Oscar Montelius
Photo of a painting by Emerik Stenberg (1873-1927) which was published in the Swedish periodical Ord & Bild in 1913

Oscar Montelius (9 September 1843 Stockholm – 4 November 1921) was a Swedish archaeologist who refined the concept of seriation, a relative chronological dating method. Seriation is the procedure of working out a chronology by arranging material remains of a cultural tradition in the order that produces the most consistent patterning of their cultural traits.

His impetus was at first to provide relative dates for artefacts in museum collections that often lacked rigorous records, by making comparisons with other artifacts within a comparable geographical area. Montelius’ method created a timeline specific to the location, based on material remains. Later, when combined with written historical references, objects could be provided absolute dates.

He took the three-age system (Stone age, Bronze age, Iron age), originally devised by Christian Jürgensen Thomsen to organize Danish museum collections of archaeological materials, and sub-divided it further. He divided the Neolithic in Scandinavia into four numbered periods, I-IV, and the Nordic Bronze Age into six I-VI. He was the first to establish that the numerous Swedish petroglyphs were from the Nordic Bronze Age, by comparing axes portrayed in the petroglyphs with archaeological finds. Further he supported Thomsen’s typology of gold bracteates from the migration period.

Source Wikipedia.