Name_________________________
How The Earth Was Made – Season 2
Birth of the Earth
Segment 1: Major Challenge
1. Why is so difficult for scientists to find clues on the birth of the Earth?
Erosion, volcanic activity, shifting plates
2. What did investigators find at Meteor Crater in Arizona?
Meteorites are older than any rocks on Earth
More than four and half billion years ago our Sun came into existence. It is surrounded
by a swirling mass of dust.
3. Describe theory of formation of solar system from this dust.
4.5 billion years ago our young sun surrounded by a cloud of gas and dust, as it
cooled grains and minerals formed that bumped into each other to form planets
4. What was the problem with the theory?
Lack of evidence to explain how materials would clump together
Evidence
In 2003, aboard the Space Station a researcher was observing what happens to various
materials in the zero gravity of space.
5. What did he observe regarding salt grains?
Salt grains in plastic bag particles immediately began to stick to each other
through electrostatic charges.
6. What did scientists then conclude regarding other mineral grains?
If salt sticks together in space then so could mineral grains in the dust cloud
around the sun.
Evidence
7. Stony Meteorites – What do planetary scientists find in them?
Pieces of everything that was in the dust cloud
8. Gradual growth of these rocky aggregates, at .5 mile across what critical event
happens?
The planet accumulates enough mass that gravity takes control and pulls in
surrounding rocks even faster.
Our Earth becomes one of the largest rocks so for 30 million years there is a continuous
bombardment resulting in a random accretion. However, geologists know Modern Earth
is not like that. Something must have happened.
9. Draw and describe the layers of the Earth
Crust – thin rocky
Mantle – rock layer, hot but not melted
Core – Iron & Nickel
Layers of Earth are a clue to Earth’s formation
Name_________________________
How The Earth Was Made – Season 2
Birth of the Earth
10. What extraordinary event occurred to transform the interior?
Complete meltdown
11. How were core and layers formed?
Denser elements sank to core
12. What force was responsible for the creating the core and the layers?
Gravity
13. What caused the heat up?
Incorporation of very hot radioactive elements
14. Describe the Earth, 30 million years after it began to form.
Earth was totally molten, magma oceans were 2000 degrees C and at the edge
of the planet space is -450 degrees C
15. With the vast temperature difference what happens?
Surface cannot stay molten long and Earth cools from the outside in. In less than 1
million years a thin crust is formed.
16. However, volcanoes spew __lava_____________ and ___gases____________.
Meteorites rain down in constant bombardment.
** Evidence in Review**
1. Salt grains provide evidence that mineral particles in the dust cloud clumped
together to form the Earth
2. Layers of the Earth provide evidence that the Earth completely melted
shortly after it formed.
17. What vital piece of information did scientists still not know?
Age of Earth
Segment 2: Age of the Earth
18. In ___1650______, Irish Archbishop adds up all the ages of prophets and kings in the
Bible and concludes the Earth was born at nightfall before Sunday October 23,
__4004____ BC. A century later geologists find that sediments and volcanic lavas were
laid down over millions of years not thousands. In ___1897_____, physicist Ernest
Rutherford figures out how to use radioactive decay to determine age of rock. Some
samples are found to be billions of years old.
19. What’s the next major obstacle?
It’s hard to find rocks from these early days due to erosion, continental drift, and
tectonic activity
20. What new type of investigation does C.C. Patterson take?
Dating meteorites
21. Explain the logic behind dating meteorites to determine the age of the Earth.
Since meteorites were formed at same time as Earth they must be the same
age. At Meteor Crater meteors are found that date to 4.5 billion years old
meaning Earth must also be that old
22. Since then modern techniques have refined the age of the Earth to ___4.6 _billion
years.
Scientists now knew how and when the Earth was formed.
What happened next?
Name_________________________
How The Earth Was Made – Season 2
Birth of the Earth
23. Hardman was researching the origin of the Moon. Summarize the radical new theory
proposed by Bill Hardman in 1974.
Intense impacts blew crust/mantle rock off of Earth, planet size of Mars crashed
into Earth forming Earth and moon
Evidence
Video footage of astronaut collecting moon rocks in 1972.
24. Why still under lab conditions?
Don’t want humans leaving organic material on it
Originally Moon’s formation was thought to be like Earth’s formation from
accretion with layers and an iron core.
25. What happened when the rocks from the 1972 Moon footage were examined and
analyzed?
Moon rocks had less iron than expected.
26. How did Hartman interpret this data?
Indicated that the conventional theory about Moon’s formation was wrong- moon
made out of material from Earth’s crust and upper mantle
** Evidence in Review**
3. Radiometric dating provides evidence that the earth is about 4.6 billion years old
4. Lack of iron in moon rocks provides evidence that it was not formed at the same
time as the Earth. Earth survived a Giant Impact.
Segment 3: Earth still missing 2 essential components
1. Solid land
2. Water
Earth forms from dust cloud surrounding Sun and then survives huge collision with
another planet about size of Mars. Jump forward about 200 million years.
27. Northeast shore of Hudson Bay Canada, what caught ONeill’s eye?
The rocks looked different from the other rocks. They were highly altered,
deformed volcanic lavas called amphibolites.
Chemistry and mineralogy were unusual
28. What were the results of the radiometric dating?
Results = Amphibolites formed 4.3 billion years ago
Unbelievable! Redid the test 3 times did with additional samples
29. Why are these results so unbelievable?
These are the oldest rocks found on Earth, this is the closest we’ve come to
finding Earth’s original crust.
30. What clues/evidence do the amphibolites provide about the thickness of the crust 4
billion years ago?
The amphibolites were created at least 12 miles underground, crust that thick
says there must have been continents 4.3 billion years ago.
Name_________________________
How The Earth Was Made – Season 2
Birth of the Earth
This rock sequence was formed deep underwater based on its chemical signature.
31. Additional evidence comes from same sequence, what do geologists find?
Banded iron formation
32. What is banded iron formation?
Alternating bands of light silica and dark bands called magnetite
33. Why is this considered to be evidence of water’s presence of Earth more than 4
billion years ago?
Magnetite in banded iron formations only form underwater. Therefore, oceans
also existed 4.3 billion years ago.
** Evidence in Review**
Early Earth 4.3 billion years ago had oceans and continents based on
5. Amphibolites tell us Earth had a thick crust meaning continents existed.
6. Banded iron formations show oceans existed at same time
Segment 4: Where did all the water come from?
34. Why do scientists believe the answer lies in space?
New evidence from a meteorite that fell in 1998 but only recently has been
analyzed.
35. What did scientists find in the meteorite?
Grains of table salt. Trapped inside salt crystals were small droplets of liquid
water.
36. How old is the salt and therefore the water?
Salt dated 4.5 billion years, so water has to be at least that old, since it’s inside the
salt. Therefore, water is as old as the solar system.
37. Describe how scientists believe all the water we have on Earth arrived here.
Meteorites brought water to Earth, over the course of billions of years of
bombardment droplet by droplet.
Segment 5: Last Phase
With water and continents present stage is set for last phase of Earth’s development
38. Without life what would not exist in terms of geologic features?
Sedimentary rock formations like chalk and limestone
Coal, oil or natural gas
New explanation
39. In the desert of northern Mexico (Allende) what happened that turned night into day?
Large meteorite/fireball- size of car traveling at 36,000 mph entered Earth’s
atmosphere and broke into thousands of pieces, showering of stones over a 5 mile
area.
40. What did samples reveal?
Tiny amounts of amino acids, chemical building blocks of life.
Name_________________________
How The Earth Was Made – Season 2
Birth of the Earth
41. What had the scientific world believed about the formation of amino acids before the
discovery of the Allende meteorite?
Chemical reactions in warm pools or through lightening causing chemical
reactions in the atmosphere.
** Evidence in Review**
Meteorites
7. Water arrived here in meteorites
8. Meteorites also brought amino acids
Segment 6: one more piece. 3.5 billion years ago new forms of life are about to emerge.
42. What element is not present but required for life as we know it?
Oxygen
43. What gases made up the atmosphere at that time?
sulfur, methane, sulfuric acid, carbon dioxide
44. What are stromatolites?
Fossilized remains of corral-like creatures found in rocks all over the world. They
provide clue as to how atmosphere changed.
45. Where can living stromatolites be found?
In the northern Mexican desert-- Cuatro Cienegas
3.5 billion years ago Earth was dominated by microbes: Cyanobacteria
Stromatolites are made up of millions of Cyanobacteria
46. What ‘s so special about the Cyanobacteria?
Cyanobacteria produce oxygen (bubble under water). They use sunlight and
water and release Oxygen
Over time trillion of tons of oxygen changes way all life evolves.
47. What are some of the impacts that life has had on geology?
Decaying plant matter built up compressed layers that form all coal, oil and
natural gas
Sedimentary rocks form from skeletons of marine organisms (limestone & chalk)
Evidence
1.
2.
3.
4.
5.
Salt grains provide evidence that mineral grains in the solar dust cloud
clumped together to form planets
Meteorites provide evidence that Earth formed 4.5 bya
Oldest rocks provide evidence that continents and oceans formed 4.3
bya
Liquid water in meteorites provide evidence that water was brought drop
by drop during billions of years of meteor showers
3 billion years ago Earth had continents, oceans, oxygen and primitive
life forms.
Name_________________________
How The Earth Was Made – Season 2
Birth of the Earth
Event
1. The Earth formed by dust
and minerals sticking
together in the nebula
2. The Earth completely
melted from radioactive
elements
3. The Earth and the whole
solar system formed about
4.6 billion years ago
4. The Earth survived a
giant impact
Evidence
Salt sticks together in space,
so minerals and dust must
too.
The Earth has internal
layers: core, mantle, and
crust
Radiometric dating of
meteorites
Moon rocks are low in iron,
so must be formed from
Earth’s crust material that
got knocked off
5. A thick crust and
Amphibolite rocks only form
continents formed 4.3 billion 12 miles deep and they are
years ago
4.3 billion years old.
6. Oceans formed 4.3 billion Banded Iron formations only
years ago
form under water and they
are 4.3 billion years old
7. Water came from space
Salt in meteorites contains
in meteorites, drop by drop water droplets, and the salt is
4.5 billion years old
8. Amino acids, a building Amino acids were found in
block of life, came from
meteorites 4.5 billion yearsrs
space
old
9. The Earth’s atmosphere
3.5 billion year old
changed from toxic to
stromatolite fossils show that
oxygen, allowing advanced cyanobacteria began to
life to develop.
create oxygen gas.