esas0703temp_LateCzSw-stu

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Unformatted text preview: (U.S.
Geological
Survey,
2007) The
Late
Cenozoic
Southwest (Late
Neogene
‐
Quaternary
Periods) EARTH
SCIENCE
in ARIZONA
and
the SOUTHWEST Monument
Valley,
Navajo
Nation,
Utah‐Arizona Geologically
recent
volcanism Right
inside
one
of
the
hills there
was
a
mass
of
what
looked
like boiling
coals
pushing
upward… Sunset
Crater,
Arizona
(<
1000
ya) Bursts
of
sparks kept
shooting
into
the
air just
as
from
a
torch someone is
running
along
with… Spewing
forth
in
every
direction, the
molten
embers
started running
everywhere. From
all
appearances, the
flow
was
heading
straight toward
the
village
of
Musangnuvi. From
Earth
Fire: a
Hopi
story
of
the 1065
AD Sunset
Crater
eruption, Ekkehart
Malotki and
Michael
Lomatuway’ma SP
Crater,
Arizona
(70,000
ya) The
Late
Cenozoic Southwest (all
photos:
U.S.
Geological
Survey) 2 The
Northern
Hemisphere
entered
the
modern
Ice
Age Since
then,
ice
has
cyclically advanced
and
retreated,
each
time leaving
geologic
evidence
of
its presence The
last
 glacial
maximum (Wisconsinan)
 35‐12
ka Stanley
(2005) Peak
~
20
ka The
Late
Cenozoic Southwest 3 Changes
in
oceanic
circulation
may
have triggered
the
Neogene
Ice
Age Thermohaline circulation: the
oceanic
 “conveyor
belt” Stanley
(2005) Closing
of
Isthmus
of
Panama
retained
saltier
Atlantic
waters,
which
then began
to
sink
before
they
could
warm
the
Arctic The
Late
Cenozoic Southwest 4 The
oscillations
in
glaciation
(maxima
&
minima)
may
reflect periodic
changes
in
Earth’s
rotation Modifies other effects Early
 (pre‐850
ka) oscillations Later oscillations Stanley
(2005) The
Late
Cenozoic Southwest 5 Mountain
glaciation
and
glacial
lakes
during
ice
ages Dried
up
beginning
about
15,000
years
ago The
Late
Cenozoic Southwest (Reynolds,
Johnson,
Kelly,
Morin,
&
Carter,
2008) 6 Terraces
are
remnants
of
former
valley
floors
incised
by
streams. Highest terrace Middle terrace Highest terrace Lowest
terrace Modern
floodplain Active
channel Reynolds,
Johnson,
Kelly,
Morin,
&
Carter,
2008 The
Late
Cenozoic Southwest 7 Formation
of
terraces Early
river
level
with
floodplain Downcutting
forms
new,
lower
floodplain, stranding
terrace Changing
flow conditions
leave
a
series of
terraces. What
could
account
for these
changing
flows? 1 2 3 Reynolds,
Johnson,
Kelly, Morin,
&
Carter,
2008 High
terrace
is
the oldest,
followed
by
each
lower terrace (stratigraphy
is
reversed) 8 The
Late
Cenozoic Southwest Terraces
of
the
Salt
River (slide
by
J.
Block,
2006) Tread Riser The
Late
Cenozoic Southwest (Péwé,
1970) 9 Salt
River
terraces •Slope
more
steeply
upstream •Increase
in
relative
elevation
from
the
active
channel
upstream •Slope
more
steeply
with
age Implies
that
older
channels
had
higher
incision
rates Sawik Blue
Point Lehi Mesa 20x
exaggeration North The
Late
Cenozoic Southwest (Block,
2006) 10 Surface
processes
in
deserts Dust
devil,
NM (G.
Hincks
in Marshak,
2001) The
Late
Cenozoic Southwest 11 Groundwater
is
a
geologic
agent Formation
of
alcoves
and
arches The
Late
Cenozoic Southwest 12 Dynamic
processes
=
Geologic
hazards Earth
fissure
near Willcox,
Arizona (L.
Allison
photo) Rockfall
partially covers
highway, Bluff,
Utah Queen
Creek,
Superior,
Arizona The
Late
Cenozoic Southwest 13 Groundwater
depletion
leads
to subsidence
and
fissuring Marshak
(2001) The
Late
Cenozoic Southwest 14 The
“Anthropocene” Phoenix, Arizona Warning of uranium pollution, Navajo Nation, New Mexico Copper mine, Ray, Arizona Smog in the Valley of the Sun, Arizona The
Late
Cenozoic Southwest 15 It
is
an
honor
to
walk
where
all
around
me
stands
an
earth
house
made
of
scarlet,
of
jet, of
ochre,
of
white
shell. It
is
more
than
beautiful
at
the
center
of
the
world. Joy
Harjo Four Peaks and Sonoran Desert landscape, Arizona ...
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This note was uploaded on 03/01/2011 for the course GLG 394 taught by Professor Semken during the Fall '10 term at ASU.

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