US w alternatives
Dr. Ron Blakey's website provides a very good overview, complete with maps, of the geologic history of the western US.
Geologists continue to debate the merits of alternative interpretations of the geological history, from 270 to 150 Ma, of the western US. In one interpretation, most elements of the western US are assumed to have been derived tectonically from North America. In the second tectonic interpretation ("or"), in which some exotic elements are considered to have originated far from North America (accreted terranes).
Roll-over the 'dated' links for preview images of maps of the time periods, or visit the website for links to major periods. Click here for all geological maps in sequence.
roll-over links for maps: continental sequences: 1.7 Ga, 1.1 Ga, 650 Ma, 510 Ma, 470 Ma, 430 Ma, 370 Ma, 340 Ma, 310 Ma, 280-270 Ma, 250 Ma, 240 Ma, 215 Ma, 200 Ma, 170 Ma, 150 Ma, 145 Ma, 130 Ma, 90 Ma, 75 Ma, 65 Ma, 50 Ma, 35 Ma, 20 Ma, 10 Ma ; offshore, to west of continent: contiguous interpretation: 470 Ma w, 430 Ma w, 370 Ma w, 340 Ma w, 310 Ma w, 280-270 Ma w, 250 Ma w, 240 Ma w, 215 Ma w, 200 Ma w, 170 Ma w, exotic interpretation: or 270 Ma w, or 250 Ma w, or 170 Ma, or 158 Ma, or 155 Ma.
Geologists continue to debate the merits of alternative interpretations of the geological history, from 270 to 150 Ma, of the western US. In one interpretation, most elements of the western US are assumed to have been derived tectonically from North America. In the second tectonic interpretation ("or"), in which some exotic elements are considered to have originated far from North America (accreted terranes).
Roll-over the 'dated' links for preview images of maps of the time periods, or visit the website for links to major periods. Click here for all geological maps in sequence.
roll-over links for maps: continental sequences: 1.7 Ga, 1.1 Ga, 650 Ma, 510 Ma, 470 Ma, 430 Ma, 370 Ma, 340 Ma, 310 Ma, 280-270 Ma, 250 Ma, 240 Ma, 215 Ma, 200 Ma, 170 Ma, 150 Ma, 145 Ma, 130 Ma, 90 Ma, 75 Ma, 65 Ma, 50 Ma, 35 Ma, 20 Ma, 10 Ma ; offshore, to west of continent: contiguous interpretation: 470 Ma w, 430 Ma w, 370 Ma w, 340 Ma w, 310 Ma w, 280-270 Ma w, 250 Ma w, 240 Ma w, 215 Ma w, 200 Ma w, 170 Ma w, exotic interpretation: or 270 Ma w, or 250 Ma w, or 170 Ma, or 158 Ma, or 155 Ma.
Labels: accreted terranes, contiguous or exotic alternatives, Regional Geological History, western United States