GUIDE
TO THE SCENIC DRIVE
Although
this "tour" is free, there is a $4 entrance fee
when you come to the park to drive the Scenic Drive.
STOP
1
Most
rock at Capitol Reef is sedimentary, meaning it
was formed in layers from loose materials - sediments
- like mud and sand.
Geologists have classified the rock layers into
various formations. Many formations also have different
parts, or members.
These layers entomb the landscapes and lifeforms
of a younger planet Earth.
In the hill to the left, thin beds of reddish-brown
rock known as shale were formed from silt and clay
that came to rest in the quiet waters of lagoons,
mud flats, and coastal flood plains. This 225 million
year old rock is the Moenkopi Formation. Geologist
believe that the Moenkopi, more than 950 feet thick
in places, was laid down in a moist, tropical climate.
The gray band of rock just above the Moenkopi is
a greenish-gray shale that was once volcanic ash.
Its one part of the Chinle, a complex, 700-foot
thick formation that is rich in petrified wood.
The Chinle ascends to the base of the reddish wall.
STOP
2
From
here you can see the rugged western face of Capitol
Reef.
The tale of how these cliffs, canyons, and domes
formed is complex, but the view from here tells
the essentials of the story.
First, see how rock bands of differing thickness,
colors, and textures lie one upon another like layers
of a cake? The rocks of Capitol Reef were once sediments
- silt, sand, clay, volcanic ash, and gravel - laid
down in many different environments during the Age
of Dinosaurs, and long before. The younger rocks
lie on top of the older rocks.
Second, notice the tilting of the rock layers. When
the Colorado Plateau was born, enormous pressures
deep within the earth buckled the already ancient
rock beds here into a 100-mile-long - but relatively
narrow - "fold.". Geologists called this the Waterpocket
Fold because of numerous small potholes or "pockets"
found in the area that can hold rainwater. Third,
study the maze of shapes carved out of the tilted
rock layers. The Waterpocket Fold has been under
heavy attack by erosion since its creation. Capitol
Reef is one of its remnants.
"Erosion"
means not only the crumbling of rock by frost, plant
roots, and internal water seepage, but also the
blowing or washing away of the particles.
Remember these three elements of the geologic story
- sedimentary rock, folding, erosion - and few landforms
at Capitol Reef will remain a mystery to your for
long.
STOP
3
The twisting Grand Wash spur road takes you into
a world dramatically different from the dark red
hills along the base of Capitol Reef. Avoid this
road when a storm is threatening. Grand Wash is
a narrow, steep-walled canyon subject to dangerous
flash floods that often arrive with little warning.
Beyond a one-mile drive, foot trails lead into the
narrowest, most spectacular part of the canyon and
up to a graceful curve of stone arch on the canyon's
north wall - Cassidy Arch. The arch was named for
turn-of-the-century outlaw Butch Cassidy, who is
thought to have hidden occasionally in Grand Wash.
Notice the holes at the base of a layer of yellowish-gray
rock. This is the abandoned Oyler Uranium Mine,
opened in 1904 when uranium was used in some "over
the counter" patent medicines. This rock crumbles
easily so keep back from the entrance.
STOP
4
At
stop number one you saw the rock layers of the
Moenkopi Formation that were once silt and clay.
It wasn't hard to visualize their flood plain
origin.
Look closely at the massive, sheer cliffs. Focus
on the base of the wall below. Do you see sweeping
lines that intercept one another at varying angles
in the rock? This is crossbedding. Where crossbedding
occurs on a large scale like this, it means that
here once drifted the windswept dunes of an ancient
desert.
Sediment becomes rock when it is buried and compacted
by huge overlying loads of other sediment. Individual
sand or clay particles are cemented together by
minerals in seeping ground water.
As ages pass, the cement of the ancient rock is
dissolved by weak acids in rainwater. Small cracks
in the rock are widened by frost and plant roots.
The rock washes away in chunks and particles. This
is what geologists call weathering, part of the
larger process of erosion.
Shallow holes you see here in the cliff are being
excavated as erosion removes more weakly cemented
sand grains.
A few small, weather sculpted arches can be seen
in Shinob Canyon, which cuts in the south wall of
Grand Wash to your right. Cassidy Arch is nestled
high in the cliffs to your left.
STOP 5
There
are more plants in Grand Wash than on the red
hills at the start of the Scenic Drive. Although
relatively naked stone - slickrock - dominates
the landscape here, plants also are plainly visible.
Although the channel beyond the bank to your right
carries no water most of the time, it does occassionally.
Many plants thrive nearby.
Some, like Apache-plume, are rarely found away from
washes such as this. Other species here like rabbitbrush
also tolerate drier environments.
There can be too much water. In the continuing process
of erosion, flash floods roar down the canyon carrying
debris that crushes and smothers vegetation.
In effect, plant life survival means a compromise
between a demand for water and a need for protection
from floods.
STOP
6
The road now winds through an older, deeper part
of the familiar red shales of the Moenkopi Formation.
Here, however, fairly uniform layers of sandstone
can be seen among the red shale beds, often forming
small ledges.
As you saw in Grand Wash, the towering walls of
Wingate Sandstone were deposited originally as dunes
in a vast desert. If you take a close look at the
thinner beds of sandstone here in the Moenkopi,
you will see signs that this sand was deposited
by water.
The sweeping lines of crossbedding that form in
dune sands are missing here. The surfaces of many
slabs are covered with ripple marks and mud cracks
that formed when wet mud dried under a hot sun.
Sometimes people find the tracks
of an exintct, primitve reptile called Chirotherium
in the rock slabs.
This sandstone was laid down not be desert winds,
but by the gently moving, shallow waters of coastal
tidal flats.
STOP 7
This is Slickrock Divide, separating two large
drainages.
Between stop number two and this hill, streambeds
channel rain runoff and debris to the flash floods
that thunder down Grand Wash. South of here, streambeds
channel their waters into Capitol Gorge.
Think again of the large expanse of bare rock exposed
to the sun, wind, and rain. When rain does come
to Capitol Reef, it often descends in torrents.
Thin patches of soil can do little to absorb and
hold it.
Poets sometimes speak of water as "carving the face
of the land". However, the main role of rushing
water in shaping Capitol Reef is not to gouge, but
carry away the materials already loosened by weathering.
Gravity draws lossened debris to washes where it
can be picked up by moving water. In desert thunderstorms,
this slow process of gravitational "creep" is accelerated
by deluges that wash down every slope and flush
loose debris into channels that soon fill with a
tumbling, red torrent.
Imagine all the torrents of a plateau coverging
upon a single gorge and you will realize how floods
develop in a "flash". If you can picture millions
of storms pounding this land thorugh the ages, you
will have begund to grasp fully the one process
that has shaped Capitol Reef.
STOP
8
Here you see again a formation you've come to
know well on your drive - the reddish brown Moenkopi.
This is a good place to point out a rock layer
that is not visible - rather doesn't exist - near
the park visitor center.
At stop number one, the Chinle Formation rested
directly on top of the Moenkopi. Here, a not-too-thick
layer of sandstone - the Shinarump - caps the uppermost
bed of the Moenkopi and lies below the few visible
greenish-gray remnants of the Chinle. The yellowish-gray
Shinarump is very distinct and you can see clearly
a small remnant of the Chinle. Why do you think
the Shinarump just below the remnant appears greenish
gray?
Shinarump is found only here and there at Capitol
Reef, which hints at the way it was deposited. Apparently,
the Shinarump sediments were laid down in the channels
of rivers that meandered across a coastal plain
200 million years ago. Shinarump is composed of
sands and gravels like those in many shallow river
beds today.
This sandstone is often rich in uranium. The old
mine tunnels you saw at stop number three were dug
into Shinarump.
Incidently, Shinarump also affects the number and
variety of plants growing here today.
Notice how the Shinarump ledge erodes into debris
that litters the clay slopes beneath. This rock
rubble forms a protective cover that slows down
the rate of erosion, traps precious moisture and
changes the texture of the soil. Plants gain a foothold
more easily.
STOP
9
The final two stops lie along the Capitol Gorge
spur road, longer and more winding than Grand
Wash. Although a through road from 1884 to 1962,
the drive now ends about two miles from here.
The awesome narrows you will now enter is worn through
Wingate Sandstone, the same formation that forms
the sheer cliffs along the west face of Captiol
Reef and the towering walls of Grand Wash. For some,
Capitol Gorge is erosion's most dramatic handiwork
at Capitol Reef National Park.
The right fork of the road here leads to Pleasant
Creek, one of the few perennial streams in the park.
As wagonmasters did a century ago, carefully consider
the weather before you proceed into the gorge.
STOP
10
Soaring to your front left is an eroded layer
of sandstone that, like the Wingate, was once
desert sand. This sandstone is the Navajo Formation,
over 1,400 feet thick in places. Its white, rounded
domes inspired a name for Capitol Reef.
Many visitors notice that the Wingate and Navajo
- both formed from ancient deserts - seem to erode
differently. The Wingate tends to make sheer cliffs;
the Navajo rounded domes. Why?
Part of the answer lies in the rock layers upon
which these "petrified deserts" rest.
The Wingate lies on the soft beds of the Chinle
Formation. Because this softer rock erodes more
rapidly and undercuts the Wingate, the massive sandstone
often breaks away to form sheer cliffs.
By contast, the Navajo rests on the reddish rock
layer that forms the base of the canyon walls on
both side of you. This water-deposited sandstone
- the Kayenta Formation - provides a firm foundation.
The Navajo is undercut less often than the Wingate
and erodes away in smoother contours.
Incidently, the Kayenta lies just above the Wingate
and just below the Navajo Formation. It is about
350 feet thick and 190 million years old.
STOP
11
Perhaps
it is fitting to end your tour here, deep within
Capitol Gorge. All around in soaring summation
rest elements of the Capitol Reef geologic story.
Dune lines in Navajo Sandstone walls whisper of
the ancient landscapes and sediments that became
rock. Rounded domes and deep canyons proclaim eloquently
the power of erosion. And the rapid changing of
rock layers along the fairly level Capitol Gorge
spur road testifies to the tilting and bending of
the Waterpocket Fold.
A
short stroll down the canyon takes you by the vandalized
remains of some ancient rock art or petroglyphs.
American Indian farmers of the Fremont Culture cultivated
their crops along the streams of Capitol Reef until
about 1300 A.D. Their most puzzling legacy may be
rock art.
In
1884 it took Mormon pioneers eight days to clear
the first road through the Gorge, and settlers had
to remove heavy debris after every flash flood.
When Utah Hwy 24 was opened in 1962, the road was
closed. Early travelers recorded their passage on
the canyon walls at the Pioneer Register.
You
will end your walk at The Tanks, where erosion has
carved pockets in the rock that often hold rainwater.
Perhaps your journey down the Scenic Drive - and
through the rock formation of ages - has helped
you know better a scenic grandure that often leaves
newcomers awed.
And sometimes - forever possessed.