(Specifically, dark blue is late Paleozoic, lighter blue is Permian, and the greens signify Triassic, Jurassic and Cretaceous—see the time scale.) A great winding gash in the western part of the plateau is where the Grand Canyon exposes deeper rocks from the Precambrian.
Scientists are far from a settled theory of the Grand Canyon.
And just on the border of the embayment, a rare body of lamproite (the largest of the red spots) is the only diamond-producing locality in the United States, open for public digging as Crater of Diamonds State Park. Between the red swath signifying the Sierra Nevada granites and the western greenish-yellow band of folded and faulted Coast Ranges lies the great sedimentary trough of the Central Valley.
California offers a lifetime's worth of geologic sights and localities; the Sierra Nevada and San Andreas fault are the barest beginning. Elsewhere this simplicity is broken: in the north, the blue-and-red Klamath Mountains are torn from the Sierra and moved westward while the dotted pink is where young, widespread lavas of the Cascade Range bury all older rocks.
Large islands off the southern coast rise from sunken crustal fragments, part of the same vigorous tectonic setting.Like the Appalachians, these rocks produce coal and natural gas as well as various metals.The southwestern corner of the state yields petroleum from its early Cenozoic strata. Our ideas of geology have come a long way since then, but the rocks are still the same.The Geological Survey of Alabama has much more information on the state's rocks, mineral resources, and geologic hazards.Alaska is a colossal state that contains some of the world's most notable geologic features. The long Aleutian Island chain sweeping to the west (cut off in this miniature version) is a volcanic arc that is fed magma from the subduction of the Pacific plate beneath the North American plate.The edge of the Colorado Plateau, marked by the ribbon of darkest blue running from northwest to southeast, is the Mogollon Rim.The Basin and Range is a wide zone where plate-tectonic motions have stretched apart the crust as much as 50 percent in the last 15 million years or so.The crack has remained seismically active ever since.Just north of the state line along the Mississippi River is where the great New Madrid earthquakes of 1811–12 occurred.At the same time, magma burst up from below in widespread eruptions, leaving lavas marked in red and orange.The yellow areas are continental sedimentary rocks of the same age.