Sunday, May 27, 2012

May 19, 2012. The Hawthornes Travel To Bryce Canyon, Utah.

The Hawthornes left Cedar City, Utah,
and headed to Bryce Canyon.
Enjoy the scenery along the way.
I'll let you know when we get to Bryce.

Mr. Hawthorne cannot resist a roadside entrepreneur.

He stopped to buy pine nuts,
which I don't like.
These particular ones tasted like Pine Sol.
The gentleman was selling both buffalo and elk jerky
and Mr. Hawthorne bought alligator jerky.
In Utah.

I do not know the significance of the 
upturned boot and the glove.
But I have a bad feeling.

This is NOT Mr. Hawthorne.
Not that that thought ever crossed your collective minds.

These bright formations of Red Canyon
are largely limestone,
built from sediments of a lake
that covered this region 35-50 million years ago.
The pink, orange, and red tones come from oxidized iron
in the limestone - in other words, rust.
Color hues depend on the amount of iron in the rock.

Welcome to Red Canyon,
considered by many to be home to the most beautiful
natural scenery on the face of the earth.

In 1875, Mormon pioneer, Ebenezer Bryce,
 came to Paria Valley to live
and harvest plateau timber.
Neighbors began calling the canyon behind his home
Bryce Canyon.
Soon after 1900 people were coming to see the 
colorful geologic sights,
and the first accommodations were built along the rim
above Bryce's Canyon.

W.J. Humphrey, Powell National Forest Supervisor,
saw Red Canyon in 1915 for the first time.
By 1920, he was trying to protect the
canyon's scenic wonders.
In 1923, President Warren G. Harding
proclaimed part of the area as 
Bryce Canyon National Monument.
In 1924, legislation established the area
as Utah National Park,
but legislation provisions were not met until 1928,
when legislation was passed and changed
the name to Bryce Canyon National Park.

These Red Canyon Tunnels
serve as the entrance to Bryce Canyon.

There is one road in to Bryce Canyon,
which follows the rim for 18 miles.
Once in, you go out the same road.
All the overlooks are on the east side,
so we drove the 18 miles through,
then, on the way back,
stopped at the overlooks on the east side,
 for the stunning geological panoramas.

These shots are all on the west side going in.

Eighteen miles in,
we arrived at Rainbow Point.

Posters at Rainbow Point
explain a little about the geology of Bryce Canyon:

Once A Lake
About 60 million years ago,a large freshwater lake began to fill the low basin that covered most of southern Utah.  Over a period of millions of years, rivers and streams from surrounding mountains gradually filled this lake with clays, silts, and sands.  Calcium carbonate cemented these sediments together, forming the limestone layer 
from which Bryce Canyon has been carved.

A Period Of Uplift
About 16 million years ago the land in southern Utah began to rise.  A series of plateaus were uplifted along large cracks in the earth's crust called faults.  The Paunsaugunt Plateau, on which you are standing, rose from near sea level to 8000 feet.  To the east, the Aquarius Plateau moved 2000 feet higher than the Paunsaugunt Plateau.

Erosion By Water
Even as the plateaus rose, erosion began to wear them away.  The Paria River, a tributary of the Colorado River, began cutting northward in the landscape.  Gradually, through a process known as headward erosion, it carved out a broad valley between the Aquarius and Paunsaugunt Plateaus.  As erosion continues, the softer limestone on the eastern edge of the Paunsaugunt Plateau is washed away, leaving the many colored pinnacles, or hoodoos, of Bryce Canyon.

The Colors
The range of color in the limestone layers at Bryce Canyon seems almost endless.  Yet limestone in its pure state is basically white in color.  Small amounts of iron deposited with the limestone have oxidized, or rusted, to produce the yellows, oranges, reds, and browns.
Manganese oxides cause the blue and purple hues.  Constantly changing weather and light conditions also add variety to the canyon's colors.

Table Cliffs and Aquarius Plateau

The High Plateaus of Utah
Stairway to the Clouds

The Paunsaugunt Plateau, where you are standing, was once connected to the Aquarius Plateau, thirty miles across the valley.  When the entire Rocky Mountain region began rising 16 million years ago, north-south faults split the vast tableland into seven separate plateaus. (Though most uplift occurred in the unimaginably distant past, recent seismograph readings indicate minute but ongoing activity.)  Here at the southern end of the park the Paunsaugunt Plateau is 9105 feet above sea level, almost 2000 feet lower than the Aquarius.

"Of this vast region of unexcelled scenery in Utah and Arizona, Bryce Canyon National Park is but a short, narrow strip along the southeastern rim of the Paunsaugunt Plateau and this plateau is only one of the seven great tables that dominate the landscape of southern Utah."
- Herbert E. Gregory,
A Geologic and Geographic Sketch of 
Bryce Canyon National Park, 1940

Bryce Canyon is famous for its unique, rich, and complex geology.  During the Cretaceous Period, from roughly 144 million years ago to 65 million years ago, the rock formations at Bryce Canyon began to develop.  For 60 million years, the Cretaceous Seaway stretched from the Gulf of Mexico northward into this area of North America and opening into what is now the Arctic Ocean, basically separating North America in half into two large islands.  As the seaway repeatedly invaded and retreated, sediments of varying thicknesses and compositions were deposited.  As the seaway retreated to the southeast, it left sediments thousands of feet thick,  which became the oldest brown and gray rocks now exposed
at the park's lowest elevations and across Paria Valley.

During the Tertiary Period, between 55-35 million years ago, rivers and streams flowing from surrounding highlands, deposited iron-rich, limy sediments in an ancient freshwater lake system.  The sediments became the reddish-pink rocks that represent the Claron Formation, 
or the Pink Cliffs.  Sediments may start as debris eroded from land.  Water carries varying sizes of debris and can dissolve this debris chemically.  As water cools or slows, particles settle to the bottom, sorted by size and weight. The sediments lithify, that is, turn to rock, as the particles are cemented and bonded together.

Now before sediments can lithify, they must be trapped in a basin.  To make a basin, you first need to build mountains.  Backtrack 200 million years.  Earth's crust was crinkling throughout Nevada and into southern Canada.  A strong, dense Pacific seafloor had smashed into North America's weaker continental crust.  Over 120 million years, compressional forces bent, folded, broke, and heaved earth's crust upward, giving birth to the Sevier Mountains.   Over millions of years, rain and snow acted like geologic jackhammers, splitting mountains apart,  From the mountains, streams and rivers carried debris eastward, pulverizing the boulders to mud in transit.

About 65 million years ago, before the dinosaurs went extinct, land in the Western United States changed dramatically.  The oceanic plate pushed up the continental plate, surfing atop the mantle instead of sinking and melting.  This attempt at escaping uplifted land, forming the Rocky Mountains and warping Utah and Arizona.  The continued slow uplift shaped a land-locked basin between the Sevier Mountains and the younger Rocky Mountains.  When the rivers wearing down the Sevier Mountains reached this basin, they deposited layers of mud and silts, and, at the lowest levels, formed ponds and lakes. Water escaped through evaporation and, with no rivers flowing out, the sediment was trapped.  Between 55-30 million years ago this mammoth mud puddle, known as the Claron Basin, continued to fill with sediments rich in calcium carbonate or dissolved limestone.

The Claron Formation consists of two types of limestone - a lower pink layer and an upper white layer.  In the early years of the basin, the environment was apparently more marsh-like, and plant roots helped oxidize iron to give the sediments a red color.

Bryce Canyon consists of a series of amphitheaters.  The erosional force of frost-wedging and the dissolving power of rainwater have shaped the colorful limestone rock of the
 Claron Formation into bizarre shapes, including slot canyons, windows, fins,
 and spires called "hoodoos."

  Water erodes rock both chemically and mechanically.  Scouring, abrading, and gullying occur when fast-moving water scrapes its silt, gravel, and rock debris against the firmer bedrock.  Slower moving  or standing water enters tiny rock pores, dissolving the cements holding the rock together.  Loose grains then wash away.  Along the plateau's rim, conditions are ideal for erosion.  Steep slopes increase the water's speed and energy.  Faults and joints caused by ancient compressional forces influence erosion patterns.  Freezing and thawing loosen the surfaces of slopes.  Debris borne by the runoff scours softer rock and creates gullies.  Harder rock remain as fins.  As gullies widen into canyons, fins become exposed to more erosion at vertical cracks.  As freezing water expands within cracks, it peels off layers and carves out vertical hoodoos.

Technically, Bryce is not a canyon because canyons primarily are carved by flowing water.  Naturally acidic rainwater dissolves limestone, making the rounded edges of hoodoos, but the freezing and thawing of water does most of the sculpting at Bryce Canyon.

About 200 days a year, ice and snow melt during the day at Bryce and refreeze during the night.  When water turns to ice, it expands to approximately 110% of its original volume, exerting tremendous pressure on the rocks and forcing them apart from inside the cracks.  First attacking the fractures created during uplift and faulting, the rock is chiseled into broken remains.  Hard rains remove this debris, helping to reveal fins, the first step in hoodoo creation.  The second step in hoodoo formation occurs when frost-wedging cracks the fins, making holes called windows.  When the windows collapse, they create the rust painted pinnacles called hoodoos.

It's merely another step in water's endless process 
of destroying the rocks it created millions of years ago.

You can read here about the geologic formational process
from plateau to fins to windows to hoodoos.

The bottom right white hoodoo is called the "poodle."
Or close one eye.
Or both.
Or have a few drinks.

One of the Park Volunteers was explaining about the "poodle"
and how there was only one vantage point from which to see it.
I never saw it until I saw the picture I took of it.

And this was after seeing another picture of the "poodle":

Water has been the major force shaping the landscape here.
Wind has had little, if any, affect.
Weathering occurs when rain, snow, and ice
break the rock into smaller pieces.
Erosion occurs when running water washes away
weathered rock debris.
Spanning millions of years,
nature's relentless forces have shaped,
and will continue to shape,
the landscape here.

Mechanical weathering is the most important type
of weathering at Bryce Canyon.
About 2/3 of the year,
the temperature rises above freezing during theday
and drops below freezing at night.
During these repeating freeze and thaw  cycles,
water seeps into the cracks in the rock,
expands as it freezes, and breaks the rock.

Chemical weathering also helps break down
the rocks at Bryce Canyon.
Water picks up acids from the air and soil,
dissolving the calcium carbonate cement,
which holds the clay, silt, and sand particles together.
These particles then fall away,
helping in a small way to shape the formations.

Looks like faces.

Example of fins.

A hoodoo is a rock pinnacle left standing by the 
combined forces of weathering and erosion.
Bryce Canyon has thousands of hoodoos,
in all shapes, sizes, and colors.

This hoodoo looks like a face.

These hoodoos, columns of rock,
are protected from erosion by a harder caprock
called dolomite,
a unique form of limestone reinforced by magnesium.
Alternating hard and soft layers
erode at different rates,
a process known as differential erosion,
which causes the varied hoodoo shapes.
As the softer layers continue to erode,
the hoodoos will eventually collapse.

This is Natural Bridge - a misnomer.
Technically, this "bridge" is an arch.
Bridges are carved by rushing water.
More subtle forms of water have sculpted this opening.
This formation appears solid and enduring,
but appearance gives no clue to longevity.
The weather is constantly chipping away at the opening.
This arch may last hundreds or thousands of years,
but eventually the weather will take its toll.

The arch begins as a recess in a narrow limestone fin.  As moisture seeped into cracks, freezing and thawing combined with gravity and chemical weathering to erode the rock. Hollows may have developed on both sides of the wall, gradually deepening until the sky showed through.

Fins in the background.
Hoodoos in the foreground.

This is Bryce Amphitheater -
the largest natural amphitheater in the park.

I'm at the upper level now.

I'm going up to the top.
Don't know where Mr. Hawthorne is,
but I have a good idea.

Leaving Bryce Canyon.

1 comment:

Marilyn said...

Pretty and interesting.