« previous next »

Author Question: Why is it that scientists know less about the first four-fifths of Earth's history than about the ... (Read 152 times)

ap345

  • Hero Member
  • *****
  • Posts: 537
on: Jul 16, 2018
Why is it that scientists know less about the first four-fifths of Earth's history than about the last, most recent one-fifth?
 
  What will be an ideal response?

Question 2

Assuming that humans went extinct today, do you think that they would be good index fossils? Why or why not?
 
  What will be an ideal response?


dyrone

  • Sr. Member
  • ****
  • Posts: 322
Reply #1 on: Jul 16, 2018
Answer to Question 1

Answer: The short answer is that the farther back in time, the fewer the clues that remain because of two major factors: 1) Precambrian rocks (which make up 88 percent of Earth's history) have been intensely deformed, so evidence was destroyed, and 2) the first abundant fossil evidence does not appear until the beginning of the Cambrian period.

Answer to Question 2

Answer: Yes. Modern humans have only existed for 100,000 years and are geographically widespread.


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
« previous next »
 

Did you know?

The most common childhood diseases include croup, chickenpox, ear infections, flu, pneumonia, ringworm, respiratory syncytial virus, scabies, head lice, and asthma.

Did you know?

Methicillin-resistant Staphylococcus aureus or MRSA was discovered in 1961 in the United Kingdom. It if often referred to as a superbug. MRSA infections cause more deaths in the United States every year than AIDS.

Methicilli ...
Did you know?

Most strokes are caused when blood clots move to a blood vessel in the brain and block blood flow to that area. Thrombolytic therapy can be used to dissolve the clot quickly. If given within 3 hours of the first stroke symptoms, this therapy can help limit stroke damage and disability.

Did you know?

Pregnant women usually experience a heightened sense of smell beginning late in the first trimester. Some experts call this the body's way of protecting a pregnant woman from foods that are unsafe for the fetus.

Did you know?

The first war in which wide-scale use of anesthetics occurred was the Civil War, and 80% of all wounds were in the extremities.

Animation of the apparent retrograde motion of Mars in 2003 as seen from Earth Animation of the apparent retrograde motion of Mars in 2003 as seen from Earth
Planets, Earth and Moon Planets, Earth and Moon
William Masters and Virginia Johnson are among the most influential researchers in the history of th William Masters and Virginia Johnson are among the most influential researchers in the history of th
The Arctic is warming faster than any other region on Earth The Arctic is warming faster than any other region on Earth
Earth-Moon-Sun Positions during the Spring Tide Earth-Moon-Sun Positions during the Spring Tide
History History
Video: Coronary Heart Disease

For a complete list of videos, visit our video library