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Bjørn Sørheim
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 Posted: Tue Oct 07, 2008 4:56 pm Post subject: Is this a fossil? |
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The page explains it all.
Is it a fossil, or are we fooled by something else. If so, what??
http://home.online.no/~bsoerhei/geo/fossil/horneldevon/What_is_this.html
Bjørn Sørheim |
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J. Taylor
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| Posted: Wed Oct 08, 2008 12:08 am Post subject: Re: Is this a fossil? |
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On Tue, 7 Oct 2008 13:56:52 +0200, "Bjørn Sørheim"
<bsoerhei@nixspam.online.no> wrote:
[quote]The page explains it all.
Is it a fossil, or are we fooled by something else. If so, what??
http://home.online.no/~bsoerhei/geo/fossil/horneldevon/What_is_this.html
Bjørn Sørheim
[/quote]
Looks like chert
http://en.wikipedia.org/wiki/Chert
JT |
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Edward Hennessey
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| Posted: Wed Oct 08, 2008 2:42 pm Post subject: Re: Is this a fossil? |
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"Bjørn Sørheim" <bsoerhei@nixspam.online.no> wrote in message
news:48eb4e85$1@news.broadpark.no...
[quote]The page explains it all.
Is it a fossil, or are we fooled by something else. If so, what??
http://home.online.no/~bsoerhei/geo/fossil/horneldevon/What_is_this.html
Bjørn Sørheim
[/quote]
BS:
It might help if you share your indication of just what parts of the images
might be fossil. I>m assuming
you are talking about the element shaped like the fore-part of a round-nosed
shovel which bears some fishy
resemblance. Speaking from fugitive memory of my viewing this morning, my
initial response was that it was
just a layer of mineralization with a chance correspondence to a Placoderm
outline.
Reasons? It appeared to be mineral infilling as I see no suggestion of
differentiated structure either across the shape
or in its thickness. Were it fossil, I would expect there to be cracks
corresponding to stresses exerted along structural
lines. Also, there appears to be no sign of ornament or patterned breakage
along the edge of the piece which is
why I>m going with a mineral infiltration. If you can recall a tapering of
the thickness toward the edges that would be another
clue in the equation. There was a scrap or two on the slab that were more
likely candidates for organic origin though I
couldn>t say what without closer inspection.
Nice eye though. And fine scenery. There are some fine Eurypterids from
Norway that I>ve seen. If you get one,
let me know.
You can re-orient me if I targeted the wrong thing and you can also try the
query on sci.bio.paleontology where other
views may come.
Regards,
Edward Hennessey |
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Bjørn Sørheim
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| Posted: Thu Oct 09, 2008 1:41 am Post subject: Re: Is this a fossil? |
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"Edward Hennessey" <haloOUTzzyzxhalo@yahooOUT.com> skrev i melding
news:6Z-dnQOJt_g2HXHVnZ2dnUVZ_uGdnZ2d@earthlink.com...
[quote]
"Bjørn Sørheim" <bsoerhei@nixspam.online.no> wrote in message
news:48eb4e85$1@news.broadpark.no...
The page explains it all.
Is it a fossil, or are we fooled by something else. If so, what??
http://home.online.no/~bsoerhei/geo/fossil/horneldevon/What_is_this.html
Bjørn Sørheim
BS:
It might help if you share your indication of just what parts of the
images might be fossil. I>m assuming
you are talking about the element shaped like the fore-part of a
round-nosed shovel which bears some fishy
resemblance. Speaking from fugitive memory of my viewing this morning, my
initial response was that it was
just a layer of mineralization with a chance correspondence to a
Placoderm outline.
[/quote]
Yes, it>s what you see in the 3-4 first images that makes me ask the
question, mainly.
Also the light grey patches you see in the other images with a very fine
grained uniform
colour and texture, not like the more coarse grained sand stone itself.
If a Placoderm fossil should be found here it would be a first for such
finds of these exterminated
ancient fossil fishes.This group seems to be from lower devonian, and as
this area is interpreted to be
lower upper Middle devonian, they would most probably not be here.
Another possibility could actually be fossils from the first animals on land
(Ichtyostega etc.), as
they are roughly from this time period.
The few fish types (Osteolepid and Porolepiformes (plus some indetermined
fishes) - Sarcopterygians formerly
Crossopterygians) found here are from the types that these first land
vertebrates subsequently decended from.
[quote]
Reasons? It appeared to be mineral infilling as I see no suggestion of
differentiated structure either across the shape
or in its thickness. Were it fossil, I would expect there to be cracks
corresponding to stresses exerted along structural
lines. Also, there appears to be no sign of ornament or patterned breakage
along the edge of the piece which is
why I>m going with a mineral infiltration. If you can recall a tapering of
the thickness toward the edges that would be another
clue in the equation.
[/quote]
I got very little time to do a close examination when I was there, and I
didn>t have
a magnifier, but from thee initial look, they looked quite (uniformly)
thin. This area is
normally closed off to the public.
There was a scrap or two on the slab that were more
[quote]likely candidates for organic origin though I
couldn>t say what without closer inspection.
Nice eye though. And fine scenery. There are some fine Eurypterids from
Norway that I>ve seen. If you get one,
let me know.
[/quote]
These are found at Ringerike, eastern Norway, but not here, so far. But
there has been finds
of animal tracks here that is suggested to be from Eurypterids.
Myself I found among others a big block of fossil raindrops.
Quite astonishing that raindrops make fossils, not exactly hard bones.
Also fossil draugt cracks is not so hard to find.
[quote]You can re-orient me if I targeted the wrong thing and you can also try
the query on sci.bio.paleontology where other
views may come.
Regards,
Edward Hennessey[/quote] |
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Inyo
Guest
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| Posted: Mon Oct 13, 2008 7:40 am Post subject: Re: Is this a fossil? |
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Bjørn Sørheim <bsoerhei@nixspam.online.no> wrote in message
news:48eb4e85$1@news.broadpark.no...
[quote]The page explains it all.
Is it a fossil, or are we fooled by something else. If so, what??
http://home.online.no/~bsoerhei/geo/fossil/horneldevon/What_is_this.html
Bjørn Sørheim
[/quote]
Only the first two photos (from the top) came through to my browser. I don>t
see anything definitively organic in the Devonian-age rock specimen. The
matrix is most obviously a sandstone, as you noted in the caption to the
second image. That elongated whitish blog in upper right appears to be some
form of calcite, and the whitish specs just below it are likely the pebbles
you describe--they>re inorganic igneous contituents. I>m most familiar with
the Devonian exposures in Nevada, extremely thick accumulations of marine
carbonates, primarily, that locally produce beaucoup beautifully preserved
brachiopods and other invertebrate remains.
Fossil Plants Of The Ione Basin, California
http://members.aol.com/Waucoba5/ione/ioneproject.html |
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Number Eleven - GPEMC!
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| Posted: Mon Oct 13, 2008 2:54 pm Post subject: Re: Is this a fossil? |
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"Bjørn Sørheim" <bsoerhei@nixspam.online.no> wrote in message
news:48eb4e85$1@news.broadpark.no...
[quote]The page explains it all.
Is it a fossil, or are we fooled by something else. If so, what??
http://home.online.no/~bsoerhei/geo/fossil/horneldevon/What_is_this.html
Bjørn Sørheim
[/quote]
In your photos I see intraclasts. A mixture of small angular to sub-rounded
pebbles with what appear to be mud flakes in a very fine to fine, poorly
sorted sandstone. It appears to be fluviatile - perhaps part of an alluvial
fan. I>d be on the lookout for tool marks, flute casts, asymmetric ripples
cross beds and trough cross bedding. Bifurcated asymmetric shoreline ripples
may also be present if the flow system is on a large enough scale.
Photos #6+ show something interesting - I>m wondering what the composition
of the ultrasmooth portions is - might be a clue. I haven>t seen anything
I>d pick out as a fossil, but I>d keep my eyes open just the same...
Good luck
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