Lost Treasure in the Desert
a study of geology using GIS and ArcView
by Michelle Bergey, 3rd grade teacher, Twentynine Palms, CA
Setting the Stage
Map Showing Known Mines in Twentynine Palms
Map Showing Some Known Geology of Twentynine Palms
" The ore, he said, was enormously rich and there was enough in sight to make him wealthy beyond his fondest dreams. His description of the place would locate it either in the northeast corner of the Joshua Tree National (Park), or just across the line to the west. ...the next morning he packed up...no one ever saw or heard form him again."
- John D. Mitchell, Lost Mines and Buried Treasures Along the Old Frontier
What I envisioned was to look at the data that was available about the geology and topography of the area and known mines, and see if there was enough of a pattern to predict where one might find gold. Of course, one cannot just go out and prospect without permission of the property owner, and many mines are now on Joshua Tree National Park property. The project was just for fun, and to show students how you can look at maps, geology, and mineral attributes in a new and fun way by imagining yourself finding the next great gold mine!
Tips for Gold Hunters
The history of Twentynine Palms, California includes many stories of gold mining, some successful, others not. In fact, the name Twentynine Palms came into popular use around 1870 when used to describe a mining claim. Mining in the desert was not easy because there is not water easily available for panning. The method used in the desert is called Dry Washing.
- Students will be able to define the following geology terms: erosion, weathering, metamorphic, igneous, sedimentary, mineral, placer mining,
- Students will be able to explain the relationship between erosion and placer mining
- Students will be able to explain some of the properties of the mineral gold, and its uses in our society.
- Students will be able to describe some of the minerals that commonly occur in the presence of gold.
- Students will be able to discuss the history of mining in the area, why most efforts were unsuccessful, the environmental effects of mining.
- Students will be able to the identify the following features on a map: symbols, contour lines, differences in topography if noted, streams and rivers, roads, and be able to describe their locations and possible relationships.
- Using ArcView, students will be able to make themes active and inactive, pan, zoom, open a table, edit a table, and create and print a layout.
Knowing that gold is heavier than most minerals, some miners even used blankets to "dry wash". By bouncing sand up and down on a blanket, the wind would blow the lighter particles away, leaving heavier gold to settle on the blanket.
If you want to learn more about gold in California, go to this site that is maintained by the California Department of Mines and Geology: Gold in California
I found two good sources for digital maps. The easiest one to download from the internet was a raster map from www.esri.com. This map required no formatting for ARCVIEW, and it was fast, and only cost about $10. However, you must build all of your themes yourself, using the raster map as a base, almost like a picture.
Free maps are also available from USGS, but do require some conversion, and for a beginner might prove to be too frustrating. The advantage is that many themes like hydrology, elevation, and transportation are already built in, saving tons of field work and research.
Other potential sites for free maps are BLM, EPA, and many local government agencies.
Here is a great site that one of the other participants in our institute found that has a ton of links for sources of maps. (Thanks Gene!) Cool Map Sites
A teacher using ARCVIEW would be well advised to own the "schools and libraries" package that has much data and maps all ready to use for ARCVIEW.
Joshua Tree National Park
SETTING THE GEOLOGY/GEOGRAPHY STAGE:
Before students can really find any meaning in their quest for gold, they must be taught several basic geological properties and geography terms. First of all, different rocks contain different minerals, and different minerals do different things. Some are heavier, some are attracted by magnets, some conduct electricity, etc. They need to know that gold is heavier than quartz sand, and therefore will sink in water, or in relationship to sand.
Next they need to know about erosion, and how it affects rocks and mountains, and when and where does it occur.
In addition, the assumption could be made that students easily recognize features on a map such as symbols, contours, directions. Personally, I wouldn't make that assumption! These type of things should be reviewed using traditional maps that are available.
Obviously, this type of project would encompass many lessons over a long period of time, probably a semester or so, depending on the age of the students and their ability levels.
Once armed with a basic knowledge of these things, they can easily come to the conclusion that gold that originally might have been in a quartz vein, exposed to wind and rain, would break off and travel downward to stream beds, alluvial fans and bajadas, all common features of the desert landscape that is in their very own back yards! Cool!
I think that it would be interesting for the students to do some actual field work, using a gps to note things like elevation of known mines sites, vegetation patterns, stream beds, etc. Rainfall, while infrequent, does vary based upon elevation, and it might also be illuminating to look at varying rainfall with the area. These are themes that could be added to the project during the school year.
alluvial fans: During the summer months, intense rainstorms often produce flash flooding among many desert washes. These strong currents carry sand, gravel, and rock from higher elevations, depositing them into the valleys below. These deposits are called alluvial fans.
arroyos: desert washes
playas: lakes that occur in valleys that may contain water a few weeks a year during the rainy season.
pinto gneiss: (pronounced "nice") , a dark metamorphic rock. It is the oldest rock with Joshua Tree National Park, thought to be 1.5 billion years old.
monzogranite: an igneous rock that were once part of the molten masses which were forced upward into the overlying, older, pinto gneiss. Erosion over the ages has stripped away the pinto gneiss, exposing the monzogranite outcrops.
dikes: rocks that intrude into the monzogranite in bands. These dikes were formed when molten rock of a different texture intruded into cracks or joints in the already formed monzogranite.
weathering: is the term given to the processes which cause rocks to fragment and crack.
erosion: lifts up and carries away the rock damaged by weathering. The three main forms of erosion are wind, water, and ice. Running water, even in arid environments, is by far the most important erosional agent.
lode mining: Mining a deposit or vein containing quantities of a valuable mineral by digging a tunnel or sinking a shaft.
placer mining: Mining minerals that have eroded from surrounding mountains and hills into deposits of gravel or sand.
Petralia, Joseph, Gold! Gold!!, A beginner's Handbook and Recreational Guide: How and Where to Prospect for Gold, Sierra Outdoor Products Company, 1982
Joshua Tree National Park maps and publications
Trent, D.D., California Geology a Publication of the California Department of Conservation, Department of Mines and Geology
Klein, James, Dry Washing for Gold , Gem Guides Book Company, Baldwin Park, CA 1994
Mitchell, John D. , Lost Mines and Buried Treasures Along the Old Frontier, Rio Grande Press, New Mexico, 1995
Klein, James, Where to Find Gold in the Desert, Gem Guides Book Company, Baldwin Park, CA 1980
Miller, Ronald Dean, Mines of the High Desert, La Siesta Press, Glendale, CA 1968
Go Back to Intro
This project is under continuing construction!