I've been gold prospecting for 11 years, mainly in the Bradshaw Mountains in Yavapai County, Arizona, where I found over 8 grams of placer.
Ancient Rivers of the Tertiary
During the Tertiary geologic period, the United States (and much of the world) was warmer and moister. Arizona rivers of gold were formed at the end of the tertiary period when cooling occurred and the tropical plant life changed to grassland and woodland.
It is argued that the ancient rivers of gold (most often in Yavapai county) were created in Arizona about 2,000,000 years ago at the end of the tertiary period. The rivers that ran during this period are referred to as the "Ancient Rivers of Gold". Since this article will refer mainly to Arizona (that is where I live and where I have prospected for 5 years), the main theme of the article will be Arizona ancient river characteristics.
Looking for Tertiary channels (old waterways) that may have carried placer gold is another way to find the coveted "yellow color." This period of Earth's creation is when there was a great deal of volcanic eruption. It was not unusual to find flows of 4000 feet while volcanic material could move up to sixty miles. Some gold has been found under thinner layers of volcanic rock.
Rivers and waterways generally flowed to the south during the geologic ancient days. With all of the violent activity during the Tertiary, including the building of mountain ranges in the west, the surface of the southwest United States changed. Afterwards, rivers tended to move to the west. But the curious thing is that with this eruptive activity, the old pathways of water were interrupted. In some cases, these paths were broken apart. It is possible for a now dry ancient waterway to pick up again miles away. They can be high up in the mountains and simply stop. I have seen old waterways on the side of hills and mountains in a distinct layer cobbled with stones that were the bed of an old waterway. Layers of gravel can also be seen or revealed after digging, as is the case in California. It is also true that gold may be hidden under volcanic flows. In central Arizona, the trail of waterways is on top of older "ancient remnants" from northeast to southwest.
What to Look For
One technique I like to use to find gold is to search for old waterways that cross a current waterway. Placer may be there. A current waterway refers to a newer waterway since the Tertiary period and can be dry. This is particularly helpful on club claims. I pay attention to the banks and the higher areas adjacent to the waterway. Because of the fact that the direction of river flows were changed, ancient waterways will sometimes cross a current wash or river.
It is also possible to discover ancient benches. A bench is a cut out on the side of an elevated area where water cut through sandstone or softer rock. When water hits harder rock, it does not wear away as much and at that point sticks out from the higher soft cut out material, thus appearing like a bench. If a bench was formed since the Tertiary geological time period, it is called a recent bench. These benches were a place where gold could be deposited after traveling along the waterway, or where gold wore away a lode from rain runoff and got trapped. These are rich places to discover placer. When investigating benches, it is important to be very careful. They can be precarious.
A Mind's Eye View of the End of the Cenozoic Era and Beginning of the Tertiary Period
Imagine yourself sitting on a boulder in a relatively flat area of central Arizona at the dawn of the Tertiary period. You hear a loud crack, not unlike an explosion of two cars colliding, but magnified many, many times.
As you look to the northeast of your location, you see smoke, steam, and gas (and smell of sulfur) and rock starts to climb from the ground. The areas around the cracked ground rise forming hills. The inclination of the desert at the foot of the mountain has increased dramatically. Motion ebbs and flows, but not the din.
The next day the mountain begins to project further. The same litany of changes occur in approximately the same way. The rock of the soon to be mountain continues to inch higher. Noise generates due to the tossing and twisting of rock under pressure, the smaller mammals which characterize the era starting to fly and squawk at the same time. You wonder what will be next? After many hours of this action, things begin to settle. Deciding to sleep behind a boulder because you have no where to go, you notice the sky is hazy. As the sun peeks up in the east, you have a fatalistic view of what the future will bring. A strange sense of peace overcomes as your conscience gives in to the fates. You are enjoying passively the spectacle before you due to your powerlessness to change any of the geologic upcoming events.
Later toward the beginning of the afternoon you hear more uproar. Now you hear a bit of a whistling, noise made from steam pressure as it blows by rock chasms and protrusions near the surface but under the ground, structures that did not exist 2 days before. Then there is the hiss of steam, not unlike that of an old locomotive venting at a water and wood stop in the 19th century. Then loud cracking and blasts as the earth shakes, and the mountain rises more to the sky. The area at the foot of the mountain continues to rise, and its inclination is approaching 45 degrees to its former level.
After several days of observation, the mountain is now hundreds of feet tall. Over the millennium the mountain would attain its 9000 foot elevation. After day 3 you no longer heard the rustle of flying birds and the shrieks of smaller mammals. All had cleared out not knowing in what direction to fly. But fly they must. In the distance you hear a very loud sound similar to the release of compressed air and a large cat's purr. A mammoth was searching for food.
One must assume that you already knew how to gather the organic food of the area. You are barely surviving, but the noises continue to occur off and on for a longgggggg..... time. The number of outbursts and the shaking of the land becoming less frequent.
Water that used to run across the terrain in a southerly direction in your particular locale has been interrupted by the mountain. You see that the river that existed now runs around the mountain on the west side. It intersects the old riverbed at a junction about 5 miles from the mountain. When it rains and the snow melts, the river gets water from the upstream river bed and the rain wash that comes down the side of the mountain.
You have some cause for celebration because the amplitude of events and the frequency are decreasing. If only you could hold out until the Earth rested. If only the water would remain on course? If only the animals would come back? If somehow the rains would be sufficient to keep the plant life sustained? Even though you had hoped that the odd sounds and tremors of the earth would stop, you grew very old, never seeing the terrestrial peace you had hoped for.
In your wildest imagination, you could not envisage that in millions of years, gold prospectors would be searching the tops of mountains and the intersections of new and old river flow for gold!
How Ancient Rivers of Gold Can Appear
The Tertiary Period is Often Called "The Age of Mammals"
- Where to Pan for Gold: Tips for the Amateur Prospector From a “Pro”
Every river in the world contains gold. However, some rivers contain so little gold that one could pan and sieve for years and not find even one small flake. The amateur prospector will not be able to determine whether gold is contained within an..
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2015 John R Wilsdon
MG Singh emge from Singapore on December 20, 2015:
A hub out of the ordinary. Interesting
John R Wilsdon (author) from Superior, Arizona on December 20, 2015:
Thanks for stopping by.
Jeanette Harris from 11996 Valley Falls Loop Spring Hill Florida, 34609 on December 20, 2015: