Blue Ridge Country - January/February 2020 - 22
MOUNTAIN CURIOS
THE HEAVY-DUTY SCIENCE CURIO
New Eye
for
the
Blue Ridge
ANNE FULTON
We at Blue Ridge Country got a note in the email awhile back, about a new scientific study looking at "the electrical
conductivity of Earth's crust and mantle below the mountain chain," and such. We wanted to understand it better than we did
after several tries, so we contacted the study's lead author. He was kind enough to take it a bit toward better understanding
for the rest of us.
By BENJAMIN MURPHY
SHARP DROP: The falloff from the
mountains of South Carolina's Caesars Head
(foreground) and Table Rock (on the horizon)
state parks onto the Piedmont is starkly
illustrative of the unique character of the Blue
Ridge Escarpment.
INSET: Grandfather Mountain's Linn Cove
Viaduct is also a good place to appreciate the
escarpment.
22
BLUERIDGECOUNTRY.COM
A
lthough the last major tectonic event
to affect eastern North America ended
more than 100 million years ago, the
Southern Appalachian Mountains remain
surprisingly sharp and steep.
And because the conventional scientific
understanding of how topography evolves
over time would suggest that these mountains should be much broader and smoother,
geoscientists have for decades debated the
reasons for this unusually sharp contemporary relief. Our recent scientific study offers
a new take on this problem in the context
of the impressively sharp break at the southeastern edge of the range-the Blue Ridge
Escarpment.
This work, entitled "Insights into Intraplate Stresses and Geomorphology in the
Southeastern United States," by me (while
a PhD student at Oregon State University),
Lijun Liu (University of Illinois) and Gary
Egbert (Oregon State University), finds that
the steep escarpment between the Appalachians and the adjacent Piedmont could be
the result of zones of weakness within the
underlying crust.
How and why? Isostasy is the key. Isostasy
essentially describes the buoyancy of the
rigid crust sitting on top of the quasi-liquid
mantle. The physics of this are very much like
those that describe how one would float in
a pool on a pool float: the underlying liquid
pushes upwards and thereby supports the individual on the float.
A similar situation exists beneath the
Southern Appalachians; the mountains here
appear to be isostatically compensated,
meaning that they are buoyantly supported
by the Earth's underlying structure.
However, a traditional analysis of isostatic
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Blue Ridge Country - January/February 2020
Table of Contents for the Digital Edition of Blue Ridge Country - January/February 2020
Blue Ridge Country - January/February 2020 - Intro
Blue Ridge Country - January/February 2020 - Cover1
Blue Ridge Country - January/February 2020 - Cover2
Blue Ridge Country - January/February 2020 - 3
Blue Ridge Country - January/February 2020 - 4
Blue Ridge Country - January/February 2020 - 5
Blue Ridge Country - January/February 2020 - 6
Blue Ridge Country - January/February 2020 - 7
Blue Ridge Country - January/February 2020 - 8
Blue Ridge Country - January/February 2020 - 9
Blue Ridge Country - January/February 2020 - 10
Blue Ridge Country - January/February 2020 - 11
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Blue Ridge Country - January/February 2020 - 17
Blue Ridge Country - January/February 2020 - 18
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Blue Ridge Country - January/February 2020 - 20
Blue Ridge Country - January/February 2020 - 21
Blue Ridge Country - January/February 2020 - 22
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Blue Ridge Country - January/February 2020 - 24
Blue Ridge Country - January/February 2020 - 25
Blue Ridge Country - January/February 2020 - 26
Blue Ridge Country - January/February 2020 - 27
Blue Ridge Country - January/February 2020 - 28
Blue Ridge Country - January/February 2020 - 29
Blue Ridge Country - January/February 2020 - 30
Blue Ridge Country - January/February 2020 - 31
Blue Ridge Country - January/February 2020 - 32
Blue Ridge Country - January/February 2020 - 33
Blue Ridge Country - January/February 2020 - 34
Blue Ridge Country - January/February 2020 - 35
Blue Ridge Country - January/February 2020 - 36
Blue Ridge Country - January/February 2020 - 37
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Blue Ridge Country - January/February 2020 - 40
Blue Ridge Country - January/February 2020 - 41
Blue Ridge Country - January/February 2020 - 42
Blue Ridge Country - January/February 2020 - 43
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Blue Ridge Country - January/February 2020 - 47
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Blue Ridge Country - January/February 2020 - 49
Blue Ridge Country - January/February 2020 - 50
Blue Ridge Country - January/February 2020 - 51
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Blue Ridge Country - January/February 2020 - 54
Blue Ridge Country - January/February 2020 - 55
Blue Ridge Country - January/February 2020 - 56
Blue Ridge Country - January/February 2020 - 57
Blue Ridge Country - January/February 2020 - 58
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Blue Ridge Country - January/February 2020 - 60
Blue Ridge Country - January/February 2020 - 61
Blue Ridge Country - January/February 2020 - 62
Blue Ridge Country - January/February 2020 - 63
Blue Ridge Country - January/February 2020 - 64
Blue Ridge Country - January/February 2020 - 65
Blue Ridge Country - January/February 2020 - 66
Blue Ridge Country - January/February 2020 - Cover3
Blue Ridge Country - January/February 2020 - Cover4
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