The Hike to the Cache
The first supplemental waypoint is at the west end of the Kron
House parking lot. There is a gray pipe barrier over the road, and
the road itself was once the entrance road to the park. This is the
start point for the hike.
The second supplemental waypoint is where you will make a 90º
turn to the left to walk along a small bottoms area, go uphill,
pass a dam/pond, and continue up to close to the cache location. Be
advised that this is a steep hill, and leaves during most of the
year make the old roadway quite slippery in places, and they
obscure some rocks, roots, etc, underneath. Take your time and
enjoy the scenery, stopping for some air if necessary. There are no
heroes going uphill.
Once at the cache location, the mountain you are standing on is
Hattaway Mountain. Sugarloaf Mountain is to the southeast, at
~150º, and Morrow Mountain is to the south-southwest, at ~210º.
Morrow Mountain is the highest "peak" in the Uwharrie
Mountains.
Geological Background
If the three hills you can see (including the one you're
standing on) could talk, they would tell an amazing story of forced
separation from their place of birth, millions of years of
wandering the ocean, periods of extensive volcanic activity, burial
under miles of rock and subjection to many hundreds of degrees of
heat and awful pressure, and finally, rising up and having to
suffer the indignity of eroding away to a small, seemingly
non-descript "mountain".
Over 550 million years ago (Ma), parts of what would become
Africa, South America, and other southern continents, were joined
together in a huge continent geologists call Gondwana.
It was not a good time to live on the northwest corner of that
supercontinent. Active volcanism was depositing masses of ash and
rock over (and under) a broad oceanside area. Sedimentary deposits
of mud, clay, and silt were building up on the sea bottoms, also.
As the pyrotechnics continued, massive intrusions of a hard,
volcanic rock were squeezing up into the mudstones of the ocean
floor.
These volcanic rocks are often called "rhyolite", but have more
iron and magnesium in them than rhyolite -- but not as much as in a
heavier rock called "dacite". Splitting the difference, the correct
term for these hard, resistant rocks is "rhyodacite".
It is possible that the volcanic activity in northwest Gondwana
was due to the beginnings of a process whereby a chunk of the
continent (refered to as "Carolinia" by geologists) broke off and
began to recede from it. In fact, this eventually did occur, but
the date is hard to pin down. Current estimates vary widely, but we
will consider 530 Ma as a probable date. This date has been
very recently established by Dr. Jeff Pollock in his 2007 doctoral
dissertation.
Over time, the ocean began to shrink and what are today Africa
and North America drew closer, with Carolinia in between. About 450
Ma, after some 80 million years of being a separate micro-continent
drifting across the ocean, Carolinia was joined to North
America.
Between 300-250 Ma, Africa and North America collided, forming a
super continent. The collision raised mighty, Himalyas-like
mountains, and the remains of those mountains are today's
Appalachians. During this period, Carolinia's rocks were
buried deep within the earth, and exposed to high pressure and
temperature, which slightly changed their appearance and
structure.
By 220 Ma, the super continent once again split apart, with the
spreading, new Atlantic Ocean between North America and Africa.
Ever since about 250 Ma, everything east of the Tennessee
plateau has been eroding away to. Many thousands of feet of
vertical erosion have exposed the insides of the ancient,
half-billion-year-old mountains. These remains are what you stand
upon and see before you.
Wouldn't you agree that after such a long and difficult history,
these three old-timers look pretty good?
-----------------------------------------------------
Note: While there is mostly general agreement about the sequence
of events outlined above, there is considerable debate within
professional geological circles about the timing of these events.
Recent publications by workers at North Carolina State University
and other institutions have helped narrow the timeframes.
-----------------------------------------------------
Logging requirements:
Send me an e-mail -- not part of your log --
responding to the following:
1. Make the subject of the e-mail "GC1KKKM, Three Beautiful
Old-Timers"
2. How many people are in your party?
3. Over millions of years, rocks within Carolinia were "built"
by sedimentation near sea level, sedimentation far below sea level,
and solidification of magma within volcanoes. All were mostly
lightly changed during various times during the past several
hundred million years. Today, you see the remains of the magma
within volcanoes (the mountains you can stand on and see), but few
sedimentary rocks.
a. What happened to all the
sedimentary rocks?
b. And, why did that
happen?
4. When Africa and North America collided 300-250 Ma, the rocks
within Carolinia were altered. What is the geological term for
altered rocks, and what does the term literally mean?
-----------------------------------------------------
References:
Bradley, P. Piedmont Geologist, North Carolina Geological
Survey. Personal correspondence, 2009.
Hibbard, J., et al. "Links between Carolinia, Avalonia, and
Ganderia" in the Appalachian peri-Gondwanan Realm. Geological
Society Special Paper, 2007.
Meldahl, K. Hard Road West. University of Chicago Press,
2007.
Pollock, J. "The Neoproterozoic-Early Paleozoic Tectonic
Evolution of the Peri-Gondwanan Margin of the Appalachian Orogen:
An Integrated Geochronolocial, Geochemical and Isotopic Study from
North Carolina and Newfoundland." Unpublished PhD Thesis, North
Carolina State University, 2007.
Tarbuck, J, and Lutgens, F. Earth: An Introduction to
Physical Geology. Pearson Prentice Hall, 2005.
Platinum EarthCache Master