How To Build A Gold Grabbing Trap Line
By: Marlene Affeld
“Sourdough Sam” a savvy old prospector I met Alaska, shared this knowledge with me and he swears, it works. “Build a gold trap line, pull it once a year and work the concentrates over the winter ~ Mother Nature does most of the work.” Sounds simple, however for this method to be productive, it requires research, planning, some basic, easy to locate supplies and a few hours of focused labor.
To install a trap line you must have access and control of the creek bed you plan to work, so this method it best implemented on your own claim. An effective, gold-grabbing trap line requires that you have an aggressive spring runoff and year-around flowing water. A trap line works best in a shallow creek or stream.
Research is the first and most important step in evaluating trap placement. A detailed topographic map is a helpful tool. Go to a local map or copy center and have the section of the creek you wish to work enlarged to a clear and workable map.
If a topographic map is unavailable, sketch one out yourself, showing landmarks, boulders and detail of the stream contours, then have it enlarged on durable map paper. Make note of outcroppings, gravel bars, boulders and exposed bedrock.
Be especially attentive to bedrock as it is a prime prospecting location. In gold bearing locations, gold, because of its weight, can penetrate silt, sand, roots, grass and gravel to settle directly on bedrock.
Evaluate the stream bank and make note of previous high water marks, undermined tree roots or other natural obstructions to water flow at both flood stage and during low water; add this information to your map. Pay attention to detail; the topography can change dramatically from spring to fall and from season to season.
Next add grid lines to mark off the area into workable test sections and number them. I like to work with less than 1 acre per grid section. On the original copy of your map, add any permanent landmarks or reference information.
I have my field maps laminated so that I can write on them with wipe-off markers and I later transfer any new data to the original reference map.
Reading The Creek
Gold is one of the heaviest metals with a specific gravity of 19.3 - to put it in perspective, gold is approximately twice as heavy as lead which has a gravity of 11. A lot of time and large volumes of water are required to move gold. Alluvial gold travels by being carried in the intense run off and spring flooding that periodically occurs. A productive gold bearing creek requires a good drop in elevation so that the elusive mineral is carried downstream by water action.
During spring run-off or after heavy thunderstorm activity, hike the stream and observe the water movement. Make notes on your map of where the water slows and where it is running the fastest. Make note of transition spots, where the water movement abruptly slows from turbulent to calm or calm to fast moving water. Boulders, dead falls or outcroppings that obstruct the flow of high water will cause the stream flow to slow down or creates a swirling vortex that allows gravels and the heavy sands and gold to drop.
At flood stage, estimate the depth of the creek and cut several lengths of fishing line to that approximate depth. On one end of each line affix a fish float or bobber. On the other end of each line attach lead weights or sinkers of various weights. Drop these test lines in the creek above the area you are evaluating and make note of where they settle. Locating the points on the creek where gold is likely to fall is an important step in plotting where you will deploy your trapline when the water in the creek is low. (Be sure to retrieve your floats and do not pollute the stream.)
Remember that over the course of thousands of years, the stream bed has relocated or changed course countless times. Look for old channels or diversions that would have had water in them during previous flood stages on the creek. Look for rounded river rock and rounded gravels up in the bank that have been exposed by previous water action. Some of the best gold bearing sands and gravels may be a considerable distance from where the stream now channels.
Test pan various spots on the creek that have merit. If you find black sand and some color, further testing is warranted. When testing a spot, always run a minimum four bucket test. (Four five-gallon buckets of classified material from a single source.) This material can then be run through a sluice box or high banker and the concentrates panned out.
It is helpful to number your tests - i.e. Grid Section No. 1 - Test One, or any method that helps you maintain a record and precise location of your evaluations. Mark the test spot on your map. In a notebook, describe the results; date, test number, volume of material processed, percentage of black sand in sample, description of any gold or color in your pan, etc. Describe the gravels - are they smooth or angular? These notes will be helpful in choosing locations for trap deployment or if you wish to bring in heavier equipment.
Fabricating and Installing Your Gold Trap Line
Miners moss sluice carpet is the preferred matting for gold recovery. The moss traps and holds gold inside loosely woven vinyl fibers which are easily cleaned to recover the black sand concentrates and your gold. Choose the thick type that is backed so the gold cannot work through. This product can be purchased online from a prospecting supply shop. If you are planning to install several traps, this may be a bit expensive - if so, you can use the cocoa-fiber mats and apply your own backing as described below.
Thick cocoa-fiber door mats (These can be purchased fairly reasonably if you can catch them on sale at your local hardware store - or research and find a source to purchase this material by the square yard.) These cocoa-fiber mats are commonly used as entryway matting, because they do a great job of grabbing and holding the dirt people track in on their shoes. As such, it's perfect for catching and holding the heavies as they flow down your sluice trap.
Construction Adhesive - The adhesive is used to seal the bottom of the cocoa-fiber to prevent the black sand and gold from working through the mat and escaping out of the bottom. I think that the product “Liquid Nails” works very well. Just spread it thickly on one side of the mat and allow to dry. This can be found at any hardware store. There are also spray-on products that are designed to prevent rugs from sliding about - repeated spray applications of this rubberized material will seal the back of your mat and still remain fairly flexible.
Plywood or metal material to build a sluice box configuration. Metal works best as wood tends to rot or warp when submerged in water.
This is the point in the story that Sam left me in the dark, he was gone in the morning, before the coffee was ready, so I can only piece together the rest of the instructions he gave me.
When sitting around the campfire, I had pressed him for more details, he turned to me with a twinkle in his eye and a sly grin and said, “You are a prospector darling, figure it out,”. He added, “trapping gold is kind of like fishing or huckleberry picking, I’ll give you some information, just to help out a friend, but I’m not telling you all my secrets”.
He did tell me that he built the traps to the configuration of the spot where he wanted to test. He roughly said, “Get to know your claim, mark your map, and keep accurate records” - label your samples, read the creek. Don’t be in such an all fired hurry, study the situation so that your hard work pays off.”
Sam further shared that he put his traps in place in the late fall, when the water was lowest and there wouldn’t be folks about to take note of what he was doing. He then pulled out the traps a year later, again when the water was lowest.
Sam said that some of his traps were just the simple cocoa mats, the bottom sealed and he had attached short rope handles on the corners to pull them out of the creek bed. These he mentioned he put in place by prying up a boulder or otherwise weighing them down with a bunch of large stones. Sometimes he poked holes in the corners and staked them with metal tent stakes or rebar. Others he made as a sluice box configurations, bolted the mat in place and secured them with chain and rebar to a tree or boulder. Be sure to accurately mark on your map where you install traps, the spring run off may change landmarks, and when buried in black sand, they will be hard to find. A GPS reading is a big help, or flag coordinates.
Sam did tell me that when he pulled the traps, it required a partner. The mats will be heavy with black sand, sometimes as much as a 80 pounds. He said to go down the creek with a large panning tub, your gold pan and tools and several 5 gallon buckets to haul the concentrates home. It helps to have an ATV or strong partner to carry the concentrates.
When you pull the mat, pull it straight up, so as not to spill the cons. Next, throughly wash out the trap in your panning tub and then pan down some of the materials to see if you have gold. If so, reset the trap in place for the next season, if not move it to another location.
I am hopefully that other prospectors that read this article, those with more experienced and inventive spirit than I, will add their suggestions, comments and knowledge.
I have been studying my claims and I intend to lay a trap line this fall, so all advice will be most appreciated.
Wishing you color in the bottom of your pan.