|
Home|
Bangs Canyon Page
This hike will take you on a short trip to an abandoned mica mine.
We will be in a typical semi-desert shrubland ecosystem. The hike
starts from the Bangs Canyon Staging Area. Along the way we will
learn about the animals, plants, and trees that live in this zone.
Much of the hike follows a seasonal stream. Here we will be able
to compare the vegetation found in a riparian zone to that in the
surrounding area. We will also study the geology of this very diverse
region. We are taking our hike in early June. Ready? Let's go!
Bangs Canyon is located in Mesa County, Colorado, 8.2 miles (13.7
km) south of Grand Junction. The area is encompassed by the Gunnison
River on the northeast, the Colorado National Monument on the northwest,
Eastcreek to the southeast, and Glade Park to the southwest. To
get to the Area, take Grand Avenue from downtown Grand Junction.
Follow it across the Colorado River. After crossing the river, turn
left at the first stoplight. This is Monument Road, our route goes
immediately left again on D Rd. which turns into Rosevale Drive.
Follow Rosevale for 1.2 miles (2 km) to a "No Outlet"
sign where Little Park Road proceeds to the right. Follow Little
Park Road 5.5 miles (9.2 km) to the Bangs Canyon Staging Area.
 The
road climbs up towards the height of the Colorado Plateau and provides
excellent views of the Grand Valley and across Billings Canyon to
the Colorado National Monument. Bangs Canyon is to your left; follow
the gravel road the short distance to the parking lot of the staging
area.
The Bangs Canyon area is located at 6,144 ft (1,932 m) in elevation.
It is very typical of the high desert canyon country of western
Colorado and eastern Utah. Before we start the hike, notice the
large hill behind the parking area. The rocks deposited here belong
to the Morrison Formation.
 The
Morrison Formation was deposited in a large lake during the Jurassic
Period. Dinosaur fossils found in the Morrison are abundant in the
Grand Junction area. The Morrison is composed of swelling clays
that when wet can expand up to 6% beyond their dry volume. This
unusual characteristic allows the clays in the Morrison to be used
to line landfills and ponds to prevent seepage of the water, but
it also causes problems for the houses built on top of it in places
like the Redlands. When the clays expand and contract, foundations
become unstable and may crack. The greenish red color of the hill
is typical of the Morrison and is a good indicator for the formation.
From the parking lot, a gravel road continues into Bangs Canyon.
Our route follows the foot trail. Pass through the stile in the
fence and we are on our way. The path goes downhill for 0.2 miles
(0.33 km).
 
We are in a typical semidesert shrubland ecosystem. There are six
vegetative types in Bangs Canyon: pinon-juniper, sagebrush, saltbush,
mountain shrub, conifer, and
riparian
vegetation. Initially you will see a pinon-juniper, which is the
largest type of vegetation and includes Pinon
pine and Utah
juniper. The understory
of these two trees consists ofIndian rice grass, galleta grass,
western wheatgrass, and Colorado wildrye. Sagebrush is found among
the pinon-juniper and at lower elevations. Big
Sagebrush is the most dominant shrub, however you will also
see Rabbitbrush,
and Gambel Oak.
The understory of the sage is covered with numerous grasses,
including Sedge, galleta grass, Indian
rice grass, blue grama, western wheatgrass, and crested
wheatgrass. At this time of year we also see many of the desert
plants in bloom including Indian Paintbrush,
Yellow
Sweet Clover, Penstemon,
and Yellow Salsify. While these are pretty to see, please
stay on the trail to avoid damage to another unique feature found
in a high desert ecosystem, cryptobiotic
soil. This is the black crust you find in areas off the trail
and is very important to the vegetation in the area. Cryptobiotic
soil is formed from blue-green algae that winds its way through
sand grains  and
binds them together keeping the sand in place and preventing erosion.
It also holds negatively charged clay minerals that attract positively
charged cations such as potassium and calcium that are nutrients
that plants need. These soils are capable of holding onto desperately
needed water long after rainstorms allowing the plants to take up
more water. So as you can see these microscopic plants play a gigantic
role in the health of the desert ecosystem. These soils are also
very fragile, it can take anywhere from 50-250 years for crytobiotic
soil to recover from the damage caused by one footstep so please
take care to stay on trails or bare rock whenever possible.
 After
passing down a series of "stairsteps" eroded into the
Jurassic Entrada sandstone, which is an example of
sedimentary rock, we
come to a flat area and a split in the trail.
The left trail goes deeper into Bangs Canyon. Our path follows
the right trail that continues along a streambed. Early in the spring,
this stream is flowing from the snowmelt higher on the Colorado
Plateau. In most years by early June, only isolated ponds are left.
These ponds provide important habitat for aquatic creatures. We
will explore one of these farther down the trail. Notice also the
change in vegetation. Because of the availability of water, we see
new types of trees growing. Along the stream we find
 Cottonwood,
Willows,
Greasewood, andTamarisk
(Saltcedar). Notice that the leaves of these trees
are larger than those of the pinon pine and junipers. Trees loose
water through their leaves, a process called transpiration.
Trees in the desert conserve moisture by having very small leaves.
They are also coated with a waxy cuticle that helps retain moisture.
In the riparian zone, water retention is not
as critical, and so the leaves can be larger.
Our trail follows an old road alongside the stream. The stream
has formed a canyon by eroding a path through the sandstone. The
sandstone in this area belongs to the Wingate Formation. The Wingate
Formation dates from the Jurassic Period and is over 200 million
years old. It is a major cliff-forming unit and was deposited in
an ancient desert setting, much like the Sahara Desert of today.
If you look closely, you can see evidence of the sand dunes from
this desert in the walls of the Wingate in the form of cross bedding.
This cross bedding is formed as large dunes migrate with the wind.
Sand will build up on top of the dune and then avalanche off the
other side leaving behind the evidence we see today of migrating
dunes.
 The
Wingate is tan colored but there are large areas that are stained
black and red by desert
varnish. Desert varnish is a phenomenon found on most sandstone
cliffs in the desert. It is made of iron and manganese oxides that
coat the surface of the rock. The origin of the iron and manganese
has been debated, but two theories have come to the forefront of
the research. The first theory is that the iron and manganese is
precipitating out of rainwater that flows over the cliffs during
storms. The second theory also involves water but in this theory
it is thought that iron and manganese rich clay minerals stick to
the wet surface during storms.
 We
have now come about 0.35 mi. (0.6 km) from the start of our hike.
As we walk along the path, pick out as many different types of plants
as you can. You should see trees, shrubs,
cactus, forbes,
and grasses.You
will also notice that there are many lizards running across the
trail or sunning themselves on the surrounding rocks. In a short
distance we can easily identify the Plateau Stripped Whiptail, the
Tree lizard, and the Side-blotched.
The trail meanders along the streambed and crosses it in several
spots. Let's pick out a spot where there is a pool of water remaining
and stop for a rest.
 These
pools provide important habitat in this desert environment for aquatic
creatures. In just this one small pool, we see water
striders, tadpoles, andhorse hair worms. Around us butterflies
are everywhere: Weidmeyers Admiral, Swallowtails
as well as dragonfliesand
damselflies. In the walls of the canyon
are spider webs some of these are made by black
widow spiders. These spiders are part of the natural
balance in this ecosystem, but are very poisonous so study them
from afar.
In the mud surrounding the pools are numerous animal tracts. Look
closely and you might identify mice coyote, deer, and other rodents,
rabbits, skunks, ground squirrels, mountain lions, bobcat,
black bear, and fox, all are animals who make this high desert
ecosystem their home.
 After
traveling another 0.2mi (0.33 km), we see an interesting feature
in the canyon wall on the right. Here there are two very different
layers of rock with a distinct boundary between them.
The upper layer is the Wingate Formation we talked about earlier.
The bottom layer is the Chinle Formation, which was formed during
the Triassic period approximately 210-230 million years ago. The
Chinle is very red and composed of mudstone. This is our first clue
that the Chinle was formed from an aquatic environment, a mudflat
at the base of an alluvial
fan. If you look closely at the upper part of the Chinle, you
will see vertical white lines that terminate along the same layer
in the rock. These white lines are fossilized shrimp burrows. The
layer where these burrows end may represent an ancient water table.
Shrimp will burrow down to the water table in environments found
today so geologists think that the same thing was happening when
the Chinle was deposited.
The gray rocks that we see along the trail date from the Precambrian
period and are the basement rock in this area. They are metamorphic
rocks. Metamorphic rocks result from high temperatures and pressures
deep inside the Earth. If you look closely, you can see in these
rocks where they have been melted and folded.
The basement rocks along this trail are about 1.7 billion years
old and formed when two plates collided together to help form the
North American continent that we see today. After traveling another
0.2 mi. (0.33 km) along the trail look off to the left and right.
Can you pick out the boundary where the Chinle Formation meets the
Precambrian metamorphics? Look for where the black metamorphic rocks
meet the red Chinle.
Remember that the metamorphic rocks are 1.7 billion years old,
while the Chinle Formation is 250 million years old, this means
that we are missing 1.5 billion years of Earth history at this spot!
Geologists call this an unconformity,
but what is an unconformity? You can think of geologic history as
a book with each formation representing a chapter of the Earth's
history and someone has torn out 1.5 billion years of chapters from
the book for our area. This is a unique geologic feature of this
small western Colorado area where you are standing! What was the
fate of the rocks making up the 1.5 billion-year gap? The story
involves ancient mountainranges anderosion.
 In
the trail we are beginning to see numerous white rocks. These rocks
are quartz and are part of the waste
rock from the mine. Large waste rock piles are appearing on
either side of the trail also, a sure sign we are getting close
to the mine. At 0.9 mi. (1.5 km) the trail is solid white from the
quartz and forms a Y. Quartz is a mineral found in igneous
rocks.
 The
left path goes up steeply out of the canyon. Our path follows the
right trail and in a short distance we arrive at the mica mine.
At some time in the ancient past, a blob of molten rock intruded
a fracture in the Precambrian metamorphic rocks and crystallized
very slowly, forming a pegmatite
dike. Within this dike we find several different types of minerals
including mica, quartz, feldspar, garnet, and tourmaline.
Mica was mined here in the 1950s. The mica was used for various
things including insulation and windows. Looking out across the
creek from the mine, you can see another good view of the 1.5 billion-year
unconformity.
When you are ready, we can return to the staging area by the same
path.
We hope you have enjoyed our trip to the mica mine. It is a unique
area where you can learn a tremendous amount of biology and geology
in a very short distance. Let's go again sometime.
Bangs
Canyon Page
Bibliography
|
