1. Evolution of Earth and Life
ESC 102
Evolution of Earth and Life
Historical
Geology
Spring 2011
This is ESC 102 Evolution of Earth and Life

2. Earth Systems can you identify them?
When we view the Earth from space what Earth systems are observable?
What is most obvious?
Are these systems independent or do they interact with one another?
What is the first thing you notice when you view the Earth from space?

3. Systems = Spheres of the Earth
Lithosphere: Earth’s solid rocky mass
Hydrosphere: All of earth’s water
Atmosphere: The thin gaseous layer above Earth’s surface
Biosphere: All of earth’s life forms
Earth’s spheres definitely interact.
Give an example of the interaction of two or more spheres.

4. Three Themes tell the story of the evolving Earth
The Theory of Plate Tectonics
Solid Earth is composed of plates that move over Earth’s surface.
The Theory of Organic Evolution
Earth’s biota – all living things – has evolved or changed through history.
The Geologic Time Scale
Geologic processes take place within extensive geologic time -~ 4.6 billion years of Earth’s history.

5. Something Happened…..
James Hutton observed tilted sedimentary layers overlain by near-horizontal layers. He realized that whatever processes created this rock outcrop must have taken millions of years. In 1785, published his Theory of the Earth and is considered founder of modern geology.

6. Charles Lyell wrote “Principles of Geology in 1830.
He furthered the work of James Hutton: concept of Uniformitarianism
Rock layers reveal sequences of events based on processes that occur today.

7. Historical Geology applies geologic principles to help predict and explain Earth’s materials
William Smith was an English surveyor who realized that rock types and fossils occur in repeated patterns. He was able to predict rock sequences that would be encountered in constructing canals
Smith mapped the geology of much of England. (1815)

8. Smith’s map took many years to complete and helped establish the geologic time scale.?

9. Hypothesis or Theory?
The scientific method brings an orderly and logical approach to decoding geologic evidence.
A hypothesis is a tentative explanation for observations
Scientists make predictions using hypotheses – then they are tested
After repeated testing, a theory may be proposed
Some phenomena cannot be tested or explained

10. A theory is formed A theory is more than an “educated guess”
A theory explains natural phenomena and may relate several observations
A theory is well-tested and well-supported by objective evidence
Examples include: Plate Tectonics Theory Theory of Organic Evolution

11. Where do scientists look for evidence for the following?
The origin and age of the universe
The origin and age of the solar system
The origin and age of the Earth and Moon
The origin of life on Earth
Evidence of plate movement on Earth
Explanation for large scale extinctions on Earth

12. How old is the universe?
When? Scientists believe the universe was formed about 15 billion years ago
How? The Big Bang is a model for the “beginning” of the universe
“Show me”! What is the evidence?

13. Evidence of the Big Bang
Pervasive background radiation of 2.7o C
above absolute zero is observed in space (-273o C or -460o F)
“Afterglow” of the Big Bang discovered in As predicted, it was cosmic microwave radiation from .space
Fahrenheit absolue zero ~ 460 degrees Glow was predicted and discovered in 1965 by Penzias and Wilson (nobel prize)

14. Evidence of the Big Bang
Galaxies moving away – expanding universe (proposed by Hubble)
Imagine the surface of a balloon as it is inflated. Locations
on the surface move
away from one another.ther.

15. Evidence of the Big Bang
Determine the Age of the Universe
Determine rate of expansion “Back-model” to a time when the galaxies would be together in the same space

16. Research
A 7 year satellite observation project mapped the cosmic microwaves in space
Revealed the nature of many components that had been predicted in various models.
The WMAP project since 2002 has enabled scientists to refine the age of the universe to 13.7 billion years and the “shape” of its surfaces.

17. Enormous expansion occurred
Big Bang model
Initial state: NO time, NO matter, NO space
Universe was pure ENERGY
During the FIRST second of time:
--very dense matter came into existence
--The four basic forces separated:
gravity electromagnetic force strong nuclear and weak nuclear forces
Enormous expansion occurred

18. Big Bang Model 300,000 years later: Next 200 million years:
Atoms of hydrogen and helium formed
Light (photons) burst forth for the first time
Next 200 million years:
Continued expansion
Stars and galaxies began to form
Elements heavier than hydrogen and helium began to form within stars by nuclear fusiion

19. The formation of the solar system
9 billion years later…..

20. Origin of Our Solar System
Solar nebula theory
cloud of gases and dust formed a rotating disk
condensed and collapsed due to gravity
forming solar nebula
with an embryonic Sun
surrounded by a rotating cloud

21. Embryonic Sun and Rotating Cloud
Planetesimals have formed
in the inner solar system,
and large eddies of gas and dust
remain far from the protosun

23. The planets formed with distinct orbits around the sun
The planets formed with distinct orbits around the sun. Some planets have satellites which orbit individual planets.

24. Solar Nebula Theory Is there Evidence?
The Hubble Telescope image shows a solar nebula as a protoplanetary disk or “proplyd” located in Orion Nebula with dozens of others. The proto star is the bright glow; dark area is a dense molecular cloud.
This image from the Hubble Space Telescope shows a solar nebula, evidence to support the Solar Nebula theory. This is called a protoplanetary disk, or proplyd. This proplyd lies at the heart of the Orion Nebula along with dozens of other proplyds. The darker area is the dense molecular cloud while the proto-star (a star that is hot, but not hot enough to initiate fusion) is the glow in the center.

25. This NASA image clearly shows that this star has 4 distinct rings
This NASA image clearly shows that this star has 4 distinct rings. These rings will eventually coalesce into solid bodies called planets.

26. The Planets Terrestrial Planets Jovian Planets Mercury Venus Earth
Mars
Small in size
Composed of rock
Metallic cores
Asteroid Belt
Jovian Planets
Jupiter
Saturn
Uranus
Neptune
Large in size.
Composed of hydrogen, helium, ammonia, methane
Small rocky cores
Kuiper Belt Pluto: no longer has planet status

28. Earth’s Very Early History
Started out cool about 4.6 billion years ago probably with uniform composition/density
Temperature increased. Heat sources were:
meteorite impacts
gravitational compression
radioactive decay
Heated up enough to melt iron and nickel within the newly formed Earth

29. The earth and moon were heavily bombarded in Earth’s early history.

30. Earth’s Differentiation
Differentiation = segregated into layers of differing composition and density
Early Earth was probably uniform
After heating, molten iron and nickel sank to form the core
Lighter minerals flowed up to form mantle and crust

31. Forming the Moon Impact by Mars-sized planetesimal with early Earth
4.6 to 4.4 billion years ago
Ejected a large quantity of hot material that cooled and coalesced to form the moon

32. Impact hypothesis for moon

33. Most of the lunar material
came from the mantle of the colliding planetesimal
The material cooled and
crystallized into lunar layers
Moon is smaller than Earth and cooled quickly. Light colored surface areas are lunar
Highlands – heavily cratered.
evidence of massive meteorite
Bombardment
Mare: areas of lava flows more likely due to impact than tectonics

34. Earth—Dynamic Planet Earth was also subjected
to the same meteorite barrage
that pock-marked the Moon
Why isn’t Earth’s surface also densely cratered?

35. Major elements on Earth
Top 4 most abundant elements: Oxygen Silicon aluminum

36. Earth’s Interior Layers
Lithosphere
solid upper mantle and crust -- broken into plates that move over the
asthenosphere
Asthenosphere
part of upper mantle
behaves plastically and slowly flows

37. Plate Tectonics Theory
Lithosphere is broken into individual pieces called plates
Plates move over the asthenosphere
as a result of underlying convection cells

38. Plate Tectonic Theory Movement at plate boundaries At plate boundaries
plates diverge
plates converge
plates slide sideways past each other
At plate boundaries
Volcanic activity occurs
Earthquakes occur

39. Modern Plate Map Active tectonic boundaries are in red

40. Plate Tectonic Theory
After decades of puzzling evidence, the theory was developed in the1960s
Provides a framework for
interpreting many aspects of Earth on a global scale
and relating many seemingly unrelated phenomena
Key to interpreting Earth history The “unifying theory of geology”

41. Plate Tectonics and Earth Systems
Mechanism: Plate tectonics is driven by convection in the mantle
and in turn drives mountain building
and associated igneous and metamorphic activity
Global effects of plate movement: Arrangement of continents affects
solar heating and cooling,
winds and weather systems
Rapid plate spreading and hot-spot activity
may release volcanic carbon dioxide
and affect global climate

42. History of Earth
The history of the early earth through the present is revealed mainly in the rock and fossil records.
By applying principles of formation and determining environments from life forms, early interpretations about Earth’s land masses and oceans have been made

43. Theory of Organic Evolution
Provides a framework for understanding the history of life
Darwin’s
On the Origin of Species by Means of Natural Selection, published in 1859,
revolutionized biology
Provided the mechanism of natural selection

44. Central Thesis of Evolution
All present-day organisms
are related and descended from organisms that lived during the past
Natural selection is the mechanism
that accounts for evolution
Natural selection results in the survival
to reproductive age of those organisms
best adapted to their environment

45. History of Life The fossil record provides perhaps
the most compelling evidence
in favor of evolution
Fossils are the remains or traces
of once-living organisms
Fossils demonstrate that Earth
has a history of life

46. Geologic Time From the human perspective time units are in
seconds, hours, days, years
Ancient human history
hundreds or even thousands of years
Geologic history
millions, hundreds of millions, billions of years

47. Geologic Time Scale
Resulted from the work of many 19th century geologists who
pieced together information
from numerous rock exposures,
constructed a sequential chronology
based on changes in Earth’s biota through time
The time scale was subsequently dated in years
using radiometric dating techniques

48. Uniformitarianism: The Present is the key to the past
Uniformitarianism is a cornerstone of geology
is based on the premise that present-day processes
have operated throughout geologic time
The physical and chemical laws of nature
have remained the same through time