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Why Join
Everyone has their own reasons for wanting to join a Rock Club
For many years we picked up material that looked interesting - some went into my tumbler - some were used in landscape
rocks - and the rest just set around. What to do with them? Then one evening my wife Lorrie, suggested we look into joining
the local rock club. Maybe they could help us decide if we wanted to get more serious with our material,
So - off to a meeting I went. When I entered, there was a person to greet me and have me sign-in as a guest. As I walked
around looking at the exhibits, shop machines, etc., several people said hello and asked if they could answer questions,
etc. It was a pleasure to find friendly folks! I don't remember what the program was that night but I did know I wanted
to join.
After joining, one of the first things we did was to sign up for a lapidary class. This would not only get us started
but, would also let us know if we wanted to start buying our own equipment. Well, the rest is history! We've got
tumblers, saws, wheels, buffers, grinders, etc. etc.!! Keeping an eye on the classisfied ads, shopping at rock shops
and checking out their used equipment for sale, attending auctions, and shopping with show dealers have all been
useful in finding the equipment we wanted.
Joining the Rock Club also brought several unforseen benefits - how often have you tried to find that spot that looked
so easy to find in the book - only to find yourself going around in circles knowing you must be close! Well, the Club
had field trips - led by someone who knew where to go - and, what to look for! We have gone on lots of field trips
with the Club!!
Another unforseen benefit, has been the potluck dinners. Most overnight field trips have a potluck on one of the
evenings. What great feasts! Also - there are normally several events each year at the Club House with potluck
dinners included (Show, Xmas party, etc.)
Another great benefit has been the Shop classes - not only lapidary classes, but silversmithing, casting, beading,
wire wrap, basket making, carving, and others have been offered over the years. This has not only been a great way
to learn the craft, but also to try it out before having to purchase a lot of equipment. Instructors provide their
time free, and you only pay a small fee to cover material and shop costs.
One of the best things about joining the Rock club has been the people. We've yet to find an unfriendly Rock Hound -
most have been more than helpful when we've asked for directions, and given their advice when we've had problems.
If you've thought about joining a Rock Club - and haven't - maybe some of the above will give you the final Push!
Hooked on Rockhounding,
John Peterson
Past President, Reno Gem & Mineral society
Perennial Show Chairman
August 2007
--O--
Plate Techtonics
The land masses of the earth were once one large continent. The spread comes about, as geological evidence proves, the
continents are actually large plates that are in motion and are drifting apart at the same rate for the last 100 m.y.
The direction of movement has changed over the years, but the motion continues to this day.
The contact, where the two plates come together, where one is compressed and one is destroyed; this is called the area of
compression. The Pacific plate, for example is moving east into the American plate and then going under it eventually
being melted by the heat of the earth. This action causes the mountain ranges to rise (satelite informtion shows the
Sierras rising up to 1/2 inch per year.) That is also why volvanic action exists in the mountain ranges along the Pacific
Coast, the volcanoes from Chile to Indonesia continue to erupt in intervals.
Examples of the volcanic action near the edge of the plates: in Mexico City the volcano most currently active is Popocatpetl,
"The Prince", as well as Estlasiheualt, "The Sleeping Maiden". In New Mexicalli there is a dormant volcano, Cerro Piato.
In the U.S., Mammouth is expected to erupt in the near future (its last eruption about 700 years ago). Mt Lassen erupted 60+
yrs ago. Both Mt Shasta and Crater Lake, erupted in the not too distant past. Mt Saint Helens erupted 10+ years ago. And then
there is long dormant giant Mt. Ranier. The chain continues into Alaska around into Japan, then south into the Pacific Islands
to the Philippines (Mt Ebio), and the Island of Krakatoa, which was almost destroyed in 1883, with one of the largest
eruptions in modern history. The chain of volcanoes is called the ring of fire.
You will find volcanic action is found where one plate is being destroyed by colliding with another plate. The Pacific
Plate is going under the American Plate, causing the volcanic action and the rising of the mountain ranges along the Pacific
Coast (Sierra Nevada and the Cascades).
What is the cause of the movement of the plates? Several ideas have been suggested. The most current has to do with the
convection of heat through the mantel of the earth, and how it effects the motion of the plates in two different ways.
1. The drag of the lithosphere in the direction of the heat flow;
2. Distortion of the surface of the earth and causing the rise of mountains, the gravity acts to pull the plates downward.
If Lithoshere (land mass) is thick enough, and the gravitational force is greater than the viscous stress (pressure of
the magma) on the base of the plate, then the plate is pulled down into the magma. This forces the plate to move away
from the joint in the plates, this dragging effect moves the plate downward to be melted again in the core of the earth,
and also opens up cracks or weak points allowing magma to escape to the surface causing valcones and causing great stress
to cause earthquakes.
All of these forces are occuring along the coast of Southern California where the Juan de Fuca Ridge at the southern
end of the San Andreas Fault (the Gulf of Mexico) has been and continues to spread at a rate of about 1/4 inch a
year. Someday, Los Angeles will not be on the main land of California, but off the coast; like Baja California is off
the coast of Mexico. This action also causes the earthquakes along the San Andreas fault in California and is the
reason for most of the earthquakes in Nevada. Likewise, this plate movement is the reason for the volcanic action
we see in California and in the past,in Nevada.
D. W. Varnum
B. S. in Mining Engineering
B. S. in Geology
B. S. in Paleontology
September, 2004
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