Highly Mineralized Soil and Ground Balancing
With so many features to learn and understand, choosing your first metal detector can be a daunting task. There are several things to consider with your first purchase such as budget, brand name, and coil type, just to name a few. One consideration that is commonly overlooked is the location where you plan to do most of your hunting.
Location, Location, Location
As the name implies, metal detectors are built to detect metals. But they also detect minerals, such as iron, in the ground which can produce sporadic false signalling. When there is a high enough concentration of those minerals, it can be too much for your detector to handle. Before you can even think about buying a new detector, you must understand whether the type of ground where you’ll be hunting is made up of high concentrations of minerals. Of course, metal detector manufacturers have recognized this as a major issue in some parts of the world and have created an advanced feature known as ground balance.
I will talk about the nuisances of ground balancing in a future post, but generally speaking, ground balance allows your detector to penetrate highly mineralized ground without loss of depth and sporadic false signaling. There are three major types of ground balancing: factory-set, manual, and automatic. In order to metal detect effectively in highly mineralized ground your detector must have at least a manual ground balance feature. Units like the Garrett AT Pro have both a manual and automatic ground balance feature, which is a great combination.
How the Land Lies
So, how do you find out if your area has high mineralization?
- Go local -Consult with a local metal detecting club and/or fellow detectorists in your area. Ask them what kind of detectors they use and to share their experiences.
- Do your research-Analyze geological records and maps to get an idea of the type of soil in your area. Maps generated by scientific studies and surveying can point you in the right direction.
Whenever I recommend any metal detector to a customer, I examine the maps found in a U.S Geological Survey Professional Paper entitled, “Element Concentrations in Soils and Other Surficial Materials of the Conterminous United States.” In particular, I examine the map of iron-rich soil. Don’t be intimidated by the long title, the map is easy to read and understand.
The darker areas on the map indicate high levels of iron while the lighter/hollow areas represent little to no levels of iron. As you can see, areas in the Pacific Northwest such as Oregon, Washington and Northern California have high levels of iron-rich soil. If you’re planning to metal detect in these areas, you need a detector with manual and/or automatic ground balancing.
Doing your research up-front can save you tremendous amounts of time and heartache, but there’s no better research method than talking to fellow detectorists in your area.
Good luck and happy hunting.
U . S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 1270
Element Concentrations in Soils and Other Surficial Materials of the Conterminous United States
By HANSFORD T. SHACKLETTE and JOSEPHINE G. BOERNGEN