Circum-Superior Belt northwestern Superior craton margin intrude an older, 2,090 to 2,070 million-year-old dike swarm. The Ospwagan Group is younger than and the 1,864 million-year-old Winnipegosis komatiite belt lies to the southwest. Numerous tectonic settings have been suggested for triggering magmatism in the Fox River Belt, including a marginal basin rifting event. At the southern portion of the Circum-Superior Belt, a group of fragmental sediments composed of iron formation was formed during a period of magmatic activity in the Marquette Range Supergroup. Included in the Marquette Range Supergroup is the Hemlock Formation, a bimodal volcanic group that is estimated to have an
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.