Archaeological methods and techniques

Environmental and engineering geophysical methods play an important role in archaeology. Through high-precision magnetic survey on the ground, the magnetic difference between the distribution area of ancient sites and backfill soil is detected, and the position, boundary shape and occurrence characteristics of ferromagnetic objects in the sites are understood. Through resistivity method, induced polarization method, natural electric field method, geological radar and other means to understand the electrical differences between different rock and soil layers and various metal objects and media; Using seismic reflection wave and seismic surface wave to detect the elastic difference between the ancient tomb and the surrounding medium, and to explore the structural boundary and buried depth of the mausoleum underground palace. By using radioactive measurement technology, the distribution of underground structures in some mausoleum areas or ancient architectural sites is understood by measuring the change of radon concentration in natural gas. Using geophysical methods in archaeological work can realize nondestructive detection of ancient culture and improve the accuracy of archaeological excavation. For example, the Institute of Geophysics, Chinese Academy of Sciences used seismic surface wave, high-precision magnetic survey, geoelectric field lithologic detection, geochemical mercury measurement and other means to detect the Chu tomb in Guling in the Three Gorges reservoir area, accurately determined the location and distribution of the Chu tomb in Guling, confirmed the existence of the presumed tomb, and solved important problems for the rescue and protection of cultural relics in the Three Gorges reservoir area.

Archaeological research by geophysical methods mainly includes the following aspects.

(1) Archaeological exploration

Archaeological exploration is mainly to explore human historical sites on the ground, underground and underwater, such as ruins, tombs and shipwrecks. And gradually improve the application effect and expand the application scope in practice. The existing archaeological geophysical methods include almost all exploration geophysical methods, but each has its own characteristics. According to the different environmental conditions of application, it can be roughly divided into two categories.

A. Terrestrial archaeology and geophysical exploration

Aerial geophysical prospecting and remote sensing: including aerospace, aerial remote sensing and aerial geophysical prospecting, such as multispectral scanning, microwave remote sensing, thermal infrared measurement, airborne magnetic measurement and airborne electromagnetic measurement;

Electrical (magnetic) methods: mainly include resistivity method, ground penetrating radar method, natural electric field method, induced polarization method, very low frequency method and so on.

Magnetic method: mainly high-precision magnetic measurement, including soil magnetic susceptibility measurement;

Seismic methods: mainly include seismic surface wave method, seismic reflection wave method, seismic refraction wave method and acoustic wave detection method;

Geochemical measurement: mainly mercury measurement;

Gravity measurement: mainly microgravity measurement;

Nuclear geophysical methods.

B. Geophysical exploration on water

Magnetic method: when there is magnetic difference between underwater cultural relics and their surrounding media, magnetic method is an effective method.

Seismic and acoustic wave methods: to explore the depth of seawater, seabed sediments and large-scale cultural relics buried on the seabed, such as ancient buildings on the seabed.

(2) Dating of ancient relics

There are two geophysical methods for dating ancient relics.

A. Archaeological geomagnetic methods

This is an ancient method of dating cultural relics. The first is to determine the age of the cultural relics. At present, it has formed a branch discipline called magnetic stratigraphy.

B. Isotope method

(3) Protection and identification of cultural relics

The main methods used are ultrasonic method, resistivity method, magnetic method and nuclear geophysical method.