Lately, I have been trying to devise
Earthcaches about geological subtopics, which in the past, confused
me, especially while doing other Earthcaches. Essentially, I need
things explained much simpler than a cut and paste, textbook
example of a specific geological concept. There is, of course,
nothing wrong with that, (in fact I use that process on this cache
page for definitions) but for me I require a much more reasoned and
well-modeled clarification with some hands-on activity to drive the
point home. This constructivist attitude is a learner-centered
approach to teaching, one that I fully subscribe to in the
classroom and in developing Earthcaches.
Geographical Area of
Interest:
Physiographic Provinces (New Jersey): Appalachian Highland: NJ
Highlands Region: Upper South Branch Raritan River Watershed
(Morris & Hunterdon Co.): Hacklebarney State Park. I always
wondered what this region was all about and became even more
curious when I learned that glaciers hang out here from time to
time.
Background:
Highlands: The
Highlands are part of the great green sweep of the Appalachians
that shadows the East Coast from Georgia to Maine. The Highlands
region stretches from eastern Pennsylvania through New Jersey and
New York to northwestern Connecticut, forming a vital linkage
between the Berkshires and the Blue Ridge Mountains.
Hacklebarney: The
freshwater Black River briskly cuts its way through rocky
Hacklebarney State Park, cascading around boulders in the
hemlock-lined ravine. Two tributaries, Rinehart and Trout Brooks,
also course their way through this glacial valley, feeding the
Black River.
Characteristics:
• Forested Ridges
• Glacial Valleys
• Igneous and Metamorphic Rock Formations
• Faulting, Folding & Tilting
Objective:
To identify an important feature of the Highlands Region of NJ,
specifically, glacial valleys by close examination via
fieldwork.
Important Definitions:
1. Permafrost - is soil at or below the
freezing point of water (0°C or 32°F) for two or more years. Ice is
not always present, as may be in the case of nonporous bedrock, but
it frequently occurs and it may be in amounts exceeding the
potential hydraulic saturation of the ground material.
2. Glacial Valley - stream valley that
has been glaciated, usually to a U-shaped cross section. U-shaped
valleys occur in many parts of the world and are characteristic
features of mountain glaciations. Glacial valleys tend to have a
parabolic shape.
3. Arctic Tundra - The word "tundra"
usually refers only to the areas where the subsoil is permafrost,
or permanently frozen soil.
4. Bedrock - It is not just a town, it
is also the native consolidated (organized) rock underlying the
Earth's surface. Above the bedrock is usually an area of broken and
weathered unconsolidated (not stratified or loosely arranged) rock
in the basal subsoil.
5. Precambrian - spans from the
formation of Earth around 4500 (million years ago) to the evolution
of abundant macroscopic hard-shelled animals, which marked the
beginning of the Cambrian Age.
Activity:
This activity is designed to understand and experience the effect
glacial advance and retreat can have on a region and to identify
some of the physical characteristics that can result. In this case,
you will walk down a trail less than a quarter mile from the
Hacklebarney Visitor Center and you will arrive at a waterfall on
the Trout Creek that tells an amazing story. You will be looking
around, examining some very old and very large rocks and getting a
fuller understanding of this specific area.
Okay, so here is what happened and why everything probably looks
the way it does. Look around, you can see the evidence.
1. Glaciers from the north, during one of 22 recorded ice ages,
once again begin to move downward toward this region. An
advancement of arctic temperatures and environment create a tundra
biome and as a result, the permafrosting of the soil occurs. Water
leaches into the bedrock under the soil and freezes. This is also
called a paraglacial feature.
2. With the retreat of the glaciers and the expansion and
retracting of the frozen water, the rock beneath the soil is broken
apart. A mixture of lifting and tilting and natural surface erosion
caused the Precambrian rock to be thrust to the surface and is what
you will see at ground zero. Yes, there was some serious earthquake
activity here at one time.
Some people believe a terminal moraine caused this but I
seriously disagree. I think this is just a typical result of
glacier climate landscape within the Highlands region in a very
unstable geologic area. Bottom line, these rocks are just too darn
uniform and similar to have been randomly pushed here by an
iceberg. They are all from the same bedrock.
3. This waterfall formed as a result of permafrost (look it up!)
above the ground. Look closely at the rocks that make up the
waterfall. Do you see the lines that run down the rocks in
geometric patterns? It kind of looks like a checkerboard, doesn’t
it? These rocks were once in the process of being broken. Run your
fingers over them and feel the grooves. Ice thawed and these
channels emerged that you now see. The problem is these rocks began
to break at the end of the permathaw so the process was never
completed.
As you scan the area, remember these rocks are millions of years
old. They were once part of the bedrock beneath the soil. They used
to be very uniform. Although faulting and other plate tectonic
activity brought these rocks to the surface, it was glacial
activity that broke the rock apart and formed this waterfall you
now see. Look at the angle of the rocks. I estimated the tilting to
be about 72 to 75 degrees. That took a lot of power to move these
rocks to a vertical resting position from their original horizontal
resting position!
FYI:
CCC or the Civil Conservation Corps back in the thirties during
Roosevelt Works Program are the ones responsible for making this
place accessible and hospitable with steps, bridges, fireplaces,
pavilions, trailside shelters and even water fountains.
How to claim this cache:
Any “found it” log will be immediately and unceremoniously deleted
if it does not contain the following:
1. A picture of YOU with the waterfall in the background. You will
have to carefully climb out there to get a good shot of yourself.
If you are unable to climb and shimmy out there, do the best you
can, no problem. SEE EXAMPLE
2. A picture of YOU in front of the Welcome/Visitor Center
(coordinates waypointed) SEE EXAMPLE
3. In your log, NOT an e-mail, I would like you to write at least
one DESCRIPTIVE paragraph describing exactly what you see at ground
zero. I would like you to use AT LEAST three words from the
important definitions section of this document in your descriptive
paragraph.
4. In an e-mail to me, explain why you think this is typical of an
area which has encountered freeze thaw action (permafrost).
Well, that’s it. I hope you learned something about glacial
activity within our NJ Highlands Region. Thanks for caching with
Math Teacher.