Summary: The low sea levels of the Ordovician glacial period rebounded in the Silurian as the ice melted. Although much of Gondwana was still over the south pole, it appears that conditions were not right for glaciers, and the ice caps, if any, were much smaller during most of the Silurian than they were during the Ordovician glacial time. Map by Ron Blakey, via Wikipedia, used under CC-A-SA license. Still, sea level wasn’t quite as high as during much of the Ordovician, at least in parts of North America. We’ll discuss some of the variations later in the month. The Silurian map above shows Baltica, the Precambrian core of Europe, getting pretty close to North America, and the long narrow microcontinent, Avalonia, is getting caught between them. Siberia is to the northeast, and Gondwana is on the margins of the globe in the map above. Plenty of fodder for mountain building. We’ll talk about that, too, later in April as we get further into the Silurian Period. —Richard I. Gibson Map by Ron Blakey, via Wikipedia, used under CC-A-SA license.
