13.1 Precambrian Time: Vast and           Puzzling
Shields• A large, relatively flat expanse of ancient  metamorphic rock within the stable  continental interior
Stromatolite• Structure produced by algae trapping  sediment and forming layered mounds of  calcium carbonate
Key Concept• The Precambrian encompasses immense  geological time, from Earth’s distant  beginnings 4.56 billion years ago...
Key Concept• Earth’s original atmosphere was made up of  gases similar to those released in volcanic  eruptions today- wat...
Key Concept• Later, primitive organisms evolved that used  photosynthesis and released oxygen
Key Concept• Oxygen began to accumulate in the  atmosphere about 2.5 billion years ago
Key Concept• Much of what we know about Precambrian  rocks comes from ores mined from shields.
Upcoming SlideShare
Loading in …5
×

Earth science 13.1

2,126 views

Published on

Published in: Education, Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
2,126
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
4
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Earth science 13.1

  1. 1. 13.1 Precambrian Time: Vast and Puzzling
  2. 2. Shields• A large, relatively flat expanse of ancient metamorphic rock within the stable continental interior
  3. 3. Stromatolite• Structure produced by algae trapping sediment and forming layered mounds of calcium carbonate
  4. 4. Key Concept• The Precambrian encompasses immense geological time, from Earth’s distant beginnings 4.56 billion years ago until the start of the Cambrian period, over 4 billion years later
  5. 5. Key Concept• Earth’s original atmosphere was made up of gases similar to those released in volcanic eruptions today- water vapor, carbon dioxide, nitrogen, several trace gases, but no oxygen.
  6. 6. Key Concept• Later, primitive organisms evolved that used photosynthesis and released oxygen
  7. 7. Key Concept• Oxygen began to accumulate in the atmosphere about 2.5 billion years ago
  8. 8. Key Concept• Much of what we know about Precambrian rocks comes from ores mined from shields.

×