Geology 143A: Field Course to
Northern Arizona
Led By: Dr. Charles
Merguerian, Chairman, Geology
Department
Spring 2010 Spring Break
(March 27-Apr 3, 2010)
Through an integrated lecture and
field course, students investigated
the geology of northern Arizona.
The goal of the course was to
create and to provide an
experience-based introduction to
geologic field observation and
mapping and to see, first-hand the
methods necessary to collect and record data. Stops centered in the vicinity of Flagstaff, Arizona
allowed Hofstra students to examine the geology of Red Rock State Park, Oak Creek Canyon,
the Jerome mining area, Mingus Mountain, the San Francisco volcanic peaks, Sunset Crater,
Wupatki, Meteor Crater, the Petrified Forest and culminated in a hike into the Grand Canyon.
Students were exposed to field observation, measurement, analysis and interpretation in the
subdisciplines of structure, stratigraphy, volcanology, petrology, field geology, cartography,
mineralogy, and geochemistry.
The course was arranged stratigraphically with the
oldest terrains studied first. Our investigations
began in the area of Jerome, where 1.8 billion year
old rocks were exposed on the flanks of Mingus
Mountain (right and below). Oddly eroded slightly
younger granitic rocks were examined next in the
area of Prescott (next page) – just over the “hill”
from Jerome.
1.8 Ga metamorphic rocks of Mingus Mountain.
(Note: All digital images by Prof. C. Merguerian.)
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Granite “Dells” of Watson lake Park in
Prescott, AZ
The second day was spent in the area of
Sedona, where the structure and
stratigraphy of “red rock” country was
investigated via a series of short hikes
(left). Time for fun was found easily at
Slide Rock State Park (below).
Students relaxing after a short hike in “Red
Rock” country.
Recreational exercise at Slide Rock State
Park.
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The San Francisco Peaks (Mt. Elden,
Sunset Crater, etc.) were the target
for our next day’s excursions where
students were exposed to volcanic
flow features and structures and
were allowed to walk through the
Bonita Flow, dating back only 1000
years before present.
Bonita lava flow at Sunset Crater.
View of highly oxidized vent of Sunset
Crater.
Later that day, we examined the
Indian ruins at Wupatki and learned
about the integration of people and
geology in the way that the rocks
and land were utilized for survival.
Wupatki Indian Ruins.
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The next day we headed east of
Flagstaff to Meteor Crater and the
Petrified Forest. Here we
examined the deformed rim of
meteor crater the direct result of a
50,000 year old impact with a
hypervelocity iron-nickel meteorite
strike.
View of Meteor Crater, near Winslow,
AZ.
One of our students served as a tour
guide at the Petrified Forest during an
internship with the National Park
Service a year earlier sop we were
treated to a new lecturer for the day.
Mr. Adrian Flores (pictured to left) led
the discussions that afternoon where we
made numerous stops to examine the
unique “badlands” erosion and
topography and the petrified logs and
wood that have made this park famous.
The “Chocolate Hills”, part of the Petrified
Forest’s many unusual landforms.
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Student examining logs at the Petrified
Forest, near Holbrook, AZ.
Two final days at the Grand Canyon was the
capstone experience of our week-long field
course. We spent the first day (left and below)
examining the canyon from a distance. Here,
through a series of integrated stops, we
established the stratigraphic relationships of
the region in totality by splicing together what
we had seen elsewhere into a comprehensive
picture. For example (next page) the same 1.8
billion year old rocks exposed in the core of
Mingus Mountain were seen in the inner gorge
of the canyon, where down cutting of the
Colorado River has exposed them for view.
View into the Grand Canyon along the Bright Angel
fault.
Students posing along the south rim of the canyon after their first view.
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Telephoto view of the inner gorge of the
Grand Canyon showing steeply inclined
1.8 Ga metamorphic rocks beveled by
near horizontal strata of the Paleozoic
Era with 1.2 billion years of time
missing at the contact (unconformity).
Our second day in the canyon was
spent hiking down the Bright
Angel trail to examine the details
of the rock types, their structure,
and fossils. A bit treacherous in
early April with snow and ice on
the trail, we managed to hike
down a few miles into the canyon
before heading back out for a
photo opportunity in a canyon rim
tree (below left) and then later at
the gorge of the Little Colorado
River (below right).
Hikers along the Bright Angel Trail.
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