lesson 2: ancient earth. essential questions how did gravity affect earth’s formation? how did...
TRANSCRIPT
LESSON 2: ANCIENT EARTH
Essential Questions
How did gravity affect Earth’s formation? How did the oceans and atmosphere
form? What conditions made early Earth able
to support life? How did environmental changes affect
the evolution of life?
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Vocabulary
Hadean eon Archean eon Protocontinent Proterozoic eon Thermal energy
Earth’s Earliest History
Gravity and the Solar System Before Earth or even the solar system
existed, a cloud of gas, ice, and dust, called a nebula, floated in space
Earth’s Earliest History
First: Gravity pulled the particules together into a flattened disk shape and began to rotate.
Second: the material in the center became dense and the Sun formed
Third: the remaining pieces of material in the disk attracted each other and planets were formed
Spherical Earth
As more particles come together Earth became larger. Thermal energy is produced by collisions,
which warmed the planet. Asteroids continued to crash into the Earth
surface, making it even hotter.
Hadean Eon, Archean Eon, Proterozoic Eon
The first 640 million years of Earth history
Hadean Eon
Hadean Eon
The first 640 million years of Earth history
Formation of Earth’s Core A hot Earth cools Seas of Molten Rock Changes in the Seas The Ancient Athmosphere
From about 4 to 2.5 billion years ago
Archean Eon
Archean Eon
Earth continues to cool and first solid surface appeared, but still twice as much internal thermal energy was produced at that time, comparing to nowadays.
Volcanic Activity As magma rised to the surface through cracks in the ocean floor it
has formed Earth first oceanic crust. The Earliest Continents
Protocontinents: small and early continents which have collided between each other forming bigger landmasses
Earth’s Oceans Form Fossil bacteria and stromatolites are the earliest evidence of life
present in rocks. They are uncommon and difficult to see due to their microscopic size.
The Archean oceans were extreme environments, most organisms alive today would not have survived then.
From 2.5 to 0.542 billion years ago
Proterozoic Eon
Proterozoic Eon
Changes in the Atmosphere: Earth was cooling down and larger landmasses were formed. Increase in Oxygen Snowball Earth
Supercontinents and Shallow Seas Proterozoic Life
Unicellular organisms in water. First multicellular organisms in the ocean, but had
no hard parts, so fossils aren’t abundant.
Homework
Textbook: Page 94 #2, 3, 4 Workbook: Page