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Tramping Geology through the Appalachians
Original music by Bob Blackshear:
Nashville recording artist
Song writer and singer
Sun City Resident
Vagabonds & Sojourners Tramping Geology:
The Appalachian Mountains
Session 1: Getting Started
An Overview of the Next 6 Weeks
Remember our field trip, Nov. 3rd
And now, Geology in the News
Geology in the News
Next, diamonds reveal geology of the
deep “earth furnace” that generates
many of our natural metallic resources
New York Times, Sept.15, 2011
Geology in the News
Continent
Oceanic crust
And, China turns out our “green”
lights, at least for a while
New York Times, Sept.16, 2011
Mantle plume
(hot spot)
Geology in the News
Now to “playing in the sand pile” in
McCulloch County, Texas
New YorkAustin
Times,
Sept.16,statesman,
2011
American
9-18-11
Geology in the News
McCullough
County
Austin
Up close
McCullough
County
Sand quarries
McCulloch County
The big picture: why sand here?
Is the favorable sand elsewhere?
North America 505 million years ago
Ancient beach sands
McCullough
County
Now to an earthquake in Himalayas
Geology in the News
Tibet-China
6.9
India
Geology in the News
Geology in the News
Nile geosyncline
gas prone
Geology in the News
Cyprus Offshore territory
Nile geosyncline
gas prone
Back to the Western Hemisphere
Expensive production from deep water (6,000 feet+) Brazil and
Canadian tar sands forecast to provide oil to replace diminishing
resources in Mexico and Venezuela.
Geology in the News
Computer modeling of oil & gas
reservoirs using seismic, drilling,
production, and conceptual data
Now, back to the Appalachians
Vagabonds & Sojourners in the Appalachians
Six Sessions
As we follow the Great Valley we’ll:
1. explore the heart of the Appalachians
2. note to economic resources of the interior
3. relate human history to the last great continental glacier
Return to NC & follow
the Great Valley through
VA, WV, MD, PA, NY, CT, &
VT into Canada
Where are the lands of the Sojourners?
Follow the Blue
Ridge to Georgia
& Alabama
Begin in
North Carolina
Blue Ridge Mts
The Lands of the Sojourners
5
1
0
14
3
1
4
14
Sandi’s first
4
geology field trip:
Wisconsin Dells age 6 months
2
Back to Session 1
11 7 5
17
Vagabonds & Sojourners Tramping Geology:
The Appalachian Mountains
Session 1: Getting Started
What is a geologic mountain?
What is a geologic mountain?
Rocks deformed by the collision of
two plates of the earth’s crust
Mountains grow to great heights & are
gradually destroyed by weathering & erosion
Mountain Classification
Youthful Mountains: Washington State
Mature Mountains:
Mount Mitchell, North Carolina
Old Age Mountains: Granville Range
Llano County, Texas
What is a geologic mountain?
Rocks deformed by the collision of
two plates of the earth’s crust
Mountains grow to great heights & are
gradually destroyed by weathering & erosion
Mountains are composed of folded,
faulted, and melted rocks
Folds, faults, and melted rocks
Valley & Ridge
Appalachian Geologic Province
Folded & faulted rock layers
What is a geologic mountain?
Rocks deformed by the collision of
two plates of the earth’s crust
Mountains grow to great heights & are
gradually destroyed by weathering & erosion
Mountains are composed of folded,
faulted, and melted rocks
Mountain building exposes different
rock types at the surface
Folds, faults, and melted rocks
Valley & Ridge
Folded & faulted rock layers
What type of rocks
do we have in the
Valley & Ridge Province?
A Land of Long Ridges and Valleys
What made the ridges & valleys?
Sedimentary rocks of all kinds
What made the valleys & ridges?
Sandstones, Limestones, & Shales:
rocks
of the
Valley
& Ridgedeposited
Province
rocks
made
from
sediments
in the oceans along continental margins
Sediments
Rocks
Sediments accumulate in oceans
at continental margins
They accumulate in layers,
one on top of another
They are composed of:
sand, mud, &/or sea shells
How do these sediments become rocks?
Creating the Three Sedimentary Rock Types
Limestones: made from sea shells
Sandstones: made from “ beach” sands
Shales: made from mud and silt
A Simple Example
37
Cross Section showing different
Sediment layers
Shell layer
Mud layer
Sand layer
How do these soft sediments
become solid rocks?
Let’s follow one shell layer as it becomes a limestone
How are Solid Rocks Formed?
Example: Limestones in Williamson County
Edwards started out as a “shell” layer 400 feet thick
What happened next?
39
Layer after layer of sediment deposited
on top of Edwards “shell” layer
Burial, compaction and dewatering.
40
What happens to newly formed rocks?
41
What did we find east of the Valley & Ridge Province?
Uplift brings to the surface
natural resources created at
great depth: e.g. metals, coal, oil, etc
Deeply buried Edwards Limestone layer
Uplifted, Weathered, and Eroded
42
What type of rocks do we find in these mountains?
The Blue Ridge Mountains
What type of rocks do we find in the Blue Ridge Mountains?
Metamorphic Rocks:
sedimentary rocks buried to great depth,
squeezed , crushed, & partially melted
Parallel
to
&
east
of
the
Blue
Ridge
Origin of metamorphic rock types:
is the sandstone
Piedmont= geological
province
quartzite
limestone = marble
shale = slate
sandstone + shale = schist = gneiss**
** most common metamorphic rocks
rocks of the Blue Ridge Mountains
Geologic Provinces of North Carolina
Great Smoky Mountains
600 million year old sandstones & shales
The Piedmont geologic province
Igneous & metamorphic rocks
What is an igneous rock?
What is an igneous rock?
Remember that Metamorphic Rocks are:
sedimentary rocks buried to great depth,
squeezed , crushed, & partially melted
Origin of metamorphic rocks:
sandstone = quartzite
basalt
shale = slate
limestone = marble
granite
An igneous rock one formed by complete
Where
we find
rocks?
meltingdo
& cooling
of aigneous
pre-existing
rock
Let’s
at the
big rocks:
picture
Two look
principle
igneous
granites-rhyolites & basalts-gabbros
The Solid Earth
Rocky
Crust
Plastic Rocky
Upper Mantle
Focus on the rocky crust
The Earth’s Rocky Crust:
Two Types
Oceanic Crust: 5 miles thick
under the oceans: basalt
Continental Crust: 20 to 50 miles thick
makes the continents: granite
Let’s look at the Oceanic Crust
The Mantle:
“Molten” (plastic) rock below the crusts
The Earth’s Oceanic Crust
The Rocky top of the Mantle
Ocean
Oceanic Crust: basalt 5 miles thick
A world view
Oceanic
OceanicCrust:
Crust:
dark
dark
colored
colored
rocks
rocks
dense
dense
rocky
mantlebasalt
rocky
toptop
of of
thethe
mantle:
All the dark blue
are basalt
All the dark blue
are basalt
Next the Continental Crust
The Earth’s Continental Crust
“Floating” on the Mantle
Oceanic Crust
Continental Crust
A world view
Continental Crust:
light colored rocks
less dense than oceanic crust
“floats” on the mantle: granite
How “thick” is North America compared
to the whole earth?
Our Earth
Radius = 4000 miles
Interior of Our Earth
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
Just one half to one quarter as thick as this orange line
4000
8000
How
far does
North
extend?
A continent
is only
25America
to 50 miles
thick!
How far does North
America
extend?
North
Pole
Cut the earth
North America
in half through
the poles
Center of
the earth
Equator
Conclusion: continents are a thin
West
veneer on the surface of our earth
Yetearth’s
theyrocky
move
“plates”
overmajor
The
crustas
is broken
into seven
South Africa
separate
plates
number through
of small plates
the face
ofplus
thea earth
time
South
Pole
The Earth’s Crustal Plates Today
Crustal plates move during geologic time
North American
Plate
Pacific
Plate
Eurasian PlateRecent earthquake
African Plate
Evidence of plate motion
Plate motion in geologic time:
1. moves continents into different climate zones and
E. A. Keller, 1996, Environmental Geology
2. creates mountains whenFrom
the
plates collide
The Earth’s Earthquakes and Volcanoes
Evidence of Plate Motion Today
Recent earthquakes
How were the plates configured
when the Appalachian Mountains were
created by plate collision?
From E. A. Keller, 1996, Environmental Geology
270 million years ago:
(Permian Period)
The Appalachian Mountains have just been
formed by the collision of North America
with South America-Africa
North America
Let’s look at a more detailed map
South
America
Africa
North American plate
A
lookto
atthe
the Appalachian
collision of crustal
plates
Now
Mountains
Check “hidden” figs. 23 thru 28
Plate collision Appalachian Mountains
South American-African plate
European plate
Tramping Geology through the Appalachians
Original music by Bob Blackshear:
Nashville recording artist
Song writer and singer
Sun City Resident
Geology in the News
Tibet-China
6.9
India
Geology in the News
Geology in the News
Nile geosyncline
gas prone
Geology in the News
Nile geosyncline
gas prone
Cyprus Offshore territory
Nile geosyncline
gas prone
Expensive production from deep water (6,000 feet+) Brazil and
Canadian tar sands forecast to provide oil to replace diminishing
resources in Mexico and Venezuela.
Geology in the News
Computer modeling of oil & gas
reservoirs using seismic, drilling,
production, and conceptual data
Now back to the Appalachians
But first, a little about Geologic Time
As we define the history and geology
of the Appalachian Mountains we’ll also
focus on how human history was shaped
by the geological events that created
these mountains
Geologic Time Scale
Appalachian
Mountains
formed
Human
History
Our focus: last 570 million years
Geologic Time: Last 570 Million Years
Appalachian
Mountains
570,000,000 years
Last 5 Million Years
The time of us “humans”
Geologic Time Line: last 5 million years
“Humanoid & Humanid” Fossil History
Now
Oldest
Humanoids
Kenya 1970are
Where
Volcanic mud
Footprints
1978
earlyTanzania,
human
fossils found?
Current Known Earliest Humanoid Fossils
Hot Spots under Africa today
General Area of
Oldest Human
ancestors
A closer A
look
at the view
last 5 million years
closer
From: Ron Redfern, 2000, Origins
Today
You & Me
1 million years ago
2 million years ago
Added NY Times 9-11
3 million years ago
A closer
look: the last 1 million years
4 million years ago
Homo erectus & Homo sapiens
Columbia University
Lamont Geol Inst 2011
Homo sapiens
Homo
neanderthalensis
Times of
Continental Glaciation:
Northern Hemisphere
Homo
rhodesiensis
Focus on Homo sapiens
Homo
Antecessor/
mauritanicus
Homo
ergaster
Homo
erectus
Awesome Humans:
reasoningHomo Fossil Record:
The 1.Current
Expressed in language
2. conscience
Last
300,000
years
3. adapt
to any
environment
4. migrated worldwide in 80,000 years
Time of Written
World History
Last ice age
Human history time line
http://en.wikipedia.org/wiki/File:Humanevolutionchart.png
Human History Time Line:
aka Recent Geologic Time Line
One Million
Years Ago
Now
Next, Eurasia 10,000 years ago
Now
Last Ice Age
AD
human
history
BC
Other views of human migration
Last continental glacier:
North America
Last continental glacier:
Eurasia
Human land
path
Nile River
Rift Valleys
Migration of Humans into Eurasia
Possible Migration Route of Humans
into the Western Hemisphere
More specific routes
Alternate route current theory:
Asia to North America by sea
The awesome challenge of migrating
by sea
Alternate route current theory:
Asia to North America by sea
The awesome challenge of migrating
by sea
Early human artifacts in the vicinity
of the Appalachian Mountains
Evidence of early humans in the Appalachians
Pre-Clovis
artifact sites
But when did they first come to North America?
Might it have been while the glacier was growing
rather than when it was at it maximum extent?
Last Four Ice Ages
Homo sapiens
Looking at the last glacial period
Possible migration of early humans
into North America 35, 000 years ago
Last glacial
period
35,000 years ago
glacial recession
15,000 years ago
pre-Clovis
The big picture
Possible Intra-glaciation Migration of
Humans from Asia to North America
15,000 years ago
35,000 years ago
mid-late glacial period
What did early humans find on
their way to Appalachia?
Possible drainage challenges of
migration during a glacial recession
What might the Canadian portion of
the migration route looked like?
North
South
Glacier
Cold hostile climate!
Possible drainage challenges of
migration during a glacial recession
What did First Nation People find
when they finally got to Appalachia?
Melting glacier
Maximum extent of last glacier
Following the rivers, staying
away from the melting glacier
What did Appalachia look like as
First Nation People approached
it from the west?
A Land of Long Ridges and Valleys
What made the ridges & valleys?
And east of this region
Blue Ridge Mountains
Valley & Ridge province
Next Week
Next Week
First Nation People arrive and
explore Southern Appalachia