Geological time scale(Oct.20)

Question 1

Estimated age of the Earth.

Answer 1

4.55 billion years ago

Question 2

How many eras are there on the geological time scale? Name all of them IN ORDER and how long they lasted.

Answer 2

There are 4 eras:

• Precambrian era, lasted 4 billion years
• Paleozoic era, lasted 300 million years
• Mesozoic era, lasted 185 million years
• Cenozoic era, lasted 65 million yrs and still happening

Question 3

Precambrian era, 5 elements.

Answer 3

• For the first 1000 million yrs, the solar system & the Earth were formed
• First life forms; prokaryotes(no nuclei) and bacteria
• Bacteria that can do photosynthesis and release oxygen into the atmosphere
• Eukaryotes(cells with nucleus); worms, soft coral and jellyfish
• Ediacaran fauna; animals capable of digesting and reproducing

Question 4

Paleozoic era, main 5 elements

Answer 4

• Appearance of first amphibians(they get out of water)
• Appearance of first trees(ferns and horsetails)
• Major extinction caused 70% of marine species to disappear
• First connifers and first small reptiles
• Largest mass extinction caused by glaciation, volcanic eruption, acid rain, destruction of ozone layer, 96% of marine species and 75% of land species disappear

The last mass extinction marks the end of this era

Question 5

Mesozoic era(age of reptiles), 6 elements

Answer 5

• Warm climate made large reptiles appear
• Appearance of dinosaurs
• Mass extinction due to meteorite impact or volcanic eruptions cause 50% of marine life to disappear
• First birds and small mammals start to appear
• First flowering plants appear
• Mass extinction due to meteorite in Mexico, this caused the disappearance of dinosaurs(end of era)

Question 6

Cenozoic era(current era), 3 elements

Answer 6

• Mammals continue to thrive
• Appearance of Megafauna(very large mammals)
• Appearance of primates and hominids