The stages and ages

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The stages and ages, as they are called-the subdivisions of all of the epochs and eras-read like a roll call in a district council somewhere in Armenia. Berriasian, Va langinian, Hauterivian, Barremian, Bedoulian, Gargasian, Aptian, Albian, Cenomanian, Turonian, Coniacian, Santonian, Campanian, and Maastrichtian, reading upward, are chambers of Cretaceous time. Actually, the Cretaceous has been cut even finer, with zakelijke energie about fifty clear time lines now, subdivisions of the subdivisions of its eighty million years. The Triassic consists of the Scythian, the Anisian, the Ladinian, the Camian, the N orian, and the Rhaetian, averaging seven million years. What survived the Rhaetian lived on into the Liassic. The Liassic, an epoch, comes just after the Triassic and is
the early part of the Jurassic. Kazanian, Couvinean, Kopaninian, Kimmeridgian, Tremadocian, Toumaisian, Tatarian, Tiffanian … When geologists choose to ignore these names, as they frequently do, they resort to terms that are undecipherably simple, and will note, typically, that an event which occurred in some flooded summer 34i.27 million years ago took place in the “early late-middle Mississippian.” To say “middle Mississippian” might do, but with millions of years in the middle Mississippian there is an evident compunction to be more precise. “Late” and “early” always refer to time. “Upper” and “lower” refer to rock. “Upper Devonian” and “lower Jurassic” are slices of time expressed in rock. In the middle Mississippian, there was an age zakelijke energie vergelijken called Meramecian, of about eight million years, and it was during the Meramecian that the Tonka-the older of the formations in the angular unconformity in Carlin Canyon, Nevada-was accumulating along an island coast. The wine-red sandstone and its pebbles may have been sand and pebbles of the beach. The island was of considerable size, apparently, and stood off North America in much the way that Taiwan now reposes near the coast of China.

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