Question

In this activity, you need to find reliable Internet sources that describe evidence of Earth's early history. You will also apply what you have already learned in the lesson. You need to find out how scientists estimate Earth's age and when the first life appeared. For example, scientists might try to find out the age of the oldest rocks and fossils, how modern living things might be like the first living things, and how the first living things changed the Earth system.

For this topic, you might find reliable information on websites operated by science magazines, natural history museums, or universities. Scientists who study rock layers, fossils, and Earth's history work at natural history museums and universities. Journalists who work at science magazines try to write about scientific discoveries in ways non-scientists can understand.
In Part 1, you will start by finding websites with information you can use. The questions in Part 2 will help you take notes. In Part 3, you will use the evidence you gathered to explain how scientists know how long it took life to appear on Earth after it formed.
Part 1: Identify Sources (5 points)
1. List at least five phrases from the Introduction that you can use in your search for sources. (2 points)







2. Identify three websites you will use to start your research. If you use other websites to complete the Research questions in Part 2, add them to this list. Cross out any websites that don't end up helping you complete the activity. (3 points)













Part 2: Research (20 points}
Use the websites you listed in Part 1 to answer the following questions. Remember to add any new sources you use to your list of sources.
1. About how old is Earth? (1 point)







2. Why is it difficult to find the first rocks that formed on Earth? (2 points)







3. How old are the oldest rocks on Earth? How did scientists determine their age? (2 points)







4. Why can scientists use zircon to find the age of the oldest rocks on Earth? (2 points)







5. What evidence supports the claim that Earth is older than the oldest rocks? (4 points)









6. What are the oldest fossils? How old are the oldest known ones currently accepted by scientists? (2 points)








7. Describe the living things that made the first fossils. (1 point)







8. How did the first fossils form? (2 points)










9. What evidence do today's organisms provide to support scientists' conclusions about the first fossils? (2 points)








10. How did the very early living things change Earth? Include evidence from the geologic record to support your answer. (2 points)










Part 3: Construct an Explanation (10 points)
Now you will use the evidence you gathered through your research. Explain how scientists use evidence to determine Earth's age and when life first appeared on Earth. Start by making a statement. Then support your statement with the evidence you gathered and logical thinking.
Statement about Earth's age and when life first appeared (2 points):








Evidence and reasoning (8 points):

Answer 1

It seems like you have a school assignment to complete. I can help you with your research by providing information on the topics you mentioned. Here are five phrases from the introduction that you can use in your search for sources:

1. Earth’s early history

2. Estimate Earth’s age

3. First life appeared

4. Oldest rocks and fossils

5. Modern living things

Part 2:

According to scientific estimates, Earth is about 4.54 billion years old, plus or minus about 50 million years. Scientists have used radioactive dating techniques to determine the approximate ages of Earth’s oldest known rocks and minerals.

It is difficult to find the first rocks that formed on Earth because Earth’s oldest rocks have been recycled and destroyed by the process of plate tectonics. The rocks containing signs of early life have been deformed and metamorphosed by heat, stress, and hydrothermal alteration and then subject to billions of years of weathering processes such as erosion.

The oldest rocks on Earth are more than 4 billion years old and were formed during the Hadean Eon of Earth’s geological history. The Acasta Gneiss, found in northwestern Canada, is one of the oldest known rocks on Earth and has been dated at 4.03 billion years old. Even older than the Acasta Gneiss are individual zircons from the Jack Hills in Australia, dated to 4.4 billion years ago. Scientists determine the age of rocks using various dating techniques.

Scientists use various techniques to determine the age of rocks. One way is by determining the age of the group of rocks, or formation, that a rock is found in. The age of formations is marked on a geologic calendar known as the geologic time scale.

Another way scientists determine the age of rocks is by using radioactive dating techniques. This involves measuring the number of radioactive isotopes in a rock sample and using that information to calculate the age of the rock.

Radioactive dating techniques take advantage of the fact that certain isotopes of elements are unstable and undergo radioactive decay at a known rate. Scientists can measure the amount of a radioactive isotope and its decay products in a rock sample and use that information to calculate the age of the rock.

For example, uranium-lead dating involves measuring the amount of uranium and lead isotopes in a rock sample. Uranium isotopes decay into lead isotopes at a known rate, so by measuring the ratio of uranium to lead isotopes in a rock sample, scientists can determine how long it has been since the rock formed.