The Origin of our Solar System and the Earth

It’s in the stars…

• Nebula – an interstellar cloud of dust, hydrogen gas, helium gas and other ionized particles.

• The gas, dust and other materials in the nebula collide and condense to form a larger mass, this process produces a great deal of heat, thus the star is formed.

• Due to the gravitational pull of the star, the remaining nebula organizes itself into accretion discs (rings of dust and gasses).

Orion Nebula

Eagle Nebula

Solar Nebular

Hypothesis

EARTH’S EARLIEST TIME:

THE PRECAMBRIAN

Earth’s formation, along with the other planets,

is projected to have happened 4.6 billion years ago

from a solidified cloud of dust and gasses left over from the creation of

the Sun.

THE FIRST EON: HADEAN

•Earth's formation by accretion from the solar nebula, 4.6 billion years ago

•bombardment by meteorites

•volcanism must have been severe

•Earth changed from liquid to solid

THE SECOND EON: ARCHEAN

•3.8 to 2.5 billion years ago

•Earth cooled significantly

•An atmosphere formed which lacked oxygen and an ozone layer but likely contained methane, ammonia, and other gases which would be toxic to most life on our planet today.

•primordial life began to evolve: stromatolites, such as cyanobacteria (blue-green algae) and archea (bacteria that can survive in extreme conditions)

Stromatolites

Heterocyst – Nitrogen Fixation

Photosynthetic Cells

Cyanobacteria

THE THIRD EON: PROTEROZOIC

•started 2.5 billion years ago and ended 543 million years ago

•stable land masses first appeared

•oxygen build-up in the atmosphere

•prokaryotic bacteria and the four eukaryotic kingdoms (plants, animals, fungi, & protists)

•end of proterozoic: first soft-bodiedanimals (fossil evidence)

Precambrian (4,500 to 543 mya)

- 3.96 billion yrs

Proterozoic Era(2500 to 543 mya) - 1.96 billion yrs

Archaean Era(3800 to 2500 mya)- 1.3 billion yrs

Hadean Era (4600 to 3800 mya) – 800 million yrs

You can think of the Precambrian time as the earliest time of earth formation and the first forms of life on it. You can liken it to a pregnancy in which basic elements and life forces form the infant.

Once the infant is born, we speak of a human life time.

Earth’s Life Time is called the PHANEROZOIC EON.

Earth’s life time can be divided into

old age, medieval (middle) age, and young age

Paleozoic Mesozoic Cenozoic

Phanerozoic Eon (543 mya to

present)

Cenozoic Era -young age-

(65 mya to today)- 65 million yrs

Period:Quaternary (1.8 mya to today)Tertiary (65 to 1.8 mya)     

Mesozoic Era -middle age- (248 to 65 mya)- 183 million yrs

Cretaceous (144 to 65 mya)Jurassic (206 to 144 mya)Triassic (248 to 206 mya)

Paleozoic Era -old age-

(543 to 248 mya)-295 million yrs

Permian (290 to 248 mya)

Pennsylvanian (323 to 290 mya) Mississippian (354 to 323 mya) (Carboniferous)

Devonian (417 to 354 mya)Silurian (443 to 417 mya)Ordovician (490 to 443 mya)Cambrian (543 to 490 mya)       

Paleozoic Era -age of old life-

(543 to 248 mya)

7 Periods:Permian (290 to 248 mya)Pennsylvanian (323 to 290 mya) Mississippian (354 to 323 mya) Devonian(417 to 354 mya)Silurian(443 to 417 mya)Ordovician (490 to 443 mya)Cambrian (543 to 490 mya)   

Carboniferous

What happened in the Paleozoic Era?

• 90% of all marine animal species became extinct (oil and limestone)

• tremendous mountain building (platechtonic movement)

• retreats of shallow seas

• abundance of primitive plants in the Carboniferous time

• trilobites were abundant and then became extinct

• Pangaea formed, Panthalassa, Tethys Sea

Paleozoic Era

Trilobites!

PANGAEA = one continent

PANTHALASSA

TETHYS SEA

Mesozoic Era -age of medieval life- (248 to 65 mya)

3 Periods:Cretaceous (144 to 65 mya)Jurassic (206 to 144 mya)Triassic (248 to 206 mya)

What happened in the Mesozoic Era?

• dinosaurs evolved in the Triassic

• dinosaurs diversified until the Jurassic

• dinosaurs became extinct by the end of the Cretaceous

(last dinosaurs to have lived are found in the late Cretaceous deposits of Montana in the United States

• fauna changed: trees and flowering plants appeared

• tectonic plates move to present location

The Age of Reptiles

Mesozoic Era

Cenozoic Era -age of young life-(65 mya to today)

2 Periods:

Quaternary (1.8 mya to today)

Holocene (10,000 years to today)

relative warm period; homo sapiens sapiens

Pleistocene (1.8 mya to 10,000 yrs)

humans spread in the world

most continents covered with glaciers= ice age

mammoths prevalent and then extinct

Tertiary (65 to 1.8 mya)

Pliocene (5.3 to 1.8 mya) Antarctic polar cap formed

Miocene (23.8 to 5.3 mya) many grasses; kelp forests

Oligocene (33.7 to 23.8 mya) first elephants with trunks, early horses

Eocene (54.8 to 33.7 mya)

small hoofed animals (ungulates)

Paleocene (65 to 54.8 mya)

starting point for the great evolution of mammals

Cenozoic Era

The Breakup of Pangaea

Break-up of Pangaea in the different Eras:

LAURASIA BREAKS UP

GONDWANALAND BREAKS UP

PANGAEA BREAKS INTO LAURASIA and GONDWANALAND

One supercontinent: PANGAEA