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
Ring of Fire II Ring of Fire II Ring of Fire II is a 2008 anthology created by editor-author-historian Eric Flint. It is the second anthology in the 1632 series following after "Ring of Fire" (2004). The initial Ring of Fire book was a notable departure in that it heralded a new era in writing series fiction by being set in an authors' milieu shared with other writers, but especially and uncharacteristically by doing so without the control of the milieu creator, its author. Flint, in explanation, has self-styled himself as something of a gambler; he demonstrated that by deliberately asking the other writers