Electrical resistance method for detection of effects
The way how traditional core drilling operation for archaeology is a method of archaeological work despite the threat of trouble and difficulties and problems and obstacles while searching for buried effects. Excavations have prolonged and boring to many years without that up “to their goal, it increases the difficulty of the wider area of the archaeological site and its many hills and ravines leading walakam, that has led some archaeologists to use modern science and technology to save effort, time and money, especially if those responsible need to land for agriculture and reconstruction projects or paving roads or any other business.
And AIDS in this way or geophysical forecast methods that rely mostly on counters resistance such as electrical resistance that rely on measuring soil resistance to electric current, if, for example, resistance to electricity, be evidence of the existence of walls or buildings. Because the stones are resistant to electricity by degrees vary depending on the hardness of other prescriptions, as well as the soil if the dissolved salts they become good conductor of electricity (1).
1 history of the emergence of an electrical resistance:
It was the first use of electric resistance method in 1964, and was the first geophysical methods used in detection of buried in the ground effects. And geophysical methods (Geophysical Methods) that can assist archeology using theories of physics to detect geological structures of the Earth’s crust and learn then what in this land of archaeological treasures, whether antique or not (2).
2 1 area of use and applications:
Research on the methods adopted generally to scientific expertise in this area where most archaeological hills know the result recorded in the historical books or compared to the surrounding land around the Highlands, who take the archaeological (broken pottery, glass …) covering most of the hills. There are many sites that are found as a result of human actions, such as agriculture or dig trenches and other.
The Geophysics is a vast science covering the study of physical properties of Earth, which reveals the subsoil, the interpretation of geophysical measurements in many areas, including metal detectors, and raw materials, and groundwater, oil, underground structures, caves, as well as measure the intensity of earthquakes and other. It may not be surprising if we find this science used every day in new areas. We find geoscientist is the detection of effects. The geophysical methods, methods used to detect the effects of magnetic and electrical resistance method and electromagnetic radiation. Either methods most used in the investigation and have been used in the detection of many effects in the world:
1 how magnetism Magnetic Method
2 way Electrical Rcaistiviting electrical resistance Method
The advantage of using these methods is fast and inexpensive, so they appear in the spacious sites too. Also, these methods are not spoken any damage to archeological and use you can set the quality and extension of the archaeological and building his assemblings.
Thus, there are many archaeological sites lacking Geophysical to develop a clear picture of the focus and monuments. There are also many archaeological sites are susceptible to damage and for the reasons mentioned above, in this case, geophysical surveying, identification and preservation of monuments under the Earth’s surface without drilling to be ready full exploration and maintenance (3).
3 1 operative technique:
That the basis for the use of geophysical methods is a difference in physical characteristics between the archaeological body and surrounding materials. This difference is why the events of abnormalities or deviations (Anomaly) in the field where readings will help set the monuments. The value of the gay positive (Positive Anomaly), in the event that the archaeological material of high physical properties, more than the surrounding material. And on the contrary any archaeological material in the case of physical properties of buried material in Queers are negative (Neyatine Anomaly).
As well as the electrical resistance, used in the investigation of groundwater, minerals and know the layers beneath the Earth’s surface and is the first geophysical method applied in the detection of effects.
This method relies on the existence of differences in electrical resistance (Resistivity Contrast), between the archaeological object “body designed to look”, and the surrounding material, it is known that rocks vary in susceptibility of electrical conductivity, this difference depends on several reasons, including gaps, as well as the quality of constituent minerals of these rocks. Etc. Generally be igneous rocks (Igneous), more reluctant to electricity from sedimentary rocks (Sedimentary Rocks), to fit the gaps, and soils (Soil), clay (Clay), the susceptibility to high electrical.
For the purpose of field measurements to demonstrate on Earth four electrodes (Electrods), two of them used to pass electrical current and designated electrical poles (Current Electrods), the other the poles used to measure potential difference and labeled with voltage electrodes (Potential Electrods).
During the screening process on the Poles are installed in two ways:
Method 1: called Wii seen (Wenner Configuration), which distributed the electrodes as shown in figure (a) and take the voltage electrodes electrodes are equal distances between the four poles. And choose the distance between electrodes based on depth effects to be detected and the form of abnormality as shown in figure (a).
The second way: they called a bipolar (Dipole Dipole), and in this way prove electrodes effort on both ends of the electrodes, and the abnormality as shown in figure (b). For each of these methods has its benefits and disadvantages.
After you install the electrodes are measuring the voltage difference when passing electrical current through a special measuring device called a measurement of electrical resistance (Resistiviting-meter), where electrical resistance is then calculated by the following equation:
Electrical resistance (OHM) current (AMPS) voltage (volts) x fixed.
“The value of the constant depends on the distance between the electrodes”
In the case of homogeneity between ground layers, the movement of electricity be regular. In the case of a reluctant electric body different from the surrounding layers change occurs in a path, and then composed oddities. By studying this anomaly by co-Chairman specialists can identify the characteristics of pathogenic organisms that change and their location.
4 1 geophysical results view:
The problem facing Co-Chairman in detecting effects are frequent field readings, so only chose good ways to represent these results and a simplified form for the purpose of interpreting geophysical and then translate these interpretations to the archaeological area.
Of the methods used in geophysical results are:
1 offer to form paths (Profiles), this is the simplest way to represent the geophysical results where read coordinates one representing the site reading “sigmoid” events, and the other represents the value of “y” events
(C). Sudden change in values will represent the geophysical anomaly (Geophysical Anomaly), and used this method in the display if the initial examination of the site in order to get a quick idea of the geophysical values on site.
2 a contour map: in this case draw curved lines connecting points with equal values with each and the final map contains a number of contour lines and each line its own value. And consideration of the maps can specify the sites where construction is concentrated.
3 symbols (Symbols): this way of representing values with different codes, and usually high values are represented by dark or large icons, low values also left without the sometimes, or use a light codes. And here we must recall that some archaeological objects have adverse and the property taken into account low values as well as the possible use of colors to select sites that buildings are concentrated, so that different colors for geophysical values.
6 1 the strengths in the way:
1. low vulnerability to external phenomena that can be applied within cities as can be used to investigate the effects of different magnetic property but with different electrical properties in locations where it is difficult to apply magnetic method.
2. the geophysical survey does not need a cadre, Geophysicist geophysical devices could be used by staff trained in its use.
3. not spoken any damage to archeological and use you can set the quality and extension of the archaeological and building his assemblings.
4. fast application and low cost.
5 1 the weaknesses in the way:
1. large field readings so necessitated chose good ways to represent these results.
2. the installation of the Poles in the ground makes the slow way.
3. the application of the method of electrical resistance you need four people to accelerate the field readings.
4. difficult to use the way in rocky areas (special mountain) and to the difficulty of installing electrodes.
5. as it is impossible to apply them in locations where groundwater close to the surface for the presence of water leads to a difference in electrical resistance values.
6. it is difficult to apply this method in the arid areas
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