In 1494, a farmer's son, George, was born in what is now
Germany. He was a bright kid, and entered school -- a
priviledge few children then enjoyed. As was the custom of
the time, his school teachers bestowed upon him a Latinized version
of his name "Georgius", as well as a last name (last names were
seldom used back then) "Agricola". Georgius Agricola
translates into English as George Farmer. Agricola (as he was
universally called) went on to get the best education then
available, and gravitated towards mining and minerals as his life's
interests. He wrote a series of essays and books on the
subjects, culminating with his masterpiece "De Re
Metallica", which was published in the year he died, 1556.
This is a big book, and at least as far as I can determine, it
is the first modern text book ever published on any subject.
It has chapter after chapter dealing with specific subjects
concerning mining -- shafts, drainage machines, ore processing,
types of ores and minerals, etc., etc. Just as important, he spent
serious coin on having photos (well, actually, woodcut images --
photography was several hundred years away) as an integral part of
the book. When he described a type of drainage machine, there was a
woodcut image of it, and he certainly realized that a picture is
worth a thousand words; there are well over 250 woodcut images in
the book. For over 200 years, De Re Metallica was the
textbook every mine owner and operator swore by. It was,
unfortunately, written in Latin, which was no problem way back
when, but Latin was less and less known to German, French, Italian,
etc. readers as the decades went by.
Enter two seminal characters in the effort to construct an
appreciation of Agricola's contributions: Herbert and Lou
Hoover. Herbert Hoover was a mining engineer who would go on
to become the President of the United States. His wife, Lou
Henry Hoover, was a geologist and "amateur" Latin
scholar. The Hoovers embarked on a mission to translate
the book into English. To say that they accomplished
that would be a major understatement. Their translation,
accompanied by hundreds of notes (some of which are several pages
long), bring Agricola and his time to life. Indeed, the notes
not only delve into the geology of the subject matter, they
virtually construct the entire history of mining as a serious
pursuit up to the time of Agricola.
No one can study the history of mining without encountering
Agricola's De Re Metallica, which in English means "On the
Nature of Metals", but no one can understand it without the aid of
the Hoovers' translation. To distill -- but hugely
oversimplify -- Agricola's accomplishments, the Hoovers offer these
as two of Agricola's observations that are original and
fundamentally important to our understanding of geology:
1. Ore veins originated
after the rocks containing them.
2. Ores were deposited
from liquid solutions circulating in cracks in the original
rocks.
The little creek you're at is within the Gold Hill Fault Zone,
perhaps better referred to as the Gold Hill Shear Zone. The
zone is a few miles wide in most places, and it was the place where
the rocks on the east and west were moving in opposite directions.
That created shear that both presented the opportunity for
water and other "volatiles" to form and carry large quantities of
minerals, and also provided the sheared space (cracks and voids)
within which the minerals could percipitate out as the fluid
cooled. Those familiar quartz veins that we see
throughout the area, as Agricola would point out, were once part of
a liquid solution. Silicon, in the form of silicon dioxide,
comprises most of the mineral content of the veins here, but there
are other minerals and elements, as well: One happens to be
gold.
Gold is heavy -- really heavy. Slate, granite and
quartz have specific or "relative" gravities of about 2.6 - 2.8;
gold has a relative gravity of 19.3. A relative gravity of 1 means
that the object has the same weight -- or density -- as water;
therefore, gold is 19.3 times more dense than water, and over 7
times more dense and heavy as the common rocks in the
Piedmont. Now, imagine that it has rained hard, and the
little stream is brawling along, carrying lots of small rocks and
pebbles. A piece of granite the size of a marble would be
carried much further than a piece of gold of the same size, simply
because the gold weighs so much more.
The title of this EarthCache is "Agricola and the Prospectors".
He has taught us the geological source of the gold within the
Gold Hill Shear Zone, and we know that gold is so heavy that few
large pieces of it will travel far from its source in the
creek. Therefore, it's time for you to be an imaginary
prospector.
Other Educational Information:
Logging
Questions:
Send me an e-mail – not part of your log
– responding to the following:
1. Make the first line of the e-mail
“Agricola”.
2. How many people were in your party?
3. Imagine that the year is somewhere in the early to
mid 1830's. Gold has been found down at what's being called
Reed Gold Mine, and also up at Gold Hill. You are
standing somewhere between those two places, and you are also
standing in the Gold Hill shear zone. Of course, the bridge
is not here and the road is probably not here, but the stream is --
Little Buffalo Creek. You have been panning for gold,
and have been slowly moving upstream. As you've moved
upstream, you have been well rewarded, as there has been more and
more gold, and the flakes are getting bigger. Suddenly,
however, you pass a point beyond which you find absolutely no gold
whatsoever!
You are convinced there must be more gold to be had, so...
a. ...what should you do?
b. Why?
4. The creek is steeply northeast to southwest here.
a. Looking to the northeast,
would you employ your solution to #3 to the east or the west side
of the creek?
b. Why?
5. Optional: Please post a photo of you and
your GPS on the bridge.
Bibliography:
Agricola, Georgius. De Re
Metallica. Froben, Basil. 1556. As translated
into English by Hoover, Herbert, and Hoover, Lou Henry in 1912, and
reprinted and re-issued by Dover in 1950, and Kessinger
recently.
Lienhard,
John. "Engines of Ingenuity: Hoover and Agricola",
http://www.uh.edu/engines/epi139.htm. 1997.
Wikipedia. "Gold" and
"Relative Density". 2010.
Note: For other
EarthCaches in The Deconsolidators, the Gold Hill fault zone and
mining district, and the Uwharrie Mountains series, go
here.
Hints/Spoiler Info: