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 III stand out". Ring of Fire III Ring of Fire III is an anthology created by editor-author-historian Eric Flint, first published in hardcover by Baen Books in July 2011. It is the third anthology in the 1632 series following after "Ring of Fire II" (2008). The book includes twenty short stories, together with a preface by the editor. The Preface by Eric Flint explains the contents of this anthology and mentions future works. The reviewer for SFRevu said that "this collection contains high quality and stories that are important to the development of the 1632 universe" and that "fans of the