Friday November 11, 2011

1. FridayNovember 11, 2011 (?? )

2. The Launch Pad Friday, 11/11/11 List the major steps in the development of Earth’s atmosphere and oceans that lead to life on Earth as we know it today. Earth’s primitive atmosphere was formed by a process called “outgassing.” Water vapor condensed to form clouds and rainwater that formed the oceans. • Oxygen levels in the atmosphere steadily increased as a result of photosynthetic bacteria in the ocean. Outgassing produced acidic conditions that caused an accelerated rate of weathering of Earth’s rocky surface. • Products of this weathering were carried to the oceans, thus increasing the salinity of the oceans..

3. The Launch Pad Friday, 11/11/11 How old is the Universe? 13.6 billion years old How old is the Earth? 4.5 billion years old

5. Announcements I will be available today after school until 5:00 PM.

6. Latest News In 2006, a farmer found a meteorite buried in a hillside in the Missouri town of Conception Junction (population 202). Only now has the out-of-this-world value of the space rock discovery come to light. Geochemist Randy Korotev of Washington University in St. Louis and his colleagues have identified the space rock as a rare type of pallasite meteorite worth about $3.4 million, the researchers said today. Only 19 other pallasites had ever been found in the United States. The meteorite traveled a long road to find its way into Korotev's hands. Researchers think this meteorite was once part of an asteroid that orbited the sun in the asteroid belt between Mars and Jupiter. At some point, this fragment was knocked into an orbit that crossed Earth's path, and it was pulled down to our planet by gravity.

7. The Geologic Time Scale

8. The Geologic Time Scale • The geologic time scale divides geologic history into units. • Subdivisions of the scale: • Eon - greatest expanse of time. There are four eons • Phanerozoic (“visible life”) – the most recent eon • Proterozoic • Archean • Hadean – the oldest eon • Era - Subdivision of an eon. Example: Eras of the Phanerozoic eon • Cenozoic (“recent life”) • Mesozoic (“middle life”) • Paleozoic (“ancient life”) • Eras are subdivided into periods. • Periods are subdivided into epochs.

9. The Geologic Time Scale • Eon • Era • Period • Epoch

10. The Geologic Time Scale

11. Figure 11.19 The Geologic Time Scale

13. Activity Make your own Geologic Time Scale, labeling all eons, eras, and periods. Include the epochs at your discretion.

14. The Launch Pad Wednesday, 10/20/10 In what eon, era, period, and epoch are we now living? The Phanerozoic Eon The Cenozoic Era The Quaternary Period The Holocene Epoch

15. Lab The Geologic Time Scale

17. The Launch Pad Thursday, 10/21/10 What are the names of the eons if we consider there to have been only two in Earth’s history? The Precambrian Eon and the Phanerozoic Eon If the Earth is 4 500 millions years old, how many years did each eon occupy? Precambrian – 3958 million years, Phanerozoic – 542 million years What percentage of Earth’s history did each occupy? Precambrian – 88%, Phanerozoic – 12%

18. Lab The Geologic Time Scale

20. The Launch Pad Friday, 10/22/10 Name an important factor that caused the Precambrian Eon to change to the Phanerozoic Eon. First organisms with shells and other hard body parts Name an important factor that caused the Paleozoic Era to change to the Mesozoic Era. Great Permian extinction Name an important factor that caused the Mesozoic Era to change to the Cenozoic Era. Extinction of dinosaurs and many other species

22. The Geologic Time Scale Geologic time is divided into Eons. • Precambrian Eon • Archean Eon • Proterozoic Eon • Phanerozoic Eon

23. The Geologic Time Scale Eons are further divided into Eras. • Archean Eon • Eoarchean Era • Paleoarchean Era • Mesoarchean Era • Neoarchean Era • Proterozoic Eon • Paleoproterozoic Era • Mesoproterozoic Era • Neoproterozoic Era • Phanerozoic Eon • Paleozoic Era • Mesozoic Era • Cenozoic Era

24. The Geologic Time Scale The Phanerozoic Eon is further divided into Periods. • Phanerozoic Eon • Paleozoic Era • Cambrian Period • Ordovician Period • Silurian Period • Devonian Period • Carboniferous Mississippian Period • Carboniferous Pennsylvanian Period • Permian Period • Mesozoic Era • Triassic Period • Jurassic Period • Cretaceous Period • Cenozoic Era • Tertiary Period • Quaternary Period

25. The Geologic Time Scale The Cenozoic Era is further divided into Epochs. • Cenozoic Era • Tertiary Period • Paleocene Epoch • Eocene Epoch • Oligocene Epoch • Miocene Epoch • Pliocene Epoch • Quaternary Period • Pleistocene Epoch • Holocene Epoch

26. The Precambrian Eon The Precambrian Eon, which is divided into the Archean and the Proterozoic Eons, spans about 88% of Earth’s history. Much of Earth’s stable continental crust was created during this time. Partial melting of the mantle formed volcanic island arcs and ocean plateaus.

27. The Precambrian Eon These crustal fragments collided and accreted to form larger crustal provinces. Larger crustal areas were assembled into larger blocks called cratons. Cratons form the core of modern continents.

28. Formation of Continental Crust According to one model, the growth of large continental masses were accomplished through the collision and accretion of various types of terrains, including volcanic arcs and oceanic plateaus.

29. The Extent of Crustal Materials Remaining From the Archean and Proterozoic Eons

30. Map showing the major geological provinces of North America and their ages in billions of years (Ga). It appears that North America was assembled from crustal blocks that were joined by processes very similar to modern plate tectonics. These ancient collisions produced mountainous belts that include remnant island arcs trapped by colliding continental fragments.

31. The Precambrian Eon The Supercontinents The supercontinents were large landmasses that consisted of all, or nearly all, of the existing continents. Pangaea was the most recent supercontinent, but perhaps an even larger one, Rodinia, preceded it. Splitting and reassembling of supercontinents have generated most of Earth’s major mountain belts. Supercontinents have also profoundly affected Earth’s climate over time.

32. Possible configuration of the supercontinent Rodinia Figure 12.15

33. The Precambrian Eon It was during the Precambrian Eon that life first began on the Earth. Although the Precambrian Eon contains some 88% of Earth's history, its fossil record is poor because organism were soft-bodied during this time, resulting in little remaining evidence.

34. The Precambrian Eon The majority of Precambrian fossils are stromatolites that are often heavily metamorphosed or deeply buried. However, preserved cells have been discovered at selective sites, such as the 2.0 Ba Gunflint Formation Jasper stromatolites from Gunflint Formation near Mackies, northern Ontario.

35. The Precambrian Eon The earliest life forms were prokaryotes that evolved in the seas, possibly as early as 3.8 Ga. • The first primitive prokaryotic single-celled organisms appeared in the oceans in the form of bacteria (eubacteria or Achaea).

36. The Precambrian Eon Earth’s first living organisms were probably chemotrophs existing in an anoxic world and producing H2S or CO2.

37. The Precambrian Eon Nearly 3.5 Ga, photosynthezing cyanobacteria began releasing oxygen into the atmosphere as a by-product of the process of photosynthesis.

38. The Precambrian Eon The first multi-cellular organisms appeared toward the end of the Precambrian Eon, sometime prior to 542 Ma.

39. The Precambrian Eon When the eukaryotes (single-celled organisms with a nucleus) evolved through endosymbiosis is disputed, with claims as early as 3.4 Ga, but with less equivocal fossils dating from 1.8 to .8 Ga.

40. The Precambrian Eon With the eukaryotes comes sexual reproduction, enabling genetic diversity and the concomitant ability to adapt to and survive environmental changes.

41. The Launch Pad Monday, 10/25/10 Describe the process by which continents were formed in the Precambrian Eon. Volcanic island arcs and oceanic plateaus rose up in the ancient seas due to the upwelling of magma from the upper mantle. The action of plate tectonics caused the arcs to accrete into crustal provinces. The crustal provinces then accreted into cratons. The cratons then accreted to form the foundations of the modern continents.

43. Activity • Get your tape from the Lab on the Geologic Time Scale. • On the front side (from Part 1), divide the Precambrian Eon into Eras. • Research what caused the Eras to change and note this on the tape. • On the back side (from Part 2), if you have not done so already, divide the Phanerozoic Eon into eras, periods, and epochs. • Research what caused the all of the changes and note this on the tape.