Russia: a neutrino telescope installed from lake ice, letters scratched on birch bark and mammoth radiocarbon dates from an Arctic island

UNESCO places Lake Baikal in south-east Siberia. In its southern basin, 3.6 km offshore where the lake is about 1,365 m deep, the Baikal-GVD collaboration is building a neutrino telescope on the scale of a cubic kilometre. Its optical modules, light sensors in pressure-resistant glass spheres, hang on vertical strings, 36 to a string and 15 m apart at depths between 750 and 1,275 m; eight strings make up a cluster. The lake is part of the instrument. Dmitry Zaborov, writing for the collaboration, notes that the ice, up to about 1 m thick from February to mid-April, serves as a solid platform for deploying and servicing the detector, and gives the light absorption length in the deep water as reaching 22 m. The first cluster was installed in 2016, and the November 2024 preprint reports 13 completed clusters occupying about 0.6 km³ of water.[2][1]

According to its city portal, Veliky Novgorod lies in the north-west of Russia, near where the Volkhov leaves Lake Ilmen. UNESCO describes the town’s archaeological layers of the 10th–17th centuries as covering about 347 ha, 7–8 m deep, waterlogged and anaerobic, which preserves organic materials. The first birch-bark letters were found there in 1951. In an overview published on gramoty.ru, A. A. Zaliznyak counts 1,209 such letters by the end of 2017, 1,102 of them from Novgorod, with finds in eleven other Old Russian towns. All but two were scratched with a metal or bone stylus; only nos. 13 and 496 are in ink. Most are 15–40 cm long and 2–8 cm wide, and only about a quarter survive whole, most often torn by recipients who did not want others to read them. The database lists letter no. 292, dated to about 1240–1260 (possibly somewhat earlier), as a charm, or incantation, in the Karelian language.[6][5][3][4]

Wrangel Island and Herald Island, with the surrounding waters, form the Natural System of Wrangel Island Reserve, which UNESCO places well above the Arctic Circle; Wrangel itself covers 7,608 km². UNESCO says it was not glaciated during the Quaternary Ice Age, and lists 417 species and subspecies of vascular plants, 23 of them endemic. A 2008 paper in Quaternary Research by Vartanyan and colleagues presents 124 radiocarbon dates on mammoth bone from the island, 106 of which fall between 3,700 and 9,000 years ago. The authors take these dates to bracket the period of mammoth isolation on the island and their extinction, which they attribute to natural causes. They also found that the island’s Holocene mammoths were comparable in size to mainland ones and cannot be classed as dwarfs.[7][8]