- Welcome to the U. S. and Canada Obsidian and FGV (Fine-Grained Volcanic Toolstone) Source Mapping Project home page. For many years, we’ve been chasing down obsidian and FGV sources in the western United States and have promised that someday - when enough source information was finally available - we would begin creating maps that illustrate the geographic patterning of these archaeologically-significant prehistoric sources of natural glass and volcanic toolstone. That day has finally come and we are currently in the process of assembling and producing source maps for the western United States and Canada. Along with a few states (and provinces) for which we still lack good GIS coverages or adequate source data, we’re currently working on regional maps that illustrate the spatial ranges of several geographically-extensive sources.
- Mesoproterozoic (Wikipedia)
The Mesoproterozoic Era is a geologic era that occurred from 1,600 to 1,000 million years ago. The Mesoproterozoic was the first era of Earth’s history for which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic), but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, although their arrangement on the Earth’s surface was different.