Transcript File - Vagabond Geology

Senior University
January 25 to March1 2010
Vagabonds tramping through Geology
Africa
“It is the supreme art of the teacher to awaken
joy in creative expression and knowledge”
Albert Einstein
Grab your mental climbing gear and
let’s scale the heights of Africa
Tramping
through the
Stone
Senior University
Field
Trip
and Iron Ages in Central Texas
March 9, 2010
Objective of this course: to show how geology
shaped human history, e.g. in Africa
Geologic Map: Africa
Suggested Geological References
Physical Geology, Judson & Kauffman,1990
Evolution of the Earth, Prothero & Dott, 2002
The focus of our study the geology
of Africa
Geological maps
show different rocks at the
surface
if soils
and vegetation
removed
Management
Disclosure:
The impact ofwere
geology
on
shaping human history is not discussed in any
geology textbook or in any scientific literature YET
Where we’ll be studying the geology
of Africa
Geologic Map: Africa
Congo River &
Major Undiscovered
Oil and Gas
East African
Rift Valleys &
the Advent
of Humans
What supports
Rift Extension & the proposition
River Modification
that geology
human history?
Creatingshapes
Awesome
Scenic Wonders
Support for the Proposition
that Geology Shapes Human History
Four Awesome Scientific Discoveries
in the last 50 years defining the
Earth’s Rocky Crust
First: . Continental (crustal plate) Drift
1. Continental (crustal plate) Drift
2. Plate Tectonics
3. Paleo-magnetics
4. Absolute Age Dating
Four Discoveries of the last 50 Years
That Define the Earth’s Rocky Crust
1.Continental (crustal plate) Drift
The slow movement of the crustal plates
over the face of the earth
Crustal Plates: Both Oceanic & Continental
Crustal Plates: Both Oceanic & Continental
Indian plate under Asian plate = mountain building
Combination
Oceanic
Combination
Combination
Combination
Continents are carried on their crustal plate
Present Day
Continental Drift:
Last 250 million years
How has continental drift shaped
human history?
250 million years ago
http://schools.techno.ru/sch518/koridor/geograf
/detrab/Tektonika/litosfera2.htm
How has continental drift shaped
human history?
Western
Hemisphere
Eastern
Hemisphere
And
Created the Western and Eastern Hemispheres
Critical to the migration of humans out of Africa
How has continental drift shaped
human history?
And
Why is elongation important?
Shaped the
It determines
the continents
number of climate
Three
elongated
north-south
zones
that
the
continent
covers
One elongated east-west
How has continental drift shaped
human history?
Why is that important?
Tropical climate zones
Note
that Africa
and South
In addition
to continental
drift,America
what was
Because
nolocated
world
power
discovered
about
geology
ofever
the
are
not
well
for
thehas
creation
Positioned
thethe
continents
Tropics!!!
earth’s
rocky
crust
inthe
the
last 50zones
years?
of
a world
power
withdeveloped
respect
toin
the
climate
Four Discoveries of the last 50 Years
that Define the Earth’s Rocky Crust
The deforming
of
earth’s
crust
1. Continental Drift
when continents (plates)collide
2. Plate Tectonics
Two important types of deformation:
1. mountain building
2. broad warping of the continental crust
Plate Tectonics: aka mountain building
Collision: oceanic with continental plate
Collision Mountains
North American continental
plate over riding the
Pacific oceanic plate
Next: Two continental plates collide
Collision Mountains
Plate Tectonics:
Collision of two continents
Why are mountain
important?
Next: Plateranges
Tectonics
Natural
resources
arefaulting
concentrated
Uplift
and rift
in
and aalong
mountainhotspot
ranges
over
sub-crustal
Plate Tectonics: Uplift and rift faulting
over a sub-crustal hotspot
Central Africa:
Up-lifted
Faulted
Rift Valleys formed
& Volcanoes
Why
thisTectonics:
event important?
Next,was
Plate
Broad warping
This
geologicalcrust
eventproduces
of unique
the continental
coincided
with
the
advent
of
major river drainage systems
the human race!
Eastern Hemisphere: Major Rivers Produced by
the Broad Warping of the Continental Crust
Eurasia
Africa
The Tropics
Major rivers
The
Third
Discoveryin
ofmajor
the last
50 flood
Years
All
early
civilizations
river
that Define
the Earth’s
Rocky Crust
plains
in the Northern
Temperate
Zone!
Four Discoveries of the last 50 Years
that Define the Earth’s Rocky Crust
1. Continental Drift
Paleo-magnetics defines the lat-long
Plate Tectonics
of a rock 2.when
it is formed
3. Paleo-magnetics
All our continental drift reconstruction
What
fourth
discovery?
maps is
arethe
based
on Paleo-magnetics
Four Discoveries of the last 50 Years
that Define the Earth’s Rocky Crust
Again, all our continental drift maps are
heavily dependent on Absolute Ages
4. Absolute Age Dating
Absolute Age Dating uses the decay of
Now, four geological processes
radio active minerals to determine the
that shaped
age ofhuman
a rock history
Now four geological processes
that shaped human history
1. Continental Drift
2. Plate Tectonics
3. Weathering
4. Erosion
Four Geologic Processes that
shaped Human History
Continental Drift
Weathering: Natural destruction of
the rockyPlate
continental
crust
Tectonics
Weathering
Weathering produces
soils
of
different
Erosion
Finally,
Erosion
fertilities depending on the rock type
Four Geologic Processes that
shaped
Human History
Erosion:
Continental Drift
Natural process
of moving
Tectonicsthe oceans
rock debrisPlate
toward
Weathering
What Natural
Resources
Erosion
define
Human
History?
Erosion
Produces:
Topography
River flood plains
Rock outcrops with natural resources
Rock outcrops
Proposition:
& natural resources:
Resources
Shaping these
Human
History
Lands controlling
natural
resources become major nations
Iron, Coal, Petroleum, & Uranium
Iron, Coal, & Oil
Iron
and
Coal
Here’s
how
natural
resources
Iron
shaped
historic
Copper,
Tin,
Arsenic,time
Zinc
Copper
Flint and Obsidian
What Natural Resources define Human History?
Geologic Division of Historic Time
Iron,Iron,
Coal,
Oil & Uranium
Coal, Petroleum,
& Uranium Age
Oil
Iron, Coal, & Oil Age
Iron & Coal Age 2
Iron & Coal: Industrial Age
Iron & Coal: Renaissance
1950 to Present
1900 to 1950 AD
1830 to 1900 AD
1700 to 1830 AD
Next: Five Geologic Events
Shaped
1450that
to 1700
AD
Iron Iron & Coal:
Middle Ages
Human
History470 to 1450 AD
&
Coal
Copper, tin,
arsenic, & zinc
Flint & Obsidian
Iron Age 2 Rome
Iron Age 1 Greece
Bronze Age
to 470 AD
750 BCE
1400 to 750 BCE
3300 to 1400 BCE
Copper Age
3300 to 3000 BCE
Stone Age (end of Ice Age) 70,000 to 3300 BCE
Five Geologic Events that Shaped
Human History
1. Continental Drift shapes &
positions the continents
Migration path of humans
created
How has continental drift shaped
human history?
Eastern
Western
Hemisphere
Hemisphere
The second history shaping event
Created the Western and Eastern Hemispheres
Critical to the migration of humans out of Africa
Five Geologic Events that Shaped
Human History
1.
Continental Drift shapes & positions the continents
Migration path of humans created
2. Continental Drift & Plate Tectonics:
Africa drifts into Europe = Alps
India collides with Asia = Himalayas
Optimum farming environment
created in six major river
flood plains.
Geological Event # 2: 6000 mile mountain
range created by Africa & India colliding
with Eurasia
Yellow
Yangtze
Nile
Tigris
Euphrates
Indus
Ganges
Event #3. Plate Tectonics: East Africa uplifted,
rift faulted with advent of human beings
Ideal trend for the early development
of large scale farming civilizations
Five Geologic Events that Shaped
Human History
1.
2.
Continental Drift shapes & positions the continents
Migration path of humans created
Continental Drift & Plate Tectonics:
Africa drifts into Europe = Alps
India collides with Asia = Himalayas
Optimum farming environment created
3. Plate Tectonics: East Africa uplifted,
rift faulted with advent of human beings
3. Plate Tectonics: East Africa uplifted,
rift faulted with advent of human beings
Eastern Africa:
Up-lifted
Faulted
Location of oldest
human fossils
Rift Valleys formed
& Volcanoes
Event # 4. Weathering exposes critical
ores andPlate
oil atTectonics:
or near the earth’s surface:
Uplift and rift faulting
over a sub-crustal hotspot
Five Geologic Events that Shaped
Human History
1.
Continental Drift shapes & positions the continents
Migration path of humans created
2.
Continental Drift & Plate Tectonics:
Africa drifts into Europe = Alps
India collides with Asia = Himalayas
Optimum farming environment created
3. Plate Tectonics: East Africa uplifted,
rift faulted with advent of human beings
4. Weathering exposes critical ores and
oil at or near the earth’s surface:
Example: Natural Resources of Africa
Natural Resources that shaped World History
Iron Age
Africa
Iron
Coal
Natural Resources that shaped World History
Africa today
Natural Resources
Copper
Tin
Iron
Coal
Oil
Very large
deep water
oil reserves
Natural Resources that shaped World History
Major Rivers
Nile
Niger
Congo
Copper
Tin
Iron
Coal
Oil
Event
#
Very large
deep water
oil reserves
\
5. Continental Glaciation prevents early
farming civilizations in the northern half
of the Northern Temperate Zone
Five Geologic Events that Shaped
Human History
1.
Continental Drift shapes & positions the continents
Migration path of humans created
2.
Continental Drift & Plate Tectonics:
Africa drifts into Europe = Alps
India collides with Asia = Himalayas
Optimum farming environment created
3. Plate Tectonics: East Africa uplifted,
rift faulted with advent of human beings
4. Weathering exposes critical ores and
oil at or near the earth’s surface:
Example: Natural Resources of Africa
Event # 5. Continental Glaciation prevents early
farming civilizations in the northern half
of the Northern Temperate Zone
Yellow
Yangtze
Nile
Tigris
Euphrates
Indus
Ganges
Next Week:
Africa and the Major Nations of
the World
World Empires: last 7000 years
Stone Age
Hunters & Gatherers
Families, clans,
& tribes
Sticks and stones
3500
3000
Copper Age
4500
2500
Bronze Age:
World
1500
Iron Age
Iron & coal Age
Farming
Flood plain empires Hill country empires
Iron & steel tools &
Bronze tools
weapons
weapons
Iron, coal, oil Age
Archeological Ages
Geologic Division of Historic Time
Iron, Coal, Oil & Uranium
Iron, Coal, Petroleum, & Uranium Age 1950 to Present
Iron, Coal, & Oil Age
1900 to 1950 AD
Iron & Coal Age 2
1830 to 1900 AD
Iron & Coal: Industrial Age
1700 to 1830 AD
Iron & Coal: Renaissance
1450 to 1700 AD
Iron & Coal: Middle Ages
470 to 1450 AD
Iron Age 2 Rome
to 470 AD
750 BCE
Iron Age 1 Greece
1400 to 750 BCE
Bronze Age
3300 to 1400 BCE
Copper, tin,
Iron
How does the history of Africa
& fit in with world history?
Coal
arsenic, & zinc
Flint & Obsidian
Copper Age
3300 to 3000 BCE
Stone Age (end of Ice Age) 70,000 to 3300 BCE
Nations of World History
Left half of chart: 5000 BC to 1400 BC: pre-Iron Age
Right half of chart: 1400 BC to present time
Let’s look at nations
in the pre-Iron Age
Stone Age
4500
4000
3500
3000
2500
1500
Bronze Age:
Copper Age
5000
Africa
Ancient Times: 5000 BC to 1000 BC
Sumeria
Mature Indus
Xia Yellow River
Iron age
Egypt: Nile
Where were these nations located?
World’s Earliest Civilizations:
pre-Iron Age
Egypt
Nile River
Sumeria
Tigris &
Euphrates
Xia Dynasty
Yellow River
Now, nations in the
early
Iron
Age
Ganges
Yangzi River
Mature
Indus River
From: Hammond Atlas, 1972
All are in major river flood plains!
Rome
Greece
Iron & Coal age
Let’s look at Africa
Islamic States
Iron, Coal & Oil age
Iron age
Iron Age Nations & Empires Worldwide
Nations of (in) Africa
Mediterranean Africa
Egyptian Kingdoms
Greece
Rome
Islamic States
Central & Southern Africa
Where is Kush?
Ancient Egypt
Nile River
Kush
Kush aka Nubia
Why is Kush where it is?
http://geology.com/world/africa-physical-map.shtml
The basis of
Kush economy
Egypt: Natural Resources
Nations of Africa (excluding Egypt)
Where is Axum?
Kingdom of Axum aka Aksum
Nile
River
Kush
Axum
Ethiopia
Kingdom of Axum aka Aksum
White
Nile River
Now, the last of the African nations
White
Nile River
A trading nation between
Ethiopia, Egypt, & Arabia
Nations of Africa (excluding Egypt)
Niger
River
http://exploringafrica.matrix.msu.edu/students/curriculum/m7a/activity3.php
Ghana
Traded in gold, iron, and salt
Summary: There have been no major
African nations since ancient Egypt!
Why?
How Geology shaped human history
Four geologic processes
Five geologic events
Four Geologic Processes that
shaped Human History
Continental Drift
Plate Tectonics
Weathering
Erosion
Four Geologic Processes that
shaped Human History
Continental Drift
Plate Tectonics
The slow movement
of the continents
over the face of the earth
Weathering
Erosion
Present Day
Continental Drift:
Last 250 million years
250 million years ago
http://schools.techno.ru/sch518/koridor/geograf
/detrab/Tektonika/litosfera2.htm
Continental Drift Created two Hemispheres
Western
Hemisphere
Eastern
Hemisphere
Continental Drift Shaped the Continents
Significance of Position & Shape
Northern Temperate Climate Zone:
Historically ideal for major civilizations
Tropical Climate Zones:
Historically unfavorable for major civilizations
Eastern Hemisphere: Major Rivers & Mountains
Eurasia
Africa
The Tropics
Major mountains
Major rivers
All early civilizations in major flood plains
in the Northern Temperate Zone!
Four Geologic Processes that
shaped Human History
The deforming
of earth’s crust
Continental Drift
when continents collide
Plate Tectonics
Weathering
Two important types of deformation:
1. mountain building
2. broad warpingErosion
of the continental crust
The Earth’s Rocky Crust (aka skin)
Continental
Crust
Oceanic
Crust
The earth’s skin, aka crust, is broken into many plates,
both large and small
http://pubs.usgs.gov/gip/dynamic/inside.html
Crustal Plates: Both Oceanic & Continental
Indian plate under Asian plate = mountain building
Combination
Oceanic
Combination
Combination
Plate boundaries are sites for
earthquakes and volcanoes
Combination
Crustal Plate Boundaries & Earthquakes
Earliest Major Civilizations in
flood
plains
of major rivers draining
Two types
of crust:
(under zones
the deep(mountains)
oceans)
highoceanic
earthquake
continental (the continents)
Two types of Crust:
1. Continental crust
2. Oceanic crust
Cross Section: Two types of Crust
Oceanic Crust
Continental Crust
5 miles thick
20 to 50 miles thick
Plate tectonics:
deformation when two or more plates collide
Plate Tectonics: aka mountain building.
Collision: oceanic with continental crust
New Mountains
Oceanic Crust
5 miles thick
Continental Crust
20 to 50 miles thick
Plate Tectonics: aka mountain building
Collision of two continents
Africa
Europe
New Mountains
Mountain Building: collision of
an oceanic & a continental plate
Plate Tectonics: aka mountain building
Collision: oceanic with continental plate
Collision Mountains
North American continental
plate over riding the
Pacific oceanic plate
Next: Two continental plates collide
Collision Mountains
Plate Tectonics:
Collision of two continents
Plate Tectonics:
Uplift and rift faulting
over a sub-crustal hotspot
Central Africa:
Up-lifted
Faulted
Rift Valleys formed
& Volcanoes
Plate Tectonics:
Uplift and rift faulting
over a sub-crustal hotspot
Block Diagram of a Rift Valley
Rift Valley
Central Africa:
Equatorial How thick is
High elevation
a
continent?
Rift environments
Volcanic
Uplift
http://www.tiscali.co.uk/reference/encyclopae
dia/hutchinson/image_preview.html?image
How thick is
A continent?
8000 miles
4000 miles = radius
How thick is
A continent?
2000 miles
How thick is
A continent?
1000 miles
How thick is
A continent?
500 miles
How thick is
A continent?
100 miles thick
500
1000
2000
4000
8000
How thick is
A continent?
100 miles thick
A continent is 25 to 50 miles thick!
How far does
Africa
extend?
North
Pole
North Africa
Center of
the earth
Equator
West
African Continent
Now the third geological process:
weathering
South Africa
South
Pole
Four Geologic Processes that
shaped Human History
Continental Drift
Weathering: Natural destruction of
the rockyPlate
continental
crust
Tectonics
Weathering
Erosion
Weathering: Natural destruction of
the rocky continental crust
Causes:
sun
rain
plants
wind
Products:
rock debris
soils
WEATHERING: Destroys Rocks
Creates:
1. soils (+ decaying plants)
2. rock debris
Produces: unique environments
Rock “Debris”
1. quartz sand
2. muds (clays)
3. calcium carbonate solutions
All three carried away by erosion,
the fourth process that shaped history
Four Geologic Processes that
shaped Human History
Continental Drift
Erosion:
Plate Tectonicsof moving
Natural process
rock debris toward the oceans
Weathering
Erosion
Erosion: Natural process of moving
rock debris to the oceans
at the continental margins
Products:
topographies
rock outcrops
river flood plains
geosynclines
Erosion:
Moving the weathered rock debris to the sea by:
1. gravity!!! It all goes down hill
2. water:
brooks
streams
rivers
Erosion:
1. produces topography
2. creates river flood plains
3. created geosynclines
4. exposes different rocks at the earth’s surface
The erosional topography of Africa
The Erosional Topography of Africa
Nile River
Basin
Mountains
Niger River
Basin
Congo River
Basin
Highlands
http://geology.com/world/africa-physical-map.shtml
Mountains &
Volcanoes
Erosion: Natural process of moving
rock debris to the oceans
at the continental margins
Products:
topographies
river flood plains
creates geosynclines
Cross section: Typical Geosyncline
land
ocean
river debris
Geosynclines are sites for the
generation of oil and gas
Nile, Congo, or Niger river geosyncline
Erosion:
Moving the weathered rock debris to the sea by:
1. gravity!!! It all goes down hill
2. water:
brooks
streams
rivers
Erosion:
1. produces topography
2. creates river flood plains
3. Creates geosynclines
4. exposes different rocks
at the earth’s surface
The surface rock outcrops of Africa
Rocks of the earth’s crust exposed
at the surface in Africa by erosion
Each color represents a different rock at the surface
Weathering & erosion of each rock produces unique:
1. soils
2. topographies
3. outcrops
A. flint, obsidian,
B. copper & tin,
C. iron & coal
Proposition: These “outcrop” materials
helped to shape human history!
USGS Geological Map: Africa
Natural Resources that Shaped World History
Bronze Age
Africa
Copper
Tin
Iron
Coal
Oil
World’s greatest
concentration
of Cu and Sn!
Tropics
World’s greatest
concentration
of Cu and Sn!
No Bronze Age nations here; why?
Obviously we need more than Cu & Sn!
Remember
Significance of Position & Shape
Northern Temperate Climate Zone:
Historically ideal for major civilizations
Tropical Climate Zones:
Historically unfavorable for major civilizations
Natural Resources that shaped World History
Iron Age
Africa
Iron
Coal
Natural Resources that shaped World History
Iron Age
Africa
Egypt
Africa’s only
major nation
Iron
Coal
Apparently
Tropicseven in the Temperate
Zone we need more than Fe & Coal
Why no major
nations here
and here
Natural Resources that shaped World History
Africa today
Natural Resources
How did four geologic processes
account for the history of Africa?
Copper
Tin
Iron
Coal
Oil
Very large
deep water
oil reserves
Natural Resources that shaped World History
Major Rivers
Nile
Niger
Congo
How did five geologic events
account for the history of Africa?
Copper
Tin
Iron
Coal
Oil
Very large
deep water
oil reserves
\
How Geology shaped human history
Next week,
Five geologic events
that shaped human history
\
http://commons.wikimedia.org/wiki/File:Africa_topography_map_with_borders.png
http://en.wikipedia.org/wiki/File:CongoLualab
a_watershed_plain_political.png
http://pubs.usgs.gov/of/1997/ofr-97-470/OF97-470A/AFRICA.pdf
http://pubs.usgs.gov/of/1997/ofr-97470/OF97-470A/AFRICA.pdf