Transcript File - Vagabond Geology

SAGE Fall 2010
Session 3
Carlsbad to the Rio Grande Rift
Vagabonds Tramping Geology:
Austin to Arctic Alaska
The impatient thrust for scholarship
is the secret of youthfulness:
the undying flame that lights
the human spirit
Senior University
Fall 2010
Session 3
Carlsbad to the Rio Grande Rift
Vagabonds Tramping Geology:
Austin to Arctic Alaska
Geology in the News
Rare earth metals are a collection of seventeen chemical elements in
the periodic table, namely scandium, yttrium, and the fifteen lanthanides
Uses: hybrid cars, superconductors, television sets, welding, munitions, etc
Geology in the News
Geology in the News
Large area of interior drainage
due to glacier melting 12,000 years ago
Geology in the News
From the minute to the sublime
Putting It All Together
Last Glacial Maximum: 16,000 years ago
Geology in the News
Deposition and Burial
before Uplift and Erosion
Area for
Water wells
Carrizo Sandstone
Geology in the News
Geology in the News
USA
Territorial
waters
Putting It All Together
The Earth’s Amazing Living Crust
Living: it reproduces itself
Continental Crust: Periodically Renewed
Oceanic Crust: Continuously Recycled
4.8 billion years ago cooling of hot
gases and dust created igneous rocks
of the continents & oceanic crust
Granites first
Foundation rocks
of the continents
After the atmosphere and oceans were formed:
Then the oceans and the atmosphere
Basalts & Gabbros next
Foundation rocks below the deep oceans
AND
below the continental crust.
After the atmosphere and oceans were formed:
The granites at the surface of the continents were
weathered and eroded into:
Clay and Sand
and
The clay & sand were carried by rivers to the oceans
and deposited at the continental margins
Burial of the clay and sand produced sedimentary
rocks of shale and sandstone
Deformation of Continents:
and
Two Types
Rocky & Cordillera
mountains
Deformed sedimentary rocks
Metamorphic rocks
Igneous granites and basalts
Mountain building along the continental margins
melted the sedimentary rocks producing:
Metamorphic rocks (partially melted) and
Igneous rocks (completely melted)
Deformation of Continents:
Two Types
Rocky Mountains
The history of the 2.Oceanic
Crust
Continent warping
Result: Major rivers concentrate
creatingerosional
major rivers
debris
in thebuilding:
oceans at thethat
continental
margins
deposit erosional
1. Mountain
debris
alongback
the coast
of two
Andcollision
plate collisions
weld that
debris
into
or more crustal
plates
the continent
as mountains
Oceanic Crust: Basalt 5 miles thick
Continuously Re-cycled
Oceanic crust is
melted as it is
over-ridden by
continental crust
The North American Pacific Example
New oceanic crust is
created in oceanic ridges
Resulting in:
Oceanic crust is 0 to 250 million years old
Continental crust is 0 to 4.8 billion years old
Earth’s Crust: Plates
Earth’s Crust: Plates
Pacific and North America
Earth’s Crust: Pacific and North American Plates
Back to our route to New Mexico
Recent Rocky Mt
Debris
A Closer Look on Our
Way to New Mexico
“Recent River debris from
the rising Rocky Mountains
on top of older rocks
How
far did
this
river debris extend?
From: Roadside
Geology
of Texas
Recent Erosional Debris in Texas
from the Mountains of New Mexico
Gravels
&
Sands
Recent Debris in New
Sands
&
Mexico Muds
Recent Debris in New Mexico
Recent gravels
& sands from
rising Rocky Mts
Now the big picture in North America
Earth’s Crust: Plates
Pacific and North America
Melting
Continental
Glacier
Hypothesis: Yellow: recent debris
from the rising mountains that
might have provided the access
to the Americas for early humans
migrating out of Siberia
A quick look at the advent of humans
Homo sapiens
Homo
neanderthalensis
Times of
Continental Glaciation:
Northern Hemisphere
Homo
rhodesiensis
Homo
Antecessor/
mauritanicus
Homo
erectus
The Current Geological Record
on the
on the Advent ofFocus
Humans
Homo
ergaster
last 80,000 years
Time of Written
World History
Uniquely human characteristics?
1. Reason
2. Conscience (right & wrong)
3. Adapt to any climate
Last ice age
Missing Link?
Now, a look at the human migration route
Nile River
Rift Valleys
Location of earliest
human fossils
Possible Migration Route of Humans
Back to our journey to New Mexico
Rocks of Central & West Texas
Permian Rocks 260 million years old
Permian rocks
at the surface
The big Permian picture
Thickness Map: Permian Period
Permian Basin
A Cross Section of the Permian Basin
Permian Reef
at the surface
Reefs
The oil fields of the Permian Basin
P B King; The Evolution of North America, 1959
The oil fields of the Permian Basin
Now, into New Mexico
Two drainage
systems
Only copper and coal
no tin or iron
Little farming land
But the geology is fantastic!
Natural Resources
Present day
surface
Rift
Graben
Trench
Continental
Crust
A cross section of the Rio Grande Rift
Mantle rock (hot!)
The Rio Grande Rift (graben)
Eastern
Horst
Western Horst
Graben partially filled
with debris from
bounding horsts
From Roadside Geology of New Mexico, Chronic, Halka, 1987
Focus: Eastern Horst
Carlsbad to Roswell to Alamogordo
Geologic Map: Southeast, NM
Mountains on
the East Horst
Orange= non volcanic
red = volcanic
Sierra Blanca
Igneous Mountains
Igneous Rocks and Rifts
Sierra Blanca
Igneous Mountains
Sierra Blanca
Igneous Mountains
Present day
surface
Graben
Continental
Crust
Mantle rock (hot!)
Sierra Blanca Mountains
Volcanic Igneous rocks: Tertiary Age
Geologic Map: Sacramento Mountains
Recent Rift Valley
fill debris
Geologic Map: Sacramento Mountains
Rocks at the surface
Permian
Pennsylvanian
Lower Paleozoic
Pre-Cambrian
How thick are these pre-Permian Rocks?
Cross Section of Eastern Horst
Recent fill
Now, going west across the
Pre-Cambrian
continental
Rio Grande
Rift
foundation rocks
Road Map: New Mexico
Crossing the Rio Grande Rift
White Sands
Modified Space Photo
White Sands
White Sands National Monument
Crossing the Rio Grande Rift
San Andres Mountains
San Andres Mountains
White
Sands
http://en.wikipedia.org/wiki/San_Andres_Mou
ntains
San Andres Mountains
Complex Up-thrown Fault Block
in middle of Rio Grande Rift
Involves Permian & Tertiary sedimentary rocks
Contains rhyolites & granites (continental crust melted)
Present day
surface
Graben
Continental
Crust
Mantle rock (hot!)
Crossing the Rio Grande Rift
The Western Horst
Plains of St. Augustine
San Andres Mountains
Datil-Mogollon
Volcanic
highlands
What is a Caldera?
Answer:
A “granitic”** volcano that has blown off its top
**Granitic = melted continental crust
Explosion!!!!
Collapse !!
Caldera
Volcanic Explosions: Mt. St. Helens
Tambora in Indonesia Largest known
Volcanic explosion
In human history!!
Mt. St. Helens
.25 cubic miles
of ash!!!
Volcanic
Ash
Tambora
36 cubic miles
of ash!!!!
Volcano
Earth
Indonesia, Island of Sumbawa
Indonesia
Indonesia Sumbawa Island Tambora
Volcano
Sumbawa
Island
Tambora Volcano, Indonesia
Largest in Human History
Mt St Helens
.25 cubic Miles
Tambora
36 cubic Miles!
Two of Three Volcanic Explosions
at Yellowstone
Lava Creek
Volcanic
Explosion
Huckleberry
Ridge
Volcanic
Explosion
600 cubic miles
of ash!!!!!
Yellowstone Volcanic Explosion
Calderas!!!
Tambora
36 cubic miles
Mt. St. Helens
Lava Creek & Huckleberry
Ridge, 600 cubic miles!!!
Yellowstone’s
Three Explosion Calderas!!!
Yellowstone
Explosion Calderas!!!
Next Week
Arizona and California
Colorado
Plateau