Radiometric age analyses using various radioisotopes withinmeteorites and moon r
ID: 1344 • Letter: R
Question
Radiometric age analyses using various radioisotopes withinmeteorites and moon rocks indicate that the Earth is approximately4.6 billion years old (for the calculations below, just use 4.5billion). Single-celled organisms evolved approximately 3.5billion years ago. However, multicellular life forms, withskeletons (shells) evolved about 540 million years ago, at thePrecambrian-Cambrian boundary (what we call the Cambrian Explosion– a huge increase in organisms found in the fossil record– refer to Figure 1.23 in your book). Dinosaurs evolvedabout 250 million years ago, and went extinct 65 million years ago. The Last Ice Age peaked 20,000 yearsago. Human civilization can be traced back only about5000 years.
If you compress all of geologic time (4.5 billionyears – 4,500,000,000 years) into a space the length of afootball field (Let’s say the zero yard line is thebeginning of geologic time; present time is the 100 yard line– the goal line), and using the information fromabove:
Explanation / Answer
Yes. your equation and answer seems correct.
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