The great leader Comrade
"The work is also of no significance, if it is confined merely to discovery. Excavated relics can prove their true worth only when they are properly classified, analyzed and synthesized."
It is very important to classify excavated relics correctly and date them exactly in order to make the relics valuable. For this, various absolute dating techniques are widely applied to relics in archaeology. Luminescence dating, one of the absolute dating techniques in archaeological research, has been developed in past 60 years since the end of 1950s through several stages.
Luminescence dating technique is employed to estimate absolute ages of geological objects formed by some geological action of minerals and rocks etc. and archaeological sites and relics including heated materials, for example, potteries and burnt stones by using luminescence phenomenon of special minerals.
This technique is widely used for dating potteries, tiles, bricks, burnt stones and others and identifying authenticity of ancient relics.
It can be classified into thermoluminescence (TL) and optically stimulated luminescence (OSL) according to the method to obtain luminescence.
TL dating is a significant means to fill a gap between radiocarbon dating(~50ka) and K-Ar dating(~1 000ka to the age of the Earth) as it's measurable age range is from hundreds to millions of years.
Some research is under way to widen the measurable age range of OSL dating because of its range limited from hundreds of years to ~300ka.
The course of development in luminescence dating can be divided into three stages depending on its applicable objects.
In the first stage (1957-1979), TL dating was applied to mainly heated materials. It was found out in the late 1960s that TL dating was a very useful method for authenticity testing of ancient ceramics and therefore, it was applied to some ancient relics. Lots of TL dating results of archaeological materials and authenticity testing of ancient relics were published in the late 1970s. Representative examples of them were the authenticity testing of a double-headed vase and a bronze horse. Dating heated materials such as potteries, burnt quartz, burnt flints was conducted actively in the 1970s.
In the second stage (1979-1985), TL dating technique of sediments was developed continuously. TL dating on the sedimentary deposits of archaeological sites was performed by using TL signals of calcite and TL dating results of the Neolithic burnt stones were compared with radiocarbon dating results of related remains of them.
In the third stage (1985-1999), OSL dating technique was established and exact and rapid OSL readers completed. OSL dating on flints collected from several caves in the world was done between 1992 and 2003.
OSL dating was applied to lots of sediments over the world. It was discovered that it was possible to date old sediments aged ~300ka by using OSL through the OSL dating on an archaeological site in a certain country.
Now luminescence dating readers have TL equipment simultaneously with OSL one.
Work to use TL phenomenon of some minerals to date archaeological and geological objects has already been carried out since 1980s in the DPRK. Some researchers manufactured TL readers, found out the best measurable conditions, dated objects consisted of basalt, quartz and calcite. Through this course, the method of dating sediments of limestone caves was developed and then several ages of sediments in cave sites from the Palaeolithic to the Neolithic era including Tongamdong site of the early Palaeolithic era.
TL age of Layer 5 in the sediments of Tongamdong site dated back to ~740ka, which was published in "Journal of Archaeological science: Reports"(19, 405-410) with the title "Thermoluminescence dating of stalactitic calcite from the early Palaeolithic occupation at Tongamdong site" (https://doi.org/10.1016/j.jasrep.2018.03.022).
It was proved that volcanic lava contained human fossil bones was erupted ~300ka years ago, so the humans were assigned to the mid-Palaeolithic era.
There were also dating on Ryonggok cave site-1 (Layer 8-~110ka, Layer 10-~80ka) in Sangwon County, Pyongyang City and Chongphadae cave site (Layer 7-~60ka) in Sungho County, North Hwanghae Province.
In addition, TL dating results of Hyangmokri cave site (Layer 4-~30ka) and Juhyondong cave site (Layer 2-~10ka) showed that the area around Pyongyang has long history, where Korean ancestors lived long years ago. The results were published in "Journal of Archaeological science: Reports" with the titles "The age of the Palaeolithic sedimentary layer of Hyangmokri cave site in the Democratic People's Republic of Korea" (https://doi.org/10.1016/j.jasrep.2020.102681) and "Age determination of the Neolithic Juhyondong Cave site in the Democratic People's Republic of Korea" (https://doi.org/10.1016/j.jasrep.2019.02.014).
On top of them, a lot of attempts to apply TL dating for archaeological research were made during the last decade and some work has been under way to determine ages of sediments in newly excavated sites.
What is important in applying luminescence dating for archaeological research in the DPRK is to widen the measurable age range and find new applicable objects as many as possible.
Research will be further carried out into raising accuracy and widening applicable objects of luminescence dating, conducting heated materials like potteries, tiles, bricks, furnace sites etc. and testing authenticity of valuable ancient ceramics in future.
