldest and first formed is on the bottom. 5 is the youngest because it is on the top, closest to the surface.

5. http://www.calstatela.edu/faculty/acolvil/sediment/superposition.jpg The Grand Canyon

6. Principle of Original Horizontality Sediments are originally deposited as horizontal (or near horizontal) beds (ONLY FOR SED ROCKS) Folding happened AFTER rocks were deposited

7. folded rock layers = compression by tectonic activity

8. Cross-Cutting Relationships (overlap law) An igneous intrusion (or fault) is younger than the rock layers that it cuts across. fault oldest These are younger than the surrounding rock youngest

9. Cross-Cutting Relationships 6 is younger than1, 2, or 3 because it cuts across them!

10. 1 1 2 2 3 3 4 5

11. Which came first? A C B D E Order the rock layers above from oldest to youngest.

12. Which came first? The first layer deposited and the oldest is D, followed by C, A, B, and E. D D D C C A B B E

13. Law of inclusions The inclusion (xenolith) is older than the rock it is in Snickers bar

14. James Hutton: The father geology (1726-1797) Uniformitarianism: processes acting on earth today (volcanism, erosion, plate tectonics, glaciation, etc.) have done so in the past IN THE SAME WAY! “The present is the key to the past.”

15. Unconformities = “Missing Time” Represented by squiggly lines on cross sections

16. Angular unconformity

17. Angular Unconformities Folded layers below horizontal layers. angular unconformity ( rock layers have been eroded away) rock layers are eroded new horizontal layers are deposited

18. FEDCBA Angular Unconformity sedimentary rocks above and below unconformity surface with rocks below tilted at an angle

19. Granite sedimentary rock layers Cambrian Precambrian Nonconformity – younger sedimentary rocks rest on older igneous rocks

20. Nonconformity

22. Disconformity DISCONFORMITY:Missing rock layers (sedimentary) Very hard to pick out

23. Disconformities

24. Let’s Play…. Name the UNCONFORMITY!

25. Siccar Point, Scotland

28. http://www001.upp.so-net.ne.jp/fl-fg/06-02.htm

31. Resources http://courses.geo.ucalgary.ca/glgy209L03/docs/Lecture15_GLGY209_six.pdf http://perth.uwlax.edu/faculty/stoelting/Intro/Guides/Images2/law_of_superposition_b.jpg http://www.science.sjsu.edu/scied/255/ppt/superposition/img025.jpg http://www.gpc.peachnet.edu/~jsummero/Cross-cutting-a.jpg http://www.gc.maricopa.edu/appliedscience/gjc-nsf/images/CRH0204.JPG http://maverick.gc.maricopa.edu/appliedscience/gjcweb/geomap/images/ang.unconf.jpg http://www.geog.ouc.bc.ca/physgeog/contents/images/hutton.jpg http://www.bigbendpaleo.com/Photo%20Gallery/Big%20Bend%20Region,%20Texas/Big% 20Bend%20National%20Park%20-%20Syncline%20-%20Javalina%20Creek%20- %2020%20June%201995.jpghttp://www.bigbendpaleo.com/Photo%20Gallery/Big%20Bend%20Region,%20Texas/Big% 20Bend%20National%20Park%20-%20Syncline%20-%20Javalina%20Creek%20- %2020%20June%201995.jpg http://geoimages.berkeley.edu/GeoImages/Johnson/Images/Large/CD3/028.jpg http://www.vvdailypress.com/travel/rainbow/images/rock.jpg http://academic.emporia.edu/aberjame/struc_geo/folds/fold06.jpg http://www.geology.pitt.edu/images/folds.jpg http://faculty.evansville.edu/de3/b39902/PPoint/Geologic%20Time/img007.jpg http://www.photo.net/photo/pcd2882/grand-canyon-region-aerial-85.3.jpg http://www.cowanstark.com/horsehoe-bend.jpg http://home.flash.net/~alanm52/Cross_cutting.jpg http://www- class.unl.edu/geol101i/images/igneous%20images/Black%20Canyon%20Gunnison.jpghttp://www- class.unl.edu/geol101i/images/igneous%20images/Black%20Canyon%20Gunnison.jpg http://freespace.virgin.net/craven.pendle/stratigraphy/unconformity.jpg

32. http://comp.uark.edu/~sboss/siccar.jpg http://www.pittstate.edu/services/scied/Teachers/Field/Camp/Us67-1/us67cut.jpg http://maverick.gc.maricopa.edu/appliedscience/gjcweb/geomap/images/MW8-11.jpg http://www3.uakron.edu/geology/Foos/parks/rmgcan2.html http://www.ldeo.columbia.edu/edu/dees/ees/ies2/slides/disconformity.gif http://geology.lssu.edu/NS102/images/figure%2009-06.gif http://www.crienterprises.com/C-Assets/J-Hanifa-Unconf-W-Birk.jpg http://www.uoguelph.ca/~sadura/stgref/stg32b.gif http://www.geo-outdoors.info/images/eye_protection.jpg http://enterprise.cc.uakron.edu/geology/natscigeo/Lectures/time/gtime1.htm