Missourian

Show Your Period Boundaries

14 posts in this topic

Do you have photos showing the boundary between strata of two different geologic periods or epochs? If so, put 'em here....

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I'll start things off....

Mississippian-Pennsylvanian boundary

Burlington-Keokuk Limestone - Cherokee Group

Osceola, Missouri

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Here, Pennsylvanian shale and sandstone fills a sinkhole formed in the deeply weathered Mississippian limestone.

Edited by Missourian

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I just posted this exact thing on your other thread, but since it holds more relevance here, i'll post it again:

This is one of the sites where i collect at, which yields complete Glossopteris leaves. As you can see by the pic, it is a great place to see the Permian-Triassic boundary, notorious for being the most devastating extinction event in the planets history (95% of life wiped out in a geological blink). It is located at Austinmer, a coastal suburb between Sydney and Wollongong.

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i'll post it again:

Thanks much. I hope there are many more to follow....

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Precambrian-Cambrian boundary

Vishnu Schist - Tapeats Sandstone

Bright Angel Trail, Grand Canyon, Arizona

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It's just up the trail now:

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I couldn't tell where the trail crossed the boundary.

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Hello!

Here a small movie from the KT boundary in Denmark where I have hunted during 3 years. Now, When I come back from Sweden and my way back to France, I like to make a small stop there...

It was this year, Beginning of April.

Enjoy

D

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nice video, dromiopsis... nice fossils. My pix of the KT boundary in Wyoming are lost in badly organized photos.

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I don't actually have a picture but there is a well defined layer exposed at Ridgemount quarry in Ontario, Canada where the Upper Silurian meets the Lower Devonian. Perhaps Pleecan might have a picture of this.

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Can I ask that people state whether there is an unconformity at their boundary, if they know it? For instance, Missourian, I believe there is one between the Vishnu and Tapeats?

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K-T boundry at Moscow Landing, Tombigbee River, Sumter County, Alabama. Mid-Maastrichtian Prarie Bluff Fomation (Chalk) and Mid-Danian Clayton Formation.

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Can I ask that people state whether there is an unconformity at their boundary, if they know it? For instance, Missourian, I believe there is one between the Vishnu and Tapeats?

Yes, both are definitely unconformities. :)

The Precambrian termination is the granddaddy of all unconformities. It is often referred to as the "Great Unconformity". Technically, it is a nonconformity here where it overlies the Vishnu Schist.

The pre-Pennsylvanian gap shown above is a major disconformity across the Midcontinent. In many spots, it is underlain by Devonian or Ordovician rocks.

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A definite unconformity. Maastrichtian Peedee Formation and Bartonian Castle Hayne Formation contact at the Martin-Marietta Rocky Point Quarry, Pender County, North Carolina circa 2002.

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Another one. Piacenzian Yorktown Formation, Rushmere member where all of the weeds are growing sitting on top of Campanian Black Creek Group sediments on the Roanoke River, Halifax County, North Carolina.

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Edited by MikeR

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Interesting... I'll have to think about where the bounds/contacts are in my area and get pix next time I'm out... weather has not been cooperating lately tho'. During a college field trip we were shown a spot in a roadcut near the college where a scientist took core samples to find where the magnetic field flipped.. that sort of thing might be interesting to post as well?

Edited by Wrangellian

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