The 366 daily episodes in 2014 were chronological snapshots of earth history, beginning with the Precambrian in January and on to the Cenozoic in December. You can find them all in the index in the right sidebar. In 2015, the daily episodes for each month were assembled into monthly packages, and a few new episodes were posted. Now, the blog/podcast is on an occasional schedule with diverse topics, and the Facebook Page showcases photos on Mineral Monday and Fossil Friday. Thanks for your interest!

Tuesday, July 1, 2014

July 1. The Pennsylvanian begins




Eastern Pennsylvanian showing coal areas (public domain, from an old text)



As we discussed at the start of the Mississippian Period last month, in the world of geology outside the United States, the Mississippian and Pennsylvanian together comprise the Carboniferous Period. In the U.S. the two are treated as full periods of geologic time, but the Pennsylvanian that begins today is the Late Carboniferous everywhere else. 

The late Carboniferous, or Pennsylvanian, is rich in coal-bearing rocks in many parts of the world, and that coal gives its name to the Carboniferous, meaning carbon-bearing. The Pennsylvanian in the U.S. is named for the state of Pennsylvania, where excellent exposures of coal of that age are found. The informal usage of the names Mississippian and Pennsylvanian received official recognition in the U.S. in 1906.
—Richard I. Gibson

No comments:

Post a Comment