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Title: Sand Dunes Story
Author: Bessken, Donna P.
Language: English
As this book started as an ASCII text book there are no pictures available.
Copyright Status: Not copyrighted in the United States. If you live elsewhere check the laws of your country before downloading this ebook. See comments about copyright issues at end of book.

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                            Sand Dunes Story


                                                        DONNA P. BESSKEN

    [Illustration: Map]

  To Scotty’s Castle
  Grapevine Mts.
  To Beatty
  Death Valley Buttes
  Funeral Mts.
  Cottonwood Mts.
  Kit Fox Hills
  “Old” Stove Pipe Wells
  Picnic Area
  Tall Dunes
  Stove Pipe Wells
  Devil’s Cornfield
  Mosaic Canyon
  Salt Creek
  To Furnace Creek
  Tucki Mt.
  To Lone Pine


WELCOME!

What do YOU see as YOU look across the dunes? Piles of lifeless sand? A
giant sandbox? Each of us sees the dunes differently. We would like to
share the story of the Death Valley Sand Dunes with you. This booklet
provides answers to some of your questions about the origin, composition
and formation of the dunes. We will also look at the plants, and for
evidence of animals that make their home here.

The features discussed are near the edge of the dunes and all you need
is your curiosity to explore this fascinating place. A magnifying glass
or magnet may add to your enjoyment. Remember—the dunes can be hot in
spring and fall as well as in summer months. Be sure to carry water,
distance is deceiving, and a short stroll may become an extended walk.
Do you want to walk barefoot? Be careful around the bushes; thorns and
plant debris are hidden in the sand. Carry your shoes, your feet may get
tired, or the sand may become too hot. When you are in the shade, look
around to see if other creatures are sharing the same cool place. This
is home for such desert dwellers as lizards, kangaroo rats and
sidewinders.

There is no guided trail since wind can soon cover a trail with sand.
It’s easy to find your way around and can be fun to choose your own
route. Look behind you to get firmly in your mind which mountain feature
will be your landmark to guide you back to your vehicle.

To make the best use of this booklet, flip through it to locate topics
of interest. Read in sequence, or follow the order of your discoveries.
Use your senses to appreciate and explore the sand dunes more fully.
Pick up some sand occasionally and compare the texture, temperature and
other qualities to that found in other locations. Be alert for little
things—notice plants, sand ripples, animal burrows and tracks.

Let’s walk into the dunes a short distance and learn their secrets. To
form sand dunes, three things are needed: wind, sand, and a place for
the sand to collect. The story of the dunes involves interaction among
these factors and the plants and animals that make their homes in this
sea of sand.


WHY ARE THE DUNES HERE?

Are they limited to this section of the valley? Do they migrate? Answers
to these questions are in the winds.

    [Illustration: _Significant seasonal variations in wind patterns
    affect the dunes._]

Winter and summer bring winds from different directions; northerly in
winter and southerly in summer. Landforms influence crosswinds and
swirling wind currents (eddies). These crosswind and eddy patterns
result in decreased wind speed and cause the sand to drop out in the
same general area time after time. Seasonal variations in wind direction
help keep the sand in one area.

Between individual dunes, white salt deposits are often seen on the
surface of an old clay lakebed (playa). Here too, we see how tall the
dunes are because the sand is piled entirely on top of this playa.
Infrequent rains produce changes in the playa surface, and occasionally
gravel is washed into the area from nearby mountains. Because of the
clay content of the soil, rain water does not soak in quickly, but lies
in pools. As the pools evaporate, fresh deposits of salts and minerals
remain on the surface. Similar salt deposits throughout the valley to
the south minimize the amount of available blowing sand by cementing it
together.

Dunes in Death Valley consist of sand from local materials found in
nearby mountains. The primary source of this sand is believed to be the
Cottonwood Mountains to the west and northwest. Although the shapes and
patterns of individual dunes may vary daily or seasonally, the dune
field itself is relatively stable.

    [Illustration: {Dunes}]

Pick up some sand! Is it fine or coarse? Wet or dry? Warm or cold?
Notice the different colors. A magnet may help you separate particles,
and a magnifying glass will allow you to examine them more closely. Most
black particles are magnetite—most white ones are quartz. Other minerals
provide still different colors. The sand here is a product of weathering
by wind, rain and chemical changes—breaking blocks of rock (primarily
granite) from nearby mountains into particles small and light enough to
be carried by run-off and tossed around in the frequent desert winds.

    [Illustration: _Take a close look at sand grains._]


HOW ARE DUNES AND RIPPLES FORMED?

Each wind produces changes to the surface of the sand. It takes a 10 mph
(16 kph) wind to move fine, dry sand. During a sandstorm, it may seem as
if the sand is blowing thousands of feet into the air. Your view of the
distant mountains may be obscured. Don’t be fooled! The dunes are not
entirely airborne! What you see are dust particles being carried aloft
because they are smaller and lighter than sand grains. Seldom does
dune-sized sand itself rise more than 6 ft. (2 m) above the ground, it
is too heavy.

    [Illustration: {Ripples}]

    [Illustration: {Movement of sand grains}]

Actually, most sand travels within about 18 in. (46 cm) of the ground in
a jumping movement called saltation. A windborne grain bounces a short
distance before crashing into the sandy surface sending other grains
into flight. The process continues as the wind carries the new grains a
little farther, crashing them, in turn, into the surface and other
grains along the way. Sand grains too heavy to blow in the wind creep
along the surface of the sand, while smaller ones are truly airborne
above the dunes. As a consequence, the entire sand surface flows or
creeps along.

Have you been comparing the texture, size and color of sand in various
sections of the dunes? Some differences will be more obvious if you have
the chance to visit both the tall dunes by Highway 190 and the low ones
by the picnic area. The soft, fine sand by the picnic area is carried
farther by the wind than the coarser material found in the taller dunes.

Smaller grains move farther than large ones. As a result of this sorting
of sand grains by variable winds, the larger grains accumulate in small
ridges forming ripples. Size and shape of these formations are related
to specific interactions between sand and wind. The windward side of a
dune generally has more dramatic sculpturing. Examine an area with
interesting ripples. Wind speed, direction, duration, and the amount of
sand are important factors that have been measured and used to determine
the size and spacing of dune ripples. Just as these ripples form, the
dunes themselves respond to changes in each of these factors.

        { Speed               { Size
  WIND  { Duration    + SAND  { Uniformity = RIPPLE FORMATION
        { Direction           { Amount

    [Illustration: {Cross-section of dune}]

  SUMMIT
  ANGLE OF REPOSE
  SLIPFACE
  WINDWARD
  ANGLE OF REPOSE
  FOC
  34°

All dunes may be described by the above traits. Variations in shape and
size of individual dunes are determined by the mathematical values
applied to each of the traits mentioned in the discussion of ripple
formation. Another feature of interest is the dune shape. Among these
dunes you may find examples of this classic textbook model and its
variations.

    [Illustration: _Plants on the playa in between the dunes_]

Note that the downwind side of the dune, the slipface, is the steeper
one. Fine dry sand can only pile up so high before it breaks away and
slides down the slipface as an avalanche to rest at the more stable
angle of repose, about 34 degrees. We create miniature avalanches as we
walk along the crest of a steep dune.


WHAT PLANTS LIVE HERE?

Each area within the dunes has something different to offer. Low dunes
near the picnic area have more vegetation than the tall dunes near
Highway 190.

Plants, visible from the top of many dunes, help the dunes remain here
by stabilizing the sand with their branches and roots. You will see
different plants, depending on whether you are in the tall or low dunes.
You may find them in a different sequence from that used in this
booklet. By looking for different shades of green, you should find each
of the major shrubs and trees that live in the dunes. Use the diagrams
and photos to help identify those you see. Let’s take a closer look to
learn how they survive and how they relate to the story of the dunes.

Can you find a low bush which appears to have no leaves? The stems are
jointed and succulent (juicy) and vary in color from yellowish to bright
green, depending on the season. Pickleweed (_Allenrolfea occidentalis_),
is often found on top of low mounds of sand. Do the stems look like tiny
pickles joined end-to-end? During summer months, tiny, inconspicuous,
yellow flowers may be seen at the joints. With a magnifying glass, you
may see the miniature leaves.

    [Illustration: PICKLEWEED
    (_Allenrolfea occidentalis_)]

By reducing leaf size, the plant minimizes surface through which water
can be lost. Green stems assume the task of photosynthesis, normally
done by leaves, providing food for the plant of this arid environment.

Although the sand does not often appear wet, pickleweed suggests water
is not far below the surface. It requires a wet soil and can grow in
very salty areas. Watch for pickleweed near Badwater also.

Find a different shrub, gently rub a leaf and smell it. Does it smell
faintly like fish? Look at the leaf you have just rubbed. Did the
surface dust rub off to reveal a deeper shade of green? Does it have
fleshy leaves? If so, you have found the inkweed (_Suaeda torryana_). If
your shrub has a less noticeable smell, and perhaps rubber-like texture,
and if you did not easily remove the white chalky coating from the light
gray green leaves, it is saltbush. If your shrub has numerous tiny
spines, be careful, you may have found a Russian thistle (_Salsola
kali_) or tumbleweed, as it is also called. They are not native to Death
Valley, but have become established in certain areas.

    [Illustration: INKWEED
    (_Suaeda torryana_)]

Inkweed’s young succulent leaves and seeds were used for food by local
Shoshoni Indians. Stems and leaves were processed to make a black dye.
You may notice tiny balls of seeds at the very ends of some branches.
The green flowers are very inconspicuous.

    [Illustration: FOUR-WING SALTBUSH
    (_Atriplex canescens_)]

Saltbush is light green and its dry, flat leaves are covered with salt.
Roots remove salts from the soil and water, then the salt is deposited
on the outer surface of the leaves. Consequently, the whitened leaf
surfaces reflect sunlight, thereby reducing temperature and water loss.
There are male and female saltbushes. You may want to search for seeds
or flowers. Seeds on female bushes have four tiny wings which give it
the name—four-wing saltbush (_Atriplex canescens_). Seeds were used as
food by Shoshoni Indians.

On your way into the dunes did you notice any other plants? If not,
watch for them as you return to your vehicle. Remember, the kinds of
plants vary depending on your location in the dunes. The clumps of grass
near the picnic tables are alkali sacaton (_Sporobolis airoides_).
Approaching the tall dunes you may have seen large plants with small,
shiny, smooth, dark green leaves—the creosote bush (_Larrea
tridentata_). It has small yellow flowers, usually observed in
springtime. Later, small, fuzzy, white balls containing seeds grow on
its branches. The larger green or brown, walnut shaped growths on the
branches are galls formed in response to an insect invader (midge). If
you missed creosote bushes in the dunes, watch for them along the
roadsides—they are common.

    [Illustration: CREOSOTE BUSH
    (_Larrea tridentata_)]

Although the sand dunes seem dry, there is an underground reservoir
providing moisture and nutrients for vegetation. The crusty mud playa
acts as a cap and reduces evaporation of the underground water supply.
Nearby, at Salt Creek, the same water flows on the surface as a stream
during the winter and spring.

    [Illustration: MESQUITE
    (_Prosopis glandulosa_)]

Most plants grow in the hollows between the dunes where they receive
some protection from the wind and can reach water more easily. Yet, the
mesquite tree (_Prosopis glandulosa_), probably the largest plant in
sight, is often on top of the dunes. By slowing the wind with its
branches, the mesquite causes sand to pile up in mounds beneath it.
Sometimes sand completely covers a part of the tree causing branches to
die. The sand then blows away, exposing those dead branches. Look for an
example which illustrates this sand movement. Mesquite trees have
thorns, so be careful. The mesquite tree loses its small, delicate
leaves during winter. Its deep root system, growing 50-60 ft. (16-20 m)
into the ground to reach fresh water, helps the tree survive. Some
plants, such as saltbush, pickleweed, and mesquite seem incompatible
because of different mineral and water requirements. However, these
plants are able to live near each other because their roots are drawing
moisture and nutrients from different levels of the soil. For example,
in a rain forest, where the roots have ample water, most plant growth is
above ground where competition is for sunlight. Whereas in a desert,
where sunlight is abundant, competition for water is more critical. The
root system of desert plants are highly developed, and each plant will
find the optimum level in the soil suitable for its growth.

    [Illustration: _Mesquite tree: sand collector, food and shelter for
    animals and Shoshoni._]

Be careful not to trample the roots as you explore the mound of sand
near the mesquite tree—you may collapse a burrow—remember, you and the
animals may be sharing the same shade.

Mesquite trees are also special in that they produce an edible and
nutritious fruit. In late spring, tiny, yellow flower spikes hang from
the branches. These develop into yellow bean pods by late summer. Many
different animals use the beans for food. Mesquite beans were also a
major food source for the Shoshoni.


WHAT DID THE SHOSHONI DO HERE?

Shoshoni Indians have lived in Death Valley for many years—migrating to
the mountains for the hot summer months and returning to the valley for
the winter. Their movements were related to supplies of food and water
and influence of temperature. It is more likely that areas such as these
sand dunes were visited for food gathering rather than as a place of
residence. To survive in the desert, the Shoshoni had to learn which
plants to eat, where they grew and when to harvest them. They also
learned which animals were reliable food sources—where they could be
found in abundance and when they were active.

Use your imagination—how well could you survive in this wild area? Where
and how would you find water? Which plants and animals would you eat?


WHICH ANIMALS LIVE HERE?

    [Illustration: KANGAROO RAT]

    [Illustration: BURROW]

Guess which animal lives in which hole! How large is the entrance? The
size of the entrance suggests the size of the animal. How many other
openings are nearby? Often escape exits save rodents from predators. Are
there recent tracks nearby to indicate it is an active burrow, or is it
covered with sand and debris blown in by the wind?

Inside these burrows the temperature and living conditions are not as
extreme as those on the surface of the sand. Try digging a small hole in
the sand well away from bushes. How soon does the sand change as you
dig? Is it warmer or cooler or wetter? Beneath the surface the moderate
temperatures and increased moisture provide an escape from the intense
heat. Consequently, dune residents spend the day in their dens and are
active at night.

Kangaroo rats, for example, cannot tolerate heat and escape it by living
underground. Also they are active only at night. They are very efficient
water conservationists. Although water is essential to the kangaroo rat,
they rarely drink, but produce their own water from insects and dry
seeds they eat. They have no sweat glands, and excrete highly
concentrated wastes to minimize water loss.

These rodents are not related to kangaroos at all! Their name refers to
their hind legs which are highly developed for jumping.

Watch for their tracks—when a kangaroo rat is moving slowly, it drags
its tail which leaves a trail in the sand in conjunction with its foot
prints. When the rat moves quickly, its tail doesn’t drag. From clues
such as these we can determine whether the rat is running from a
predator or just leisurely looking for food. The entrances to their
burrows are about 4-5 in. (10-12 cm) in diameter and may be 3 ft. (1 m)
or more deep. Smaller rodents, such as pocket mice, have similar habits
but live in smaller burrows.

Lizards are more active during daylight hours. Even though they tolerate
higher temperatures than rodents, they would perish if they were
stranded in the open sun for an extended period of time. Notice how they
run from bush to bush, seeking the protective coolness as well as cover.
Lizards are cold-blooded animals, responding to temperatures around
them—cold, inactive—warm, active. In the winter months, there is very
little lizard activity. However, summer days with ground temperatures
reaching 200 degrees F. (92 degrees C.) or more are too hot for lizards,
and they must seek shelter. They eat plant material, insects and smaller
lizards, obtaining moisture from their food. They also conserve water by
excreting highly concentrated waste.

    [Illustration: LIZARDS]

Perhaps least observed, but most inquired about dunes dweller, is the
sidewinder. Have you seen evidence of this rattlesnake today? It moves
in a sidewise manner leaving a series of parallel, J-shaped tracks in
the sand.

By looping across the sand, the sidewinder reduces slippage over the
loose material and decreases the amount of body surface in contact with
the hot sand. Sidewinders are primarily active at night, and escape the
heat of the day under a bush or buried in the sand, exposing only the
small horn-like structures on their heads. They eat kangaroo rats, mice
and lizards.

Imagine the dunes as an ocean where all the sand is water and plants are
islands scattered about. Each island offers shelter and a food supply
for the animals. Everytime an animal leaves the security of an island it
takes a risk. In daylight, people may play in the sand, but at night the
dunes come alive with the real business of survival. Usually all we see
of this activity the following morning is the evidence—tracks. Some
tracks are easily identified—each tells a story. Use the diagrams to
determine which animals most recently crossed the sea of sand around
you.

    [Illustration: KIT FOX]

Coyotes come into the dunes for food. True opportunists, they eat
whatever is available—mice, kangaroo rats, rabbits, insects, mesquite
beans and many other things. Their tracks are difficult to distinguish
from those left by domestic dogs. Smaller dog-like tracks are left by
the kit fox. These small foxes have large ears and well padded feet.
They too feed on small rodents. Coyotes and kit foxes receive moisture
from their food and drink water at springs within their hunting range.
They avoid exposure to heat by being active at night and staying in dens
or shaded areas during the heat of the day.


                                 TRACKS

    [Illustration: COYOTE
    2¼ in.]

    [Illustration: KANGAROO RAT
    ¼ in.]

    [Illustration: BEETLE
    ¼ in.]

    [Illustration: RAVEN
    3½ in.]

    [Illustration: KIT FOX
    1¾ × 1⅞ in.]

    [Illustration: LIZARD
    2 to 3 in.]

    [Illustration: SIDEWINDER
    4 in.]

    [Illustration: JACKRABBIT]

Jackrabbits are not seen often in the dunes, although their tracks and
droppings are seen occasionally. They feed on plants, getting moisture
from their food rather than from distant springs. Large ears radiate
excess body heat and help cool the animal as it rests in shaded areas
during the hot day.

Have you seen any birds? Birds also leave tracks! The large bird tracks
here are generally left by ravens—big, black birds which eat almost
anything. In the spring and fall, some migrating birds stop briefly.
Shrikes, sparrows, kingbirds and blackbirds are among the visitors and
residents of the dunes. Insects and vegetation provide food and shelter
for them.

    [Illustration: BEETLE]

Have you seen any insects? Tracks resembling those of a tiny bulldozer
tell us where beetles have traveled. Shiny black circus beetles or
stinkbugs and gray snout beetles are often seen.

Since most activity in the dunes takes place at night, very little of
this action is observed. However, in the morning we can stroll in the
sand and unravel the secrets of the previous night. As you look at each
set of tracks, imagine what the animal looks like as it moves. How big
is it? How many feet does it have? Are the feet side by side as though
jumping like rodents or rabbits, or do they alternate as in the walking
or running motion of lizards? How far apart are the prints? Does the
animal drag its tail? Now, where do the tracks go? Follow some animal
tracks to see what interactions have taken place. The same animal may
leave different tracks on different sand surfaces or under difference
circumstances. Notice your own tracks as you walk, run, jump or sit in
loose or firm sand. Try it!

_In many respects these dunes are like any Other deposits of windblown
sand along the coast or in deserts. They reflect variations in the sand
supply and respond to particular wind patterns following the same basic,
natural principles. Several other National Parks and Monuments have sand
dunes of various sizes and composition. Death Valley dunes are not the
largest in the United States by any means! Here the dunes reach a height
of 80 ft. (24 m). They provide a visual change of pace with their soft
lines and shadows in contrast to the sharp, rugged mountain peaks around
them._


  Sand
    soft
      fine
  Easy to sift and mold.
  Once a solid block of rock now weathered very old.
  Blown by winds into dunes and features.
  Forming a hot dry home for desert creatures.
  Patterns of shadow and shade by tree and sand dune made.
  Walk
    touch
      explore
  Enjoy the dunes and come back once more.
                                                      Donna Paul Bessken

    [Illustration: {Dunes}]


We hope you have enjoyed this walking tour. As you continue to explore
Death Valley National Monument, contact any National Park Service
employee if you need information or assistance.

    [Illustration: NATIONAL PARK SERVICE]

                    U. S. DEPARTMENT OF THE INTERIOR
                         National Park Service

As the Nation’s principal conservation agency, the Department of the
Interior has basic responsibilities for water, fish, wildlife, mineral,
land, park and recreational resources. Indian and territorial affairs
are other major concerns of America’s “Department of Natural Resources.”
The Department works to assure the wisest choice in managing all our
resources so each will make its full contribution to a better United
States—now and in the future.

    [Illustration: Death Valley Natural History Association]

The Death Valley Natural History Association is a non-profit
organization pledged to aid in the preservation and interpretation of
the outstanding features of Death Valley National Monument.

                 FOR INFORMATION AND MEMBERSHIP CONTACT
                              Death Valley
                      Natural History Association
                              P.O. Box 188
                     Death Valley, California 92328

  CREDITS:
  TEXT: DONNA P. BESSKEN
  PHOTOGRAPHY: T. FORBES OSBORN
  EDITED BY: VIRGIL J. OLSON
  DRAWINGS: SYLVIA STOSSER
  DESIGN AND GRAPHICS:
        RUSS JOHNSON
        GEORGIA SUMMERS
  Chalfant Press

    [Illustration: {wraparound cover illustration}]



                          Transcriber’s Notes


—Silently corrected a few typos.

—Retained publication information from the printed edition: this eBook
  is public-domain in the country of publication.

—In the text versions only, text in italics is delimited by
  _underscores_.





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