GROUND WHICH ONE PROSPECTS

The ground is an alive, unstable and complex medium.

It will have taken millenia to transform this rock which one names planet in a friable matter which is called ground.

The science of the grounds is named: Pedology (that is not invented). This very complex field asks for concepts of geology, of chemistry and of biology because the ground is alive, we go each day on billion micro-organisms resulting from the plants, but also from the dejections of animals.

The matter which will follow is not a thesis on the ground, but essential information for an effective prospection, very often the prospector neglects this element, which involves a loss of power of its apparatus. Certain manufacturers of detectors add a corrector of ground effects to reduce this disadvantage.

There are three ground effects and not two!

One is reminded that the ground effect disturbs the electromagnetic waves generated by a too strong mineral concentration contained in the ground (those behaving like metals or being tiny metal parts).

- the first are in general of natural origin. Thus your detector will have evil to pass the grounds of the center of France, Brittany (close to the coasts), Corsica, etc...

- However there are different ground effects due to the human activity. Like the precedents, if your aircraft is equipped with a corrector of ground effects, you will not even notice them. The problem is that you will not notice either that your apparatus does not detect with more than 10 or 15 cm because of this ground become very difficult to pass. Moreover very often the ground effects can vary quickly place with another, the adjustment recommended 5 minutes before does not correspond more 5 minutes afterwards. An adjustment of correction not adapted for a type of ground given will generate to him also a loss of the power.

- the third and last ground effect are that which one can meet on the ranges, just where the sea comes to lick sand. At this precise place a detector not studied for the range will sound over the entire length of the range! Making any detection impossible because the apparatus does not compensate for sodium chloride contained in the water which behaves like a soft metal
chemically (see the article on the ranges).

For this reason it is significant at the time of any purchase to ask well whether one can prospect with the object of your temptation where the waves are failed (for the case where one day you would decide to seek some lost ring).

In the contrary case and if your salesman is not sure answer, buy an adequate apparatus.

Various grounds and their characteristics

ARABLE LAND:

It is the surface layer of the gardens, parks, and other kitchen gardens of which the thickness varies according to places' between 10 and 40 cm maximum. The weight of the alive beings contained in this one represents approximately 700 G / Cubic meter. Of Lombrics, insects and especially of the billion bacteria and mushrooms microscopic use the composition of all the grounds, the role of all this small world is multiple: Some act on the decomposition of the vegetable scrap and the animal waste, by transforming the organic matter into assimilable mineral elements by the plants. Others fix atmospheric nitrogen of the air, thus fertilizing the ground, solubilize phosphates or potash to make it possible the plants to nourish itself. The arable land is subjected to innumerable chemical reactions due to the interactions between the various elements which composes it. The degradation of the organic matter led to obtaining mineral substances: nitrogenize, acid phosphoric, potash, lime, oligo-élements.

In short, the chemical properties of the grounds are directly related to their content of nutritive elements. The chemistry of the grounds takes account also of their reactions. A ground can be neutral, basic or acid or alkaline (limestone). Another element which determines the quality of the ground, it is its structure. The arable land consists of particles. The finer they are and the more they have
tendency to agglomerate (case of clay). Conversely, a more granulous structure (sand) gives a more ventilated ground.

THE GROUNDS LIMESTONES:

A ground is known as limestone when it contains between 10 and 40% of active Lime carbonate. One recognizes it by his rather clear color with marks blanchâtres. This ground is gorged quickly with water, but is cleansed very quickly because it is very permeable. A significant characteristic is that it is heated quickly what makes it possible the vegetation to be earlier (the best wines are produced on grounds limestones, our ancestors were not unaware of it). Active limestone obstructs the assimilation of iron by the plants, of or the frequent appearance of deficiencies; the foliage is faded while yellowing; the vegetation remains weak (what arrives when the content limestone is too significant). The wild vegetation which growth is called there calcicole (the plant with absolutely need for limestone to live) thus it is not rare to see pushing poppy, mustard, genévrier, cornflower... in the grounds limestones or those containing some ruins. In addition certain plants cannot push in the grounds limestones (they are called calcifuges).

Be thus vigilant with any abrupt change in the vegetation, especially if different surface is small and appears to delimit a quite precise zone. If you note such an anomaly, there are strong chances so that you discovered an archeological site or all at least an old place of habitat. Be thus very careful especially if you decided to use your detector, in the event of discovered of objects or of ancient currencies do not hesitate with us to make of it share, we will do what is necessary.

CLAY SOILS:

Clay is a tender sedimentary rock, soaked with water, clay becomes malleable what enables him to be used in pottery. Cooked once it hardens and is shown perfectly impermeable.

Clay is unattackable by the acids (known property of our ancestors). White when it is pure (KAOLIN), clay is generally reddish, colouring which had with iron. For information if one could separate all the particles contained in 30 G from clay, they would cover a total surface of 2 hectares! These particles, extremely fine measure approximately 0,002 m/m or a feeling of softness when one kneads it with the fingers.

Disadvantages of this ground: sticking, heavy, crack and river the summer, and hardens on the surface under the action of heat. On this generous ground for the culture, the use of a solid tool more than is recommended.

The spontaneous vegetation that one finds there is varied and abundant: dandelion, bindweed, wild rose, houx, ivy, clover.....etc. The clay soils are rather difficult to penetrate electromagnetically speaking. Their high percentage of iron and other oxides will not make it possible your detector to use all its power. One with estimated according to test the loss at at least 10 to 25% compared to a neutral ground (sand). Moreover when clay is not not combined with a little limestone, its pH is generally acid. What causes to corrode the beautiful patinas (for bronze and copper) and does not contribute to the conservation of the hidden objects. The chances to find objects in good condition are thus weak.

SANDY GROUNDS:

Friable and porous the sandy grounds meet in edge of sea and in the areas having formerly been covered (by the sea). The coarser sand is and the filter the ground is ventilated and. This ground gives an impression of lightness because it does not stick to the tools. And yet sand is constituent grounds heaviest (2 tons with the cubic meter).

The disadvantage of this ground in addition to the abrasive effect of with sand on the objects is that they are often acid. This fact it pushes a particular vegetation; Birch (forest of Fontainebleau) Maritime pine, some times but more rarely Houx (formerly called Fragon). In general these grounds are relatively poor, one seldom practised cultures there. Their only
advantages resident in the fact that very often these grounds is neutral and it is there that your detector will give best itself. Other positive point at the time of a large downpour the ground is wet up to 40 cm of depth what there still allows unequalled performances in any ground.

GROUNDS HUMIFERES:

It is a ground which contains more than 15% of humus. The humus consists of all organic waste resulting from the decomposition of the sheets, died animals, etc... it is a ground of black color and whose whole of its components are sustances organic complexes.
Generally acid (presence of the humic acid) these grounds thus do not preserve in good condition the objects metalic which they can contain. The example of the forest humus is most obvious: the concentration of humus is so strong, that it is found almost pure. The old meadows can be also humus-bearing grounds, for this reason in the absence of pines or fir trees (these two species being known for the acidity of the grounds which surround them) objects or currencies which could be discovered are corroded and almost deprived of patina. The silico-humus-bearing grounds (mixture of sand and humus) constitute the element of choice of the development of plants such as heathers, ferns, foam, lily of the valley. One will thus avoid the planted zones such species. As an indication the pH of a humus-bearing ground can déscendre below 5,5 what starts to be frankly acid. Only the gold or silver objects will not be attacked, but the chances to find such objects in these grounds are rare, these grounds being poor, one rather reserved them for hunting that for the cultures.

This article at summer carried out thanks to the review Super-guide N°75 my garden " of the plants for each ground " (found at Truffault). And also at a few years of experiment on the ground.