An intimate visit to the Cretaceous-Tertiary boundary

May 21st, 2010

Cretaceous-Tertiary boundary at Mussel Creek, Lowndes County, Alabama (N 31.97176°, W 086.70414°). Megan's hand marks the level with the Cretaceous below and the Tertiary above.

A closer view of the same boundary. My finger is thrilled to be in such a place.

GREENVILLE, ALABAMA — It is one of the most famous geological horizons.  It marks the end of the Mesozoic Era and the beginning of the Cenozoic.  The “K/T boundary” is dated at 65.5 million years ago (±0.3 my) and is found around the world.  It is the primary datum for our work on this expedition, and we were led right to it by our friend Jon Bryan.  We want to just pause a moment and enjoy the historical and stratigraphic significance of these sediments.  (And yes, I know I should be calling this the more modern “Cretaceous-Paleogene Boundary” as Megan insists, but I grew up with “K/T” since my Berkeley graduate school days and it is hard to give up!)

More later from our hot and muggy day in southern Alabama!

7 Responses to “An intimate visit to the Cretaceous-Tertiary boundary”

  1. Ron Schotton 21 May 2010 at 5:06 pm

    K/T is just fine with me, but K-P(i)g is OK, too, mainly because of it’s “rock” related double entendre.

  2. Mark Wilsonon 21 May 2010 at 5:43 pm

    I had to look that one up, Ron, and now I get it!

  3. Lynon 21 May 2010 at 10:00 pm

    Those ferns are also thrilled to be in that place! And looks like a little moss there on the closeup! Glad you are having fun and getting some good stuff.

  4. Meagenon 22 May 2010 at 10:43 am

    Did you bring back a sample that I can zap in my labs? It would be neat to see if we could detect the Ir ourselves (I’ve never done that before!)

  5. […] some unusual complexity.   At the southern end of the section it is simple enough, as shown in a previous blog post.  Just a few meters north, though, the boundary section looks like this: Cretaceous-Tertiary […]

  6. Mark Wilsonon 22 May 2010 at 4:21 pm

    That would be fun, Meagen! The problem, though, is that at this locality we were so close to the impact that tsunamis and other effects (see above) have ensured there is no preservation of a discrete iridium-rich clay layer. We may find some material later that we can submit to your magic lab.

    Hope the field trip is going well!

  7. […] effects. I should add that I visited the Cretaceous-Paleogene boundary this past summer in Alabama, Mississippi, Israel and The Netherlands, so I’m passionate about this story! We will briefly […]

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