1. East African Rift
A triple junction joins the East African Rift System to the Gulf of Aden and the Red Sea
Oceanic crust began forming in the Gulf of Aden about 10 million years ago
Red Sea rifting began later and oceanic crust is now forming

2. East Africa Rifting Rifting in East Africa is in its early stages,
The continental crust has not yet stretched and thinned enough for new oceanic crust to form from below
Nevertheless, this area shows seismic activity and considerable volcanism
In the Red Sea, rifting and the Late Pliocene origin of oceanic crust followed vast eruptions of basalt

3. East African Rift
In East Africa, the continental crust has not yet stretched and thinned enough for oceanic crust to form from below
In the Middle East the movement of Arabian plate northward against Eurasia causes much tectonic activity

4. Orogenic Belts
Circum-Pacific orogenic belt and the Alpine- Himalayan orogenic belt are the sites of most recent geologic and orogenic activity

5. Alps
Folded rocks in the Alps of Switzerland

6. India Collides with Eurasia
The Indian plate moved northward for millions of years until it collided with the Eurasian plate

7. High pCO2 during early Eocene
Large-scale volcanism
Giant’s Causeway in N. Ireland
Early Tertiary age

8. What prompted Cenozoic climate decline and the onset of glaciation?
Main factors:
1. Continental drift Isolation of Antarctica and initiation of sub-Antarctic oceanic circulation; ice-sheet formation Isolation of Arctic Ocean; sea-ice formation
2. Orogenesis Isolation of continental interiors, particularly of Central Asia, as a result of uplift of the Himalayas and Tibetan Plateau. High altitude areas = more snow cover = high albedo = regional cooling.

9. Decreasing pCO2 after ~50 Ma
Collision began ~50 Ma
Increased weathering = Atm. CO2 decrease
CaSiO3 + CO2 =
CaCO3 + SiO2

10. Neogene Life
Isolation of Antarctica led to glaciation
Global cooling

11. The Ice Age Isthmus of Panama Emplaced 3.5–3 M years ago
Started modern circulation
Gulf stream carries salty Atlantic north
Cools, sinks
Oceanic conveyor belt

12. Cenozoic Life
Marine organisms survived mass extinction at the end of the Cretaceous
Populated oceans during Cenozoic Era
Forest (angiosperm) began to dominate land
Grasses appeared as climate cooled
Diversification of many new mammals resulted

13. Oligocene Epoch Climate continued to get drier and cooler
Favored growth of grasses and cone-bearing and hardwood trees
Earlier types of mammals became extinct
Larger species flourished
Deer, pigs, horses, camels, cats, & dogs
Link

14. Ice Age—Pleistocene Climate began to cool and new animals evolved
Mammoth
Saber-toothed cat
Modern Humans – Homo Sapiens

15. Baby Mammoth http://img.rian.ru/images/10412/88/104128804.jpg

16. Humans
First bipedal humanlike primates appeared about 6 million years ago during the Late Miocene
Earliest modern humans appeared about 195,000 years ago
Migration was influenced by Ice Age
Bering Strait was exposed and Humans likely walked across to North America

17. Pleistocene Epoch Several periods of glaciations
Animals had special characteristics that allowed them to endure the cold
Other animals moved to warmer regions
Less-adaptable species became extinct
Fossils of early ancestors of humans appear
Hunters which led to extinction of many large mammals

18. Holocene Epoch Includes present Great Lakes filled
Began when last ice age ended
As ice sheets melted, seas rose and coastlines took shape
Great Lakes filled
Modern humans developed agriculture and began to make tools