1. The Precambrian Time Felipe González. María Alejandra Vargas.
Valentina Stozitzky.
Daniela Ramos.
Daniel Pérez.
10B

2. 4.5 billon years ago

3. The earth was born!!!

4. Geologists and paleontologists

5. Stop! Notice fabulous table on your book
Geologic time scale
-relative, absolute dating.
-major divitions of the geologic time scale.
Eons
Era
Periods

6. PRECAMBRIAN 90% It means before the “cambrian period”.
Before the formation of rocks with recognizable fossils.
term was originally used to refer to the whole period of earth's history 
there are some hard-to-discern fossils in some Precambrian rocks
"crypt" = "hidden," and "zoon" = "life“
It covers almost 90ofthe entire history of the earth
Cryptozoic or "obscure life“.
90%

7. Divided into three Eons
Hadean
Archean
Proterozoic

8. Precambrian Environment
The atmosphere was reduced into gases and oxygen.
Scientist think that seas were created by a volcanic catalist.
Oxygen had chimical reactions: Iron and oxidable surfaces.
The planet had a redish tint.
The planet developed a solid crust that created water vapor.
Oxygen began to be produced in large quantities.
The seas had a green bright tone.
When evolving life forms developed photosynthesis, oxygen began to be produced in large quantities, causing an ecological crisis sometimes called the Oxygen Catastrophe.
Older rocks contain massive banded iron formations that were apparently laid down as iron and oxygen first combined

9. Important info… Scientists think the first seas gave rise to life.
hot, mineral-rich volcanic vents actied as catalysts for chemical reactions .
The water bubbles that formed-1st cell membranes.
Other bubbles contained self-replicating substances.
chemicals around them combined to produce energy-using, living cells.

10. Forms of life
The first living organism were microscopic bacteria founded in fossils.
Fossilized bacteria and blue-green algae 3,500 million years ago.
Eukaryotic cells2,100 million years after.
Protozoa.
Invertebrates.
Found mainly in the oceans.
Evolved later on (700 million years ago)
Sponges, corals, jelly fish

11. Formation of the Solar System
HADEAN EON
From 4567 to 3800 mya.
Splashh!
The big bang
Formation of the Solar System
Formation of the Earth.
Moon is created.
Oceans of liquid rock, boiling sulfur, and impact craters everywhere.
The air is hot, thick, steamy.
No oxygen
-water vapor.
-carbon dioxide.
No rocks of this time have been found.

12. ARCHAEAN EON
From 3800 to 2500
Surface of the Earth     molten solid rock.
Water condensed in liquid form.
1st Prokaryotes appeared.
15 hours long.
-oxygen producing bacteria.
- cyanobacteria (blue-green algae).
The continents have not formed yet. (global ocean)
Atmosphere (75% nitogen,15% carbondioxide.)

13. Start of Huronian ice age.
PROTEROZOIC EON
Divided in Era and Periods
Paleoproterozoic Era    Siderian Period  - Stable continents first appeared.
free oxygen is found     -oceans and atmosphere.
Oxygen catastrophekilled many organisms.
Start of Huronian ice age.
From 3800 to 2500

14. PROTEROZOIC EON Rhyacian Period
From 3800 to 2500
Rhyacian Period
 - Organisms with mitochondria     capable of aerobic respiration appear.
Orosirian Period  - Mountain development  - Oxygen starts accumulating in the atmosphere
Statherian Period
-single-celled life appeared.  - lots of bacteria and archaeans.

15. PROTEROZOIC EON From 3800 to 2500
Mesoproterozoic Era     Calymmian Period )  - Oxygen builds up in the atmosphere.  - Formation of ozone layer.  -  Eukaryotic (nucleated) cells appear.
From 3800 to 2500
Ectasian Period   - lots of green (Chlorobionta) and red (Rhodophyta) algae.
Stenian Period  -  Spore-gamete formation  sexual reproduction.  -  Formation of the supercontinent.

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