Circum-Superior Belt age of . Another volcanic series in the Marquette Range Supergroup, known as the Gunflint Formation, has an age of . Further geologic units that are related to the Gunflint Formation include the Badwater volcanics and the Kiernan sills. A number of origins have suggested for the Marquette Range Supergroup magmatism. This includes subsidence being driven ahead related to thrusting of the Penokean orogeny or a possible back-arc basin, and lateral flow through the Pickle Crow dikes transported magma from the Fox River Belt area through the Superior craton for placement in the Marquette Range Supergroup. This suggested long-range origin
Circum-Baikal Railway in operation: Kultuk, Maritui, Ulanovo, and Baikal, with one section of double track at 137 km. The Circum-Baikal contains thirty-eight tunnels with a total length of 9063 m (the longest of them, a tunnel through cape Polovinnyj, is 777.5 m long). There are also 15 stone galleries with a total length of 295 m and 3 ferro-concrete galleries with apertures, 248 bridges and viaducts, and 268 retaining walls. The Circum-Baikal has no equal in Russia as to the richness of engineering constructions. The tunnels and stone galleries of the Circum-Baikal are unique in that they were constructed atypically and have