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
Ring of Fire (anthology) "topnotch choice for alternate history fans and essential for libraries owning 1632 and 1633" and that these "15 stories contribute directly to the main plot lines of the series and illustrate the complex and multifaceted nature of historical fiction." Ring of Fire was listed on the Locus (magazine) Hardcovers Bestsellers List for two months in a row during 2004, topping at number 2. Ring of Fire (anthology) Ring of Fire is the third published book by editor-author-historian Eric Flint of the 1632 series, an alternate history series begun in the novel "1632" (February 2000). The "Ring of Fire" is both