The Rocker Box Blog Archive |
How to Read a River - Part 2 My 2 cents
As discussed in Part 1, gold is heavy, and it takes a lot of force
to move it. Gravity will always force gold to drop to the bottom of
whatever location it is in, until it reaches something that it
cannot penetrate…bedrock!
Bedrock is the solid rock that is underlying loose deposits of soil or alluvium (deposits of clays, sand, silt, and gravels). Bedrock is the foundation of mountains. Bedrock was laid down untold millions of years ago by volcanic activity, or pressed in solidity by eons of heat and pressure from ocean bottoms. The bottom line is that bedrock is sold, and once reached, gold can go no further, unless…
Bedrock is solid, but not flat. Bedrock has contour. Bedrock has cracks, fissures, faults, and “contact zones” (where two different types of rock join). Millions of years of seismic activity and erosion have shaped the landscape into what it is today. Earth movements have broken bedrock and moved it this way or that, up or down. Water has cut through to make valleys and canyons. But, you can still see evidence of bedrock.
Unless you are a hard rock miner (going after ‘lode gold” that is still encased in its bedrock (matrix), you are going to have to penetrate through the “overburden” (alluvial) to get to bedrock. So, it would seem that a good tactic to save time (and a whole lot of energy and expense) is to find where bedrock is either exposed or shallow.
Take a look at a typical river. Anywhere there are rapids, you have a location of shallow bedrock. It could be that a contact zone and/or seismic activity has caused a break in the bedrock, and you have a ‘stairstep” (severe drop). Boulders moved by high water pressure were ‘dropped” when the water pressure suddenly dropped because of the underwater topography. That same drop in water pressure will also cause gold pockets to form.
The problem is getting to those pockets safely, without endangering yourself by moving boulders or fast-moving water. It may be that specific locations are accessible for the dredger or the sluicer, or even panning along the bank or gravel bars may be fruitful. It may also be that waiting until the lowest water level during the dry season will provide good access.
If your river is flowing down a fairly steep canyon, take a look at the canyon walls. Do you see a place on both sides of the canyon where bedrock is exposed (such as an outcropping cliffs)? Draw an imaginary line between these two features, and where that line crosses the river is the shallowest point for bedrock. Notice I said, “shallowest point.” Shallowest point does not necessarily mean shallow to the point of easy access. Investigate this point further and look for bedrock outcroppings on the bank. Once again, the dry season is going to provide best access.
OK…now we’ve found bedrock at a location that we can access without too much difficulty. What condition is the bedrock in? If it is smooth and solid, you’d probably be best to pass it by. When water pressure is high enough to move gold, it going to push it over smooth bedrock without much resistance. But, always look for points in the flow that would drop the water pressure.
If, however, the bedrock is “craggy,” broken, or has cracks and crevices, that’s a VERY good sign, and you should do a “test” to see if gold is present. You will be amazed at how much gold (and big gold at that) that can fall into even the smallest of cracks and collect into a small pocket. It is well worth your time to open up those cracks (there are hammers and chisels for this, and there’s even a “slide hammer with a chisel point specifically made for this) and clean out those cracks COMPLETELY! Use a variety of metal hooks, spoons, grabs, brushes, and any other tool you have, to clean them out to the very bottom. Collect the concentrates into a gold pan and pan it out. If you find gold…stay and have some fun. If you don’t, survey the area and imagine the water at flood stage and look for paths of high and low water pressures…. then retest at another likely location.
The information in the above coupled with the information in Part 1 provides you with sufficient information to read a river to find bedrock and to local probable location for gold pockets. So, it’s time for you to take this info and find your glory hole!
Full Disclosure: The supplies, equipment, tips, techniques, and procedures I recommend are based on my evaluation and experience. I link items I recommend to companies I have an affiliate agreement with (or to The Rocker Box Catalog) from which I receive a small percentage of sales if sales are made during your visit to their website. The recommendations are mine, and mine alone. I use any proceeds to pay for The Rocker Box website, and to generate future articles and activities. I thank you in advance for your patronage and support to further the great recreations, hobbies, and vocations of treasure hunting, gold prospecting, metal detecting, ghost town hunting, and rock hounding.30-Second Bio: I am a retired soldier of the US Army Special Forces (aka Green Berets), serving for over 25 years. My specialties were communications, medicine, operations and intelligence, with extensive cross training in weapons and demolitions. I was a paratrooper, jumpmaster, combat diver, combat dive supervisor, combat dive medic, sniper, and pathfinder. I’ve been deployed countless times to locations on four continents, and have participated in operations in open water, riverine, jungle, mountain, desert, arctic, and urban environments…but I’ve been a “treasure Hunter” since I was eight. The End. |