Earths Timeline
How old is the Earth
4.5 billion years old
What was Earth's surface like when it first formed?
A boiling ocean of lava
What are the first life forms called?
Single-celled bacteria
What is the name of the large landmass that formed 1.1 billion years ago?
Rodinia
What creature was the ancestor of all four-legged animals?
Tiktaalik
How many years did the Ice Age freeze the entire planet into a snowball?
15 million years
What two gasses would not allow anyone to breathe on early Earth?
Carbon dioxide and nitrogen.
What underwater features supported early life?
Hydrothermal vents (underwater smoke stacks)
What causes Earth’s tectonic plates to move?
Heat from the core moving the rock beneath the crust
What caused and where did it happen the biggest mass extinction on Earth 250 million years ago?
Volcanic eruptions in Siberia
How long ago did life first appear on Earth?
3.8 million years ago
What made Earth spin so fast that a day only lasted 6 hours?
The giant impact that formed the Moon
What is the name of the colonies of bacteria that used sunlight to make food?
Stromatolites
What is the name of the later supercontinent that formed?
Pangaea
Why were bugs like dragonflies and millipedes so huge in prehistoric times?
High oxygen levels allowed them to grow larger
How long did the asteroid bombardment that brought water to Earth last?
20 million years
How did Earth first get its water?
From meteorites that carried tiny droplets of water inside salt crystals
What important gas did stromatolites begin releasing into the atmosphere?
Oxygen
What process forms new ocean floor in the Atlantic?
Lava pushing up and cooling between tectonic plates
What wiped out the dinosaurs? Where did it originate?
A massive asteroid impact near the Yucatán Peninsula
How long ago did the dinosaurs go extinct due to the asteroid impact?
65 million years ago
What caused the global Ice Age that froze the planet 650 million years ago?
Carbon dioxide was absorbed by rocks, trapping less heat
What two things made it possible for life to move from water to land?
The formation of the ozone layer and evolution of seeds and eggs
What caused the Himalayas to form?
The collision of the Indian and Asian plates
How did mammals survive the dinosaur extinction?
They lived underground and ate a wide variety of foods