The following coordinates will take you to a place where you can
park and begin your hike: N33 31.290 W111 58.431
The hike is of moderate difficulty and the posted coordinates will
take you to a place where you can take your picture to post.
We passed many 12-13 year-olds on the trail on the way up/down and
they seemed to be fine- even in the 96 degree weather. Most people
were wearing shorts and tennis shoes. I suggest you wear a hat and
sunscreen and, as always, bring more water than you think you
need.
Park hours are sunrise to sunset and it is busy on the
weekends.
It’s not hard to understand how Camelback Mountain got its name
when you see it (from the right direction) the first time. Ok- it
might be a little bit of a stretch, but no more so than visualizing
a feline in the constellation Leo.
You might not be in the habit of performing rock identification, so
you may not have noticed that the “head” of the camel looks a lot
different than the rest of the camel “from the neck down”. It is
this difference in rock types that leads us to the mystery at
hand.
The Unconformity
The location where the two different rock types meet is what
geologists call an “unconformity”. This is the point at which a
layer of rock above does not “conform” to the same kind of rock
that is directly below it (sometimes, layers of rocks can be tilted
up 90 degrees, and so “above” and “below” may not always be good
directions, but in this case they are).
At the posted coordinates for this cache, you will be at a place
where you can clearly see the differences between the two rock
types. Take a close look at the head. How is it different from the
rest of the body (which I’ll now refer to as the “hump”)? Are they
the same color? Are they the same texture? The “hump” is made up of
a rock known as granite, which you have probably heard of before.
Some people use slabs of polished granite for their kitchen
countertops. Granite forms from magma (liquid rock) that slowly
cooled and solidified under the surface of the earth. Geologists
classify granite as an “igneous intrusive” rock. So, if the rock
formed underground, why is it now above the surface? The answer is
twofold: erosion over vast amounts of time, coupled with geologic
activity that pushed the hump up through the surface so we can see
it as we do today. Scientists have located certain types of
elements within the “hump” that allow them to precisely date its
age. Scientists believe the age of the “hump” all the way up to the
underside of the “head” to be approximately ____ years old.
Let’s consider the “head” for a moment. Why does it look so
different? The camel’s “head” is made up of sedimentary rock.
Sedimentary rock is formed when other rocks are exposed to physical
and/or chemical processes that cause it to weather, or break down
from the original form. We see the results of weathering most often
as different sized “chunks” of rocks- boulders, gravel, sand and
dust, to name a few. When wind or water transport these chunks,
they are further eroded and begin to accumulate as layers of
sediment. Over time, these layers of sediment may be compacted by
the weight of the layers above them, resulting in the creation of a
sedimentary rock. If you study the “head” of the camel at a
distance, you will notice that it has very distinct layers that are
made up of different colored rock. These remaining layers are old
sediments that have since turned to rock and then eroded yet again,
so we can see them in a “side-view”. Again, these processes take
place over vast amounts of time. Scientists have dated the rocks in
the head to be about ____ years old. So here we have arrived at our
little mystery- How can the “head”, which is ____ years old, be
sitting directly on top of a “neck” that is ____ years old?!?
Logging the EarthCache
In order to log this cache, you must perform 3 tasks: There are
different kinds of unconformities. The first task you must complete
is to e-mail me the description of your assessment as to which type
of unconformity is below the camel’s head. You will base your
assessment upon research (library, internet, whatever) and a visit
to the location where an example of the unconformity exists.
The second task (remember- EarthCaches are supposed to make you
think and learn!) is for you to e-mail me the information that is
missing from the blanks in the narrative above. Two things
specifically- How old are the rocks that make up the “head”, and
how old are the rocks that make up the “hump” (rest of the
body)?
The third task you must perform is to go to Camelback Mountain
(the posted coords are in the vicinity of a place that shows the
exposed unconformity), and take a picture of you, with your GPS,
pointing out the unconformity. Post the pic with log- along with
the number of people in your group. DON’T post the answers in your
log- even if encrypted. Make sure your pic is clear and shows YOU,
your GPS, and the UNCONFORMITY. Three tasks completed means you can
log the cache find. Anything short and your log risks being
deleted.
Geology is a fun and interesting subject for me, and I enjoy
sharing it with others. I hope you enjoyed this opportunity to
learn more about “our” Camelback Mountain. As always, please stay
on marked trails, take only pictures and memories, and leave only
footprints. Practice CITO too!
Acknowledgments
I am sincerely grateful to Tim Merritt, Park Supervisor for the
City of Phoenix, for his permission to create and publish this
EarthCache.
Special thanks to Terry Baker for reviewing the content of this
EarthCache page for accuracy and guidance in creating this
EarthCache.
