1. A high school student poking around in the desert in 2009 found what has been determined to be the youngest and most complete specimen of a juvenile Parasauralophus ever discovered! See http://tinyurl.com/n4war6u for the news story, and http://dinosaurjoe.org/ to read more about the specimen and its importance. Geology in the news:

2. Very active - initially molten, then skinned over with a thin surface layer, continually broken by volcanic activity.

3. The ACASTA GNEISS is the oldest known intact rock on Earth – ca. 4 BILLION years old. Individual reworked zircons in NW Australia have been dated to 4.3 BILLION yrs.

4. (We had also lost most of our hydrogen and helium to space by this time….)

5. 5-70 km thick5-70 km thick - 40-70 km under continents, - 5-8 km under ocean basins continental & oceanic crust are intrinsically differentcontinental & oceanic crust are intrinsically different Continental crust esp. enriched in lighter elements (O, Si, Al, Na, K)Continental crust esp. enriched in lighter elements (O, Si, Al, Na, K) - relatively low in Fe, Mg, Ni - relatively low in Fe, Mg, Ni - density 2.7-3.0 grams/cm 3 - density 2.7-3.0 grams/cm 3 - highly complex & heterogeneous - 40-70 km thick Oceanic crust more like mantle beneath itOceanic crust more like mantle beneath it - lower in Si, Al, Na, K - higher in Ca, Fe, Mg - density 3.0-3.3 grams/cm 3 - 5-8 km thick The CRUST is that which we know best.

6. - 2900 km (1800 mi) thick - comparable to the distance from Maine to Colorado - depleted of light elements (Al, K, Na) - believed to be mainly Fe, Mg silicates (top) and Fe, Mg oxides (at base) - density 3.5 grams/cm 3 (top) to 5.5 grams/cm 3 (bottom) - source for most magmas (molten rock) The MANTLE is beneath the crust

7. The CORE is composed mostly of iron (Fe) with some nickel (Ni) Inner Core - 2200 km thick (1300 mi) - molten - flow generates magnetic field (how?) - density 10-12 grams/cm 3 - 1200 km radius (750 mi) - probably solid - density 12-13 grams/cm 3 (2x density of iron at surface; = Pb) Outer Core

8. NO ONE HAS ACTUALLY SEEN THE MANTLE OR THE CORE What we believe about them is based on: 1. Meteorites & Lunar specimens

9. One of hundreds of lunar specimens returned by Apollo mission astronauts.

11. The Asteroid Belt was at one time thought to be a planet that was destroyed by a great impact. It's now considered that the total mass here is insufficient to draw together into a single planet, with Jupiter's gravitational pull continually disrupting processes that would lead to clustering.

13. ophiolites 3. rare rocks (fragments of uppermost mantle) exposed in mountains where upper parts of the oceanic crust and mantle are folded, buckled & pushed up ( called ophiolites). Peridotite

14. At this site in Newfoundland, the pillow lavas are shown in contact with the underlying mafic plutonic rocks of the oceanic crust.

16. One proposed model for emplacement of ophiolites:

17. seismic waves 4. behavior of seismic waves from earthquakes & large explosions (e.g., nuclear tests) 5. theoretical studies

18. For MOST of the semester, we're going to be focusing on the part we know the best - the crust. (Be it ever so humble, there's no place like home!) (at least in part!!)

19. "Hadean" (Ediacaran)

22. Modern Archaea don't look all that different.

25. Australia Hibbing Mine, Minnesota Banded Iron Formations (BIF) are also characteristic of Archaean terranes.

27. Archean Rocks in North America Archean rocks are the oldest in the SHIELDS, the stable cores of continents They are comprised almost entirely of metamorphic rocks.