Circum-Superior Belt event in Australia and 1,860 million year old magmatism of the Mashonaland event in Africa. The other questionable suggestion related to the Circum-Superior Belt is the existence of a suggested 1,900 million year old global superplume event. The long Labrador Trough, extending from Ungava Bay through Quebec and Labrador, includes two volcano-sedimentary series, the first ranging from 2,170 to 2,140 million years old and second ranging from 1,883 to 1,870 million years old. This magmatism is considered to have formed as a result of back-arc volcanism. The youngest magmatic series (1883-1870 Ma) contains 1,880 million-year-old carbonatites and lamprophyres. 1,883 to
Circum-Baikal Railway Trans-Siberian railway on either side of Baikal was linked, and began to be used to transport goods and passengers. The Circum-Baikal was called the "golden buckle on the steel belt of Russia". Initially, only one track was built; from 1911 to 1914 the construction of a second track was undertaken, which increased capacity of the Circum-Baikal to 48 pairs of trains a day. In this stage of the construction of bridges and other engineering structures reinforced concrete was introduced as a new material. As part of these works, considerable attention was paid to the construction of stations and station towns.