historical geology origins
TRANSCRIPT
-
7/30/2019 Historical Geology Origins
1/33
1
HISTORICAL GEOLOGYHISTORICAL GEOLOGY
Earth is a Dynamic andEarth is a Dynamic and
Evolving PlanetEvolving Planet
Changes in its surface
Changes in life
-
7/30/2019 Historical Geology Origins
2/33
2
Historical GeologyHistorical Geology
The study of the origin and evolution of the earthand life.
Placing events in order
Explaining how and why events took place
Plate Tectonics: Earths outermost part is composed of aseries of moving plates whose interactions have affected the
planets physical and biological history.
Organic Evolution
Geologic Time
PLATE TECTONICS
-
7/30/2019 Historical Geology Origins
3/33
3
Historical GeologyHistorical Geology
The study of the origin and evolution of theearth and life. Placing events in order
Explaining how and why events took place Plate Tectonics
Organic Evolution: Earths biota has evolved orchanged throughout its history.
Geologic Time
ORGANIC EVOLUTION
-
7/30/2019 Historical Geology Origins
4/33
4
Historical GeologyHistorical Geology
The study of the origin and evolution of the earthand life.
Placing events in order
Explaining how and why events took place
Plate Tectonics
Organic Evolution
Geologic Time: The physical and biological changes that
have occurred on Earth have done so over very long periodsof time.
-
7/30/2019 Historical Geology Origins
5/33
5
Historical GeologyHistorical Geology
The study of the origin and evolution of theearth and life. Placing events in order
Explaining how and why events took place Plate Tectonics
Organic Evolution
Geologic Time
In all cases, principles and theories ofHistorical Geology are derived from datagathered by Scientific Method
GeologyGeology Study of the Earth
Earth as a system and subsystems p.3 fig. 1.1
Atmosphere
Hydrosphere
Biosphere
Lithosphere (plates)
Mantle
Core
-
7/30/2019 Historical Geology Origins
6/33
6
AtmosphereAtmosphere
HydrosphereHydrosphere
-
7/30/2019 Historical Geology Origins
7/33
7
BiosphereBiosphere
Lithosphere, Mantle, CoreLithosphere, Mantle, Core
-
7/30/2019 Historical Geology Origins
8/33
8
Fig. 1-1, p. 3
-
7/30/2019 Historical Geology Origins
9/33
9
What is Geology ?What is Geology ?
Physical Geology
Earth materials
Physical processes
Historical Geology
Earth materials and processes
Origin and evolution of Earth
Origin and evolution of Life
Earth Materials and ProcessesEarth Materials and Processes Minerals and Rocks
Processes such as weathering,sedimentation, lithification, uplift/orogeny,folding and faulting, formation ofunconformities
-
7/30/2019 Historical Geology Origins
10/33
10
Historical GeologyHistorical Geology
In historical geology we study changes in our dynamic planet
how and why past events happened
implication for todays global ecosystems
Principles of historical geology not only aid in interpreting Earths history
but also have practical applications
William Smith, an Englishsurveyor/engineer used his study of rock sequences and fossils
to predict the kinds and thicknesses of rocks
to be excavated in the construction of canals
ORIGINSORIGINS
-
7/30/2019 Historical Geology Origins
11/33
11
UNIVERSE FORMS13.7 Billion Years Ago
THE BIG BANG
How Do We Know?How Do We Know? The Doppler Effect
-
7/30/2019 Historical Geology Origins
12/33
12
RedshiftRedshift
Absorption lines in the optical spectrum of asupercluster of distant galaxies (right), ascompared to absorption lines in the opticalspectrum of the Sun (left). Arrows indicateredshift. Wavelength increases up towardsthe red and beyond (frequency decreases )
The Red ShiftThe Red Shift Observed by Edwin Hubble in 1929, the
optical spectra ( and red shift) of distantgalaxies indicated that galaxies weremoving away from Earth and the moredistant galaxies were moving faster. TheUniverse is expanding.
-
7/30/2019 Historical Geology Origins
13/33
13
Expanding UniverseExpanding Universe
Raisin Bread Analogy
Big Bang TheoryBig Bang Theory
Evidence for the Big Bang The redshift indicates that the universe is
expanding. Expansion suggests an origin at a single point.
Rate of expansion indicates explosion at 13.7billion years ago
Everywhere is a background radiation of 2.7 Kabove absolute zero, thought to haveoriginated with the big bang.
-
7/30/2019 Historical Geology Origins
14/33
14
Cosmic Microwave BackgroundPhotons from the earliest days of the universe
Background RadiationBackground Radiation Discovered by Arno Penzias and Robert
Wilson of Bell Telephone Laboratories
A pervasive microwave radiationeverywhere in the Universe measured as2.7 Kelvin above absolute zero.
Thought to be the gradually fading
radiation (photons) from the Big Bang; anafterglow.
-
7/30/2019 Historical Geology Origins
15/33
15
Big Bang TheoryBig Bang Theory
Cosmologists do not know the nature of theuniverse at time zero of the Big Bang.
Big Bang occurred
Forces followed in the first second Gravity (attraction of bodies)
Electromagnetic Force (electricity and magnetism;holds atoms in molecules)
Strong Nuclear Force (binds protons and neutrons
together) Weak Nuclear Force (force that causes radioactive
decay)
-
7/30/2019 Historical Geology Origins
16/33
16
Big Bang TheoryBig Bang Theory
At 300,000 years: Hydrogen, Helium, Light
Next 200 million years stars and galaxies,chemicals (denser elements) from thedeath of stars
GALAXIES FORM12.7 Billion Years Ago
-
7/30/2019 Historical Geology Origins
17/33
17
12.7 Billion Years AgoFirst Stars and Galaxies
Origin of the Solar SystemOrigin of the Solar System Solar Nebula Theory
Solar system formed from collapse of a hugemolecular cloud, a nebula, about 4.6 billionyears ago.
90% of material condensed into the center ofa counterclockwise rotating disk, forming thesun.
Planetesimals formed from collisionseventually forming planets
-
7/30/2019 Historical Geology Origins
18/33
18
Interstellar Material
The most accepted
theory of the origin ofstars and planetary
systems is the collapse
of interstellar gas and
dust.
Our understanding of the solar
nebular theory is that planets
form as a by-product of starformation.
1. If the nebula is compressed
(overcoming the gas pressure),
then gravity may take over and
the nebula will collapse inward.
2. As nebular particles come
closer together, the gravitational
attraction increases (remember
the law of gravitation). The
increased attraction and collapseresults in an increase in
temperature. As the cloud
collapses, it begins to slowly
rotate and flatten into a disk.
-
7/30/2019 Historical Geology Origins
19/33
19
. There are several observations
about the solar system that are
evidence in favor of the Solar
Nebula Theory.
1. All of the planets revolve
around the Sun in the same plane
(planetary plane).
2. The Suns rotational equator
lies roughly in the planetary
plane.
3. All of the planets revolve around the Sun in the same direction.4. Planet orbits are nearly circular.
Planets,includingEARTH
finish accretingfrom asteroids 4.6 BILLIONYEARS AGO
-
7/30/2019 Historical Geology Origins
20/33
20
Formation of PlanetsFormation of Planets
Inner terrestrial planets formed in highheat and solar winds blew away gases.
Outer Jovian planets formed with innercore of solids and are composed of gasesthat condense at low temperatures
Asteroid belt
Comets
The Hoba Meteorite, in Namibia
-
7/30/2019 Historical Geology Origins
21/33
21
Photo by Howard Edin, American Meteor Society
-
7/30/2019 Historical Geology Origins
22/33
22
COMETS
-
7/30/2019 Historical Geology Origins
23/33
23
-
7/30/2019 Historical Geology Origins
24/33
24
MOHO
-
7/30/2019 Historical Geology Origins
25/33
25
Earth as a Dynamic SystemEarth as a Dynamic System
Division into layers results from variationsin
Density (Core=10-13 g/cm3; crust 2.7 g/cm3)
Composition (Fe,Ni; Fe,Mg; Si,Al)
Temperature
Pressure
16 g/cc SOLIDFe, Ni (S, Si)1300 kmInner core
11 g/cc LIQUIDFe, Ni (S, Si)2200 kmOuter core
4.5 g/cc SOLIDMg, Fe, Si, O2900 kmMantle
2.7 g/cc SOLIDSi, O, Al = Granite30-50 kmContinentalcrust
2.9 g/cc SOLIDSi, O, Fe, Mg, Al
= Basalt
3-10 kmOceanic
crust
State/DensityCompositionThicknessLayers
Overlaid layers:
Plastic (flows),but SOLID
Portion ofmantle
100-350 kmAsthenosphere
RIGID, SOLID,
BRITTLE:breaks intoplates
100% Crust +
Upper Mantle
100-200 kmLithosphere
-
7/30/2019 Historical Geology Origins
26/33
26
EarthEarths Cores Core Divided into two parts
Inner solid
Outer liquid
-
7/30/2019 Historical Geology Origins
27/33
27
EarthEarths Mantles Mantle
Divided into ThreeParts
Solid lower mantle
Asthenosphere mushybehaves plastically andgenerates magma
Upper mantle is solid
and with the crustconstitutes thelithosphere
MOHO
-
7/30/2019 Historical Geology Origins
28/33
28
EarthEarths crusts crust
Divided into two types
Continental crust (thicker, more Si rich rocks)
Oceanic crust (thinner, more mafic)
-
7/30/2019 Historical Geology Origins
29/33
-
7/30/2019 Historical Geology Origins
30/33
30
LithosphericLithospheric PlatesPlates
Theory of Plate Tectonics
Plate tectonics and earth systems (p.11,fig.1.2
-
7/30/2019 Historical Geology Origins
31/33
31
Organic Evolution and the HistoryOrganic Evolution and the History
of Lifeof Life Theory of organic evolution provides
framework for study of history of life.
Integrated with and consistent with PlateTectonic theory
Organic Evolution and the HistoryOrganic Evolution and the History
of Lifeof Life
Fossils
As evidence of organic evolution
As evidence of history of life
As evidence of earth history (Plate Tectonics)
Mesosaur
-
7/30/2019 Historical Geology Origins
32/33
32
Geologic TimeGeologic Time
Immensity of Geologic time is hard tocomprehend
Time Scale stems from early need todivide Geologic Time into units.
Advantages of the Time Scale
Sedimentary Rocks and fossils
More refined units
Time ScaleTime Scale
-
7/30/2019 Historical Geology Origins
33/33
UniformitarianismUniformitarianism James Huttons insight into processes and time
Catastrophism and catastrophic events
Rates and Intensities vary in geologic history
Uniformitarianism Present is the key to thepastLaws of nature have not changed withtime.Processes changing and shaping earthare basically the same as in the past.Given
enough time, present day processes account forwhat we see in the rock record.