Transcript Idaho Geology Virtual Field Trip

A Virtual Field Trip
Welcome to the
Magic Bus and our
exciting virtual
field trip. We will
be traveling
around Idaho and
viewing examples
of many of the
geologic features
we have studied in
this class. Please
submit your
permission slip
now and sign the
bus log.
Here is your trip
sheet for keeping
track of your visits.
This will prove that
you have been there!
Now look over the
field trip check list
to make sure you are
prepared.
Here are our scheduled stops, but remember that you may
magically skip, re-arrange, or re-visit sites in any order simply
by selecting the destination of your choice. Here is the bus
schedule. OK, put on your imaginations and load up for the trip
of your life!
Click on your
desired destination
arrow or click on the
upper right hand
corner of each card
and just hold on for
the whole trip. You
may return to this
location at any time
by clicking on
Does Idaho have fault
zones?
Do we ever have
earthquakes? How
about some history?
Can we exit the bus
and take pictures of
the Challis quake and
near Borah Peak?
Hawaii is a chain
of “hotspot”
islands. Idaho has
something similar,
believe it or not!
Come and visit the
Snake River Plain
in Idaho, with
both intrusive and
extrusive features
on exhibit. And
don’t forget to
stop and tour the
Craters of the
Moon National
Monument.
How about the
Panhandle and
volcanism?
And what,
exactly, is the
Idaho Batholith?
Can we get off
the bus for more
photos?
Idaho has experienced a
lot of glacier action, too.
But was it alpine or
continental in form?
Click on one or the other
to go there and see.
Groundwater mark ~
The subject of
Groundwater brings
to mind aquifers. Do
we have any major
aquifers in our
state?
Click North or South
to visit sites about
some important
aquifers.
What about mass
wasting? I’m sure it
happens all over Idaho
and quite often, as
well. There was an
excellent example in
1998 Bonners Ferry
that you may want to
visit. This bus can not
only move us around
the state in a flash, it
moves back and forth
in time as well. Photo
op!
Surface water
mark
We may not be like Finland
or Minnesota, but there are
plenty of lakes and rivers in
our state. Would you like
to visit any rivers or lakes?
Mining
mark
Geology has historically been important in the
settlement of Idaho. One useful result of geology
is the mining of valuable resources that make our
everyday lives easier and more convenient. Let’s
look at the history of mining in Idaho. And be sure
to click on “Idaho Mining Images” at the end.
Sign the bus log to make the trip!
Name
Date
Name
Date
Name
Date
Trip sheet - Respond to these questions as you travel
and discover information
•
•
•
•
•
•
When and where was Idaho’s largest earthquake?
Name 5 volcanic features found at Craters of the Moon Monument.
Name the major example of continental glaciation in North Idaho.
Identify the largest aquifer in the state.
Explain the mass wasting event in 1998 Bonners Ferry.
In which county do you find Lake Pend Oreille and the origin of the Payette
River?
• What geology-related event lead to the establishment
of the Idaho Territory?
And place the special marks found at each destination in the chart below.
Quakes
Volcanism
glacier
Ground Mass-water
wasting
Surfacewater
Mining
Virtual Field Trip Check List
Have you handed in your permission slip?
Have you picked up your trip sheet?
Do you have warm clothing, including rain gear? Remember to
dress in layers because we will feel the warmth of the bus and the
chilly spring weather outdoors as we explore and take pictures.
Do you have your lunch and an extra snack? Bring enough of your
tasty snack to share with your teacher?
Do you require any special things: Deep Woods Off, sunglasses,
sun block, Benadryl for bee stings, etc. ?
Do you have your camera, field notebook and a writing utensil for
taking notes, responding to questions, and writing down what your
pictures are meant to show?
Do you have your I-Pod and cell phone? Turn around and take them
back to your mom in the car………you won’t require them.
Did you pack your imagination?
Faults Found in Idaho
New data from the
Clearwater complex,
north-central Idaho,
define the origin and
history of the
complex. The
complex is divided
into an external zone
bound by normal
faults and strike-slip
faults of the Lewis
and Clark Fault Zone
(LCFZ) and the
associated
Noxon/Moyie Fault
Line, and the smaller
faults into adjacent
Washington,
Montana, and Canada.
Faults Found in North Idaho
Faults Found in North Idaho
Central and Southern Idaho have some rift zones (areas of
faults) as well. The areas around Challis in Central Idaho and the
Basin/Range and Middle Rockies regions have earthquake
potential as well as formations based on parallel fault lines. So
have we ever had a major earthquake in Idaho?
Return to the bus, please.
Earthquake mark

The Snake River Plain is a broad arcuate topographic
depression that extends across southern Idaho (figure 1 below)
The western Snake River Plain sits in a fault-bounded graben
while the eastern Snake River Plain (ESRP) is a large structural
downwarp that formed due to the weight of the overlying
volcanic rocks. The Owyhee Plateau is genetically related to the
Snake River Plain, although it has remained a highland region.
The map below shows the geography of the Snake River Plain
and surrounding areas.
Current studies suggest that the Snake River Plain resulted
from the passage of the North American Plate over a
stationary mantle plume or “hotspot” that is currently located
beneath Yellowstone National Park (Figure 2) or what is often
referred to as the Yellowstone Caldera or Yellowstone Plateau.
The North American plate migrates at a rate of approximately
4.5 mm/year over the "hotspot".
OK, kids, back on the bus!
Cameras away, return to the bus.
Volcanism mark
The Idaho Batholith is composed of
Cretaceous granite and covers approximately
35,000 km2 in central Idaho; it is roughly 320
kilometers long by 120 kilometers wide, and 8
kilometers thick. The Atlanta Lobe and the
Bitterroot Lobe of the Idaho Batholith are
separated by metamorphic rocks in the
Salmon River Arch. The Atlanta lobe is older,
100 to 75 Ma., while the Bitterroot lobe is
mainly 85 to 65 Ma. There has been debate
about the inclusion of the Kaniksu Batholith
as part of the larger Idaho Batholith. Its
geologic make-up makes it of similar origin,
however. The Kaniksu Batholith or Lobe,
which makes up the north/south trending
Selkirk Mountains, located in the northern
portion of the core complex, is a mixture of
granite and granodiorite of the same type as
the rest of the batholith and is of the same
Cretaceous origin in age.
The granitic rocks of the Idaho
Batholith formed during late
Cretaceous compression event. At this
time, the dense oceanic Farallon Plate
was subducted beneath the more
buoyant continental North American
Plate. The oceanic crust was
subducted into the lithosphere until
heat, pressure, and slab dewatering
initiated melting of the oceanic plate.
This melting and the superheating of
water that was also subducting formed
basaltic magma chambers. These
chambers rose up through the
lithosphere because of differences in
buoyancy. They then caused partial
melting of overlying continental crust,
to form a melt of
granitic composition.
Return to the bus, it’s
almost lunch time!
There are many examples of
alpine glaciation in Idaho,
especially in the high peaks of
the Bitterroots that form the
boundary and continental divide
between Idaho and Montana, as
well as higher regions of Central
Idaho like Sun Valley and McCall.
Glaciation occurs
at high latitude,
as well as high
altitude as seen in
Idaho.
Continental glaciation is evident in the northern Panhandle. The
Purcell Lobe of the Cordilleran Ice Sheet wandered down during
the Ice Ages and retreated several times. This left behind some
large glacially-scoured lakes (Pend Oreille and Priest) and a
glacially dammed lake (Coeur d’Alene). It also resulted in the
formation of the gigantic Glacial Lake Missoula, responsible for
the Spokane Floods that reshaped parts of the Panhandle, as well
as Eastern and Central Washington.
The following drawing and aerial photo explains how the Purcell
Trench and Lake Pend Oreille may have been carved out from
existing rock structure.
The trench stretches from Coeur d’Alene in
the south, all the way into Canada. Now let’s
head back to the bus.
Glacier mark