WEBVTT

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Hello and welcome to Grand Canyon
National Park.

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Because I am at a safe social distance
from others around me,

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I can lower my mask and speak to you
more directly.

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My name is Ranger David and we have
Ranger Miren,

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Rachel and Kevin behind the camera
helping me today.

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I am standing at the large, stone Bright
Angel Trailhead sign on the rim of the canyon.

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Today we will
be doing a virtual rim walk

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along the portion of the rim trail off
of the Hermit's Rest road.

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On this map you can see the eight
stops we will make starting here,

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and ending at Powell Memorial Point 1.7 miles or 2.8 kilometers up the trail.

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We will be sharing some human history of Grand Canyon and what makes this the grandest canyon of them all.

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It's another great day here at the canyon.
Let's get started!

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*Upbeat music plays*

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Our first stop is at the Bright Angel
Fault where our trail takes a dip.

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This depression in the landscape, created
by an ancient crack,

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continues across the canyon like a giant
trough,

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elevating one side of the rock layers
200 feet above the other.

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During this walk I will
be discussing geologist Wayne Ranney's

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five independent factors that
make this the grandest canyon of them all.

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The first factor is the thick stack of stratified rock that we find here at the Grand Canyon.

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You could describe these layers as
pancakes stacked on top of each other.

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The youngest rock layer is on the top,       
 it is called Kaibab Limestone

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which geologists tell us is 270 million years old.

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Where did this layer come from? Millions
of years ago this area was at sea level

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and was covered by a warm shallow sea.
This artist's rendition

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of the archaic sea shows an ancient
shark

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swimming past sea sponges and
other ancient types of shellfish called brachiopods.

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Over millions of years the
limestone was compressed into the layer here today.

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There are 11 horizontal
layers of different sedimentary rocks

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shown on this slide, depicting a cross
section of a wall of the canyon exposing the 11 layers.

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These sedimentary rock layers stacked together, make up four thousand feet of the canyon's walls.

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Let's head up the trail to our next stop!

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*Upbeat music plays*

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Here I am on the west rim of the canyon
overlooking the buildings of the historic village.

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We can also see the Bright Angel Trail snaking down the side canyon below us.

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Native Americans have been living in and around this area for thousands of years.

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Today there are 11 tribes that have  a strong association with the canyon.

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Unfortunately, National Park Service was involved in the displacement of many of these peoples.

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The current locations of these 11 tribes
are depicted on the map,

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showing the areas surrounding the canyon.

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Early pioneers at the canyon in the 20th century included the Kolb brothers.

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Ellsworth and Emery Kolb
arrived here in 1901 and 1902 respectively

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and began a photography business.

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They asked Mr. Ralph Cameron if they could set
up a tent to use as a photography studio.

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Mr. Cameron had laid down mining claims
in this area which was allowed in those days.

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They later built Kolb Studio, a brown building with the yellow window trim

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built quite literally on the edge of the canyon with
windows facing the canyon on three sides.

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From there they took pictures of the
mule riders going into the canyon

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on the Bright Angel Trail to sell to
them later.

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The large brown wooden building with the
cupula on top,

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behind the Kolb Studio, is the El Tovar
hotel.

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This hotel, built in 1905, was considered
to be the most deluxe hotel west of the

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Mississippi River.
It had running water, electricity

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vegetable gardens and a dairy herd
outback.

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Now on to our next stop!

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*Upbeat music plays*

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At this stop we can appreciate the vivid and varied colors of the canyon's rock layers.

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These colors vary due to the different
types of rock and the mineral content.

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We can see brown, red, orange, beige and even a hint of green when we pan into the canyon.

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The vivid and varied colors are the second factor
that make Grand Canyon one of the seven

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natural wonders of the world.
The only canyon and the only wonder on

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the North American continent
from that short list.

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Let's find out the third factor at our next stop!

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*Upbeat music plays*

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We have talked about the layers of very
old rock here

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at the canyon, and how this area used to
be at sea level.

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60 million years ago, two tectonic plates
collided.

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The Pacific Plate collided with the
North American Plate

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lifting it up and creating the area
known as the Colorado Plateau.

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Today on the south rim we are at seven
thousand feet above sea level.

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This is a map that shows
the areas that rest on top of the Colorado Plateau.

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The plateau extends from western Colorado, southern Utah, western New Mexico and northern Arizona.

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The uplift of the plateau was so huge that the rock layers of the canyon remained relatively horizontal.

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The uplift is our third independent factor.
Let's continue on up the trail!

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*Upbeat music plays*

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At this spot on the rim, we have an
expansive view of the canyon.

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We talked about the colorful rock layers,
but could we see them if we're in a more

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temperate climate
with much more vegetation?

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The fourth independent factor
is the semi-arid climate here in northern Arizona.

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Within the park there are five life zones. With very little precipitation and lack of rich soil,

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very little vegetation covers the canyon
walls.

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There are beautiful canyons elsewhere on
our planet,

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but some of their walls are hidden by
vegetation.

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Here we are able to see the beautiful
exposed rock layers.

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Looking down into the canyon,
the Bright Angel Trail continues down

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through Indian Gardens,
which is a patch of green oasis in the

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otherwise sparsely vegetated canyon.
The green patch is due to leafy

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cottonwood trees that shade the
backcountry campground there.

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It is a four and a half mile hike to
Indian Gardens and another three

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and a half miles to the Colorado River.

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At our next stop we can see a little bit of that Colorado River.

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*Upbeat music plays*

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Here at Maricopa Point we have a view of
a small green blue sliver of the Colorado River.

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There are many other areas with viewpoints of much more of that beautiful river.

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I have mentioned four out of the five independent factors that make this the grandest of canyons.

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Let's review the factors, and they are:
layers of sedimentary rock stacked on

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top of one another,
vivid and varied colors, uplift of the Colorado Plateau

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and we are in a semi-arid climate.

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The fifth factor is the Colorado River.

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Geologists tell us the river has been carving the canyon
for about 6 million years.

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That tells us that we have
old rock but a young canyon in geologic time.

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The Colorado River is currently controlled by the Glen Canyon dam

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approximately 100 river miles upstream.

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From here it may not look like a
powerful river, but this photograph

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of a commercial raft, maneuvering through
those huge splashing rapids

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gives you a better understanding of the
power of the Colorado River.

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There are other rivers in a desert
environment powerful enough to have carved a canyon.

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This includes the Nile River in Egypt

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and the Tigris Euphrates rivers in Iraq.

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However, the areas these rivers rest on were not
uplifted.

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You must have uplift for a river to carve a canyon.

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Here at Maricopa Point there is also human history.

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Over the rim we can see the remains of the Orphan Mine.

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John Hogan came west seeking his fortune in the late 1800's.

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He filed a mining claim here and started mining copper.

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If we look over the rim we can see the metal remains of the mine's head frame

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and a large hole in the rock, the old entrance to the mine.

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Eventually Hogan's interest turned towards the growing number of visitors

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and he built the Grand Canyon Inn on the rim.

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Here are two
early 1960's photos of the inn,

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a wooden barn-like building right on the
canyon's edge

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with a small pool that looked like a
water-filled balcony.

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That looks so refreshing on a hot
summer day.

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The inn existed from 1936 to 1966
but Hogan sold his mining rights in 1946.

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In 1951 uranium was discovered in this
very spot.

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A new shaft was drilled into the rim to
increase production of the ore.

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The mine existed until 1966.

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It's hard to believe that uranium was mined once
in one of your national parks.

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As we walk to our final stop, we will pass by a
fenced-off area on the canyon side of the path,

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that has not been declared safe for us to enter
due to the old uranium mine.

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*Upbeat music plays*

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We're at the memorial to John Wesley
Powell,

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a large pyramid-shaped structure built out of limestone.

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The steps of the memorial lead to a view of the canyon
and to a plaque dedicated to the great boatman.

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Powell was a self-taught geologist who, in 1869,
led an expedition starting at Green River Wyoming

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down the Colorado River to document this area.

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Before his expedition this area of the southwest was labeled the "Great Unknown"

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on maps of what is now the lower 48 states.

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This expedition quickly turned into a fight for survival
when one of the four wooden boats,

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carrying much of the food supply
and geologic instruments was lost in a rapid.

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After three months on the river, the expedition reached a small settlement down river from the canyon.

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By then, only five of the nine crew
members remained.

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In 1872, Powell returned to better
document the canyon and the river.

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We have now discussed a little geology
and human history of the Grand Canyon.

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And the five independent factors that
make this canyon the grandest of them all.

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There is much
more to learn and appreciate here,

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I hope you can visit and explore Grand
Canyon in the future.

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It is truly a natural wonder. Thank you
for joining me today!

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*Upbeat music plays*