Download Geologic Time Guided Notes

Name: _______________________________________________________ Date: _________ Period: ______
Geologic Time Guided Notes
Academic Science
** Geologic time is divided into large blocks based on:
____________________________________________ that dominated the Earth at that time**
PRECAMBRIAN TIME (4.6 billion years ago – 543 million years ago)
- Longest and most unknown/most debated
Early Earth:
 Atmosphere made of gases such as ______________________________,
______________________________, and ___________________________

Place of turmoil –
_________________________________________________________________________

Unpleasant environment for __________________________
Early Life:
 Hypothesis – Life developed from ___________________________in the ocean and atmosphere
o HOW?
 Radiation caused _________________________________________________
that made life possible


These molecules joined to _______________________________
Since the early atmosphere did not contain oxygen the first organisms were
___________________________ which are _______________________________, do not
contain a_____________________, and do not require ___________________________
Photosynthesis and Oxygen:
 Stromatolites are huge colonies of _________________________________________
o What is cyanobacteria?
 _____________________________________________________________
___________________________________________________________
 Photosynthesis releases _________________________ into the oceans and air
 The ozone layer begins to form and reduce the amount of ___________________________
Multicellular Organisms:
 After 1 billion years (3.6 BYA), larger organisms (______________________) appear in the
fossil record

Eukaryotes contain a ________________________ and other
_____________________________________________________________
PALEOZOIC ERA (543 million years ago – 248 million years ago)
- Considered relatively recent compared to Precambrian time
- Means “ancient life”
-Cambrian Explosion – most organisms appear in this era
Life:
 Fossils of___________________, ____________________________,
_____________________________, _____________________________,
_______________________________
 Early backboned organisms (__________________________________) appear
 __________________________________
Move to land:
 Plants, fungi, and air-breathing animals colonize land
 All major _________________________ groups except _________________________ plants
 Towards the end of the era
______________________________________________________________________ appear
Mass Extinction:
** One of the largest ______________________________________ occurs and _____% of Paleozoic
organisms become extinct**


Entire _____________________________________________, such as trilobites are extinct
_________________________________________________________
MESOZOIC ERA (248 million years ago – 65 million years ago)
- Means “middle life”
- Known as the “_________________________________”
Life:
 __________________ roamed for 150 million years of the Mesozoic Era
 Giant ____________________________ in the ocean
 The first ____________________________
 Plants included __________________________ and ___________________________
plants
Mass Extinction of the Dinosaurs:
 At the end of the Mesozoic Era there was a _________________________________
o _______________________________ went extinct
o Many other plants and animals
CENOZOIC ERA (65 million years ago – Today)
- Means “recent life”
- More information about this era than any other
- Known as the “___________________________________________”
Life:
** The fossils from the Cenozoic Era are formed recently in geologic time so they are found in
rock layers closer to the Earth’s surface **
 Early mammals were _____________________________________________________
 Later in the era there were _______________________________________________
 Birds, insects, and flowering plants
Climate:
 Climate has __________________ several times during this era
 ________________________________ covered the Earth with sheets of ice causing
__________________________________________ and ______________________ of
organisms
STOP AND SUMMARIZE
Go back through your notes and determine any major geological and biological events.
Time Period/Era
Precambrian
Paleozoic
Mesozoic
Cenozoic
Major Events