The Precambrian in Alaska, US

Paleontology and geology

Marine conditions were widespread during the Precambrian of Alaska, although rocks of this age are rare or metamorphosed beyond recognition from their original forms. There is some evidence of rocks that were formed on the margin of a shallow continental shelf and in deep water, as well as rocks formed in related island arcs. Most fossil-bearing rocks date from the Late Proterozoic (650 to 550 million years ago) and yield stromatolites and other cyanobacteria.