east by the Late Carboniferous through Jurassic Verkhoyansk foldbelt, on the northwest by the Paleozoic Taymr foldbelt, and on the southeast, south and southwest by the Middle Silurian to Middle Devonian Baykalian foldbelt. A regional geologic reconnaissance study begun in 1932 and followed by surface and subsurface mapping revealed the Markova-Angara Arch (anticline). This led to the discovery of the Markovo Oil Field in 1962 with the Markovo—1 well, which produced from the Early Cambrian Osa Horizon bar-sandstone at a depth of . The Sredne-Botuobin Gas Field was discovered in 1970, producing from the Osa and the Proterozoic Parfenovo Horizon. The Yaraktin Oil Field was discovered in 1971, producing from the Vendian Yaraktin Horizon at depths of up to , which lies below Permian to Lower Jurassic basalt traps. Climate The climate of Siberia varies dramatically, but it typically has short summers and long, brutally cold winters. On the north coast, north of the Arctic Circle, there is a very short (about one month long) summer. Almost all the population lives in the south, along the route of the Trans-Siberian Railway. The climate in this southernmost part is humid continental climate (Köppen Dfb) with cold winters but fairly warm summers lasting at least four months. The annual average temperature is about . January averages about and July about , while daytime temperatures in summer typically exceed . With a reliable growing season, an abundance of sunshine and exceedingly fertile chernozem soils, southern Siberia is good enough for profitable agriculture, as was demonstrated in the early 20th century. By far the most commonly occurring climate in Siberia is continental subarctic (Koppen Dfc or Dwc), with the annual average temperature about and an average for January of and an average for July of , although this varies considerably, with a July average about in the taiga–tundra ecotone. The business-oriented website and blog Business Insider lists Verkhoyansk and Oymyakon, in Siberia's Sakha Republic, as being in competition for the title of the Northern Hemisphere's Pole of Cold. Oymyakon is a village which recorded a temperature of on 6 February 1933. Verkhoyansk, a town further north and further inland, recorded a temperature of for three consecutive nights: 5, 6 and 7 February 1933. Each town is alternately considered the Northern Hemisphere's Pole of Cold – the coldest inhabited point in the Northern hemisphere. Each town also frequently reaches in the summer, giving them, and