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Journal Entry #4 – Earth’s History and Radiometric Dating

Journal Entry #4 – Earth ’ s History and Radiometric Dating

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Journal Entry #4 – Earth ’ s History and Radiometric Dating. Anchorage to Homer (or a brief history of the Earth). 226 Miles 4.6 Billion years. Mile 54 – 3.5 billion years ago. (Between girdwood and portage). First prokaryotic cells. Mile 128 – 2 billion years ago. (Seward-Homer split). - PowerPoint PPT Presentation

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Page 1: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Journal Entry #4 – Earth’s History and Radiometric Dating

Page 2: Journal Entry #4 –  Earth ’ s History and Radiometric Dating
Page 3: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Anchorage to Homer(or a brief history of the Earth)

226 Miles

4.6 Billion years

Page 4: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 54 – 3.5 billion years ago

• First prokaryotic cells

(Between girdwood and portage)

Page 5: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 128 – 2 billion years ago

• Eukaryotic cells• Free oxygen in the

atmosphere

(Seward-Homer split)

Seward Homer

Page 6: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 176 – 1 billion years ago

• Multi-cellular organisms

(Kasilof)

Page 7: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 196 – 600 million years ago

• First animals

(Ninilchik)

Page 8: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 202 – 500 million years ago

• Diversification of animals

(Cambrian explosion)• First land plants

Page 9: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 207 – 400 million years ago

• First insects• First amphibians

(Happy Valley)

Page 10: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 214 – 250 million years ago

• Dinosaurs!• First mammals

Anchor Point

Page 11: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 223 – 65 million years ago

• End of the dinosaurs• Earliest primates

(Just outside of Homer)

Page 12: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Mile 225 – 20 million years ago

• Diversification and spread of primates

Page 13: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

500 yds to go! – 6 million years ago

• Earliest hominids

Page 14: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

Sometime around 5-7 million years ago…

Orrorin tugenensis (Kenya) Laetoli, Tanzania

Page 15: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

500 ft! – 2 million years ago

• Beginnings of our genus Homo

• Earliest stone tools

Page 16: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

~ 2.5 - 2 MA…appearance of

our genus, Homo (Africa)

“Turkana Boy” – WT 15000

ER – 3733 (Kenya)

ER – 1470 (Kenya)

Oldowan Stone Tools

Page 17: Journal Entry #4 –  Earth ’ s History and Radiometric Dating

50 feet from end of Homer Spit – 200,000 years ago

• Earliest anatomically modern humans