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Showing results for tags 'mold'.
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I found this the other day, in the cab of my pickup, while looking for ski wax. I often pick things like this out of the gravel I'm shoveling during the fall. The bulk of this material is Devonian marine rock. Bits of plant do show up now and then.
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- bucks county
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I'm getting braver and will venture that there is at least one crinoid columnal mold preserved in this formation. I'm fairly certain, however, that the other two most prominent molds are not of a crinoid. How am I doing?
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Another shoreline glacial find. Most likely lower Devonian marine delta related. The first shot shows part with scale, and inverted counterpart to the left. The last shot is of the under side of the fractured section in the photo before it.
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This is a particularly fragile type of shell, made of many fine layers, and is prone to disintegrate as these did. This rare steinkern was found on a block of matrix submerged in the Chesapeake Bay. Dimensions are for the best-exposed steinkern on the block. The entire block is 14 cm wide x 10 cm high x 5 cm deep.
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- calvert cliffs
- cast
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Please clarify for local discussion. Referencing the attached sketch: First is a coin simulating a fossil. If split at the red line, there would be 2 pieces of external mold. Correct ? or incorrect ? Second is a lens shape, like a saucer or moult of a pygidium. If split at the red line, there would be 2 pieces of external mold. Correct ? or incorrect ? Third is an egg or complete bivalve. If split at the red line, there would be 2 pieces of external mold and 1 internal mold. Correct ? or incorrect ? All 3 assume that the specimens have dissolved an left a void which if filled would be the cast. Correct ? or incorrect ? The local argument is that the pygidium moult example is 1 external mold (top) and 1 internal mold (bottom) because it is the "internal" side of the animal. I don't think that is correct. Just a local discussion needing clarification, thanks. ref: http://www.ucmp.berkeley.edu/paleo/fossilsarchive/casmol.html
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I found this crystalline calcite replacement fossil mold after breaking open the width of a 2" to 3" thick Eagle Ford limestone layer loose fragment. The rock broke along the circular arc of the fossil mold. The mold is somewhat mushroom shaped with a small inoceramus clam attached to the side. It is about 4.25" wide. A full circular arc might be more than 6 inches in diameter. The mold appears to be fragmented and hollow on the top of "mushroom shaped" side. The narrower bottom of the mold also flared out a little, but not as much as the top. I think that the thin base layer cutting at 30 degrees to the mold is an oyster shell hash layer that it was deposited with - although at the mold top the hash layer to be unusually smooth faced. Some of the calcite mushroom lip broke out on the other fragment (the 4th photo shows it upside down on the bottom). The lip was not likely to be easily recovered. So, I cut that face of the limestone fragment back from the lip so that the two can fit together where you can still see the concave fossil surface inside. I worked off the convex outer matrix of the mold and the micrite limestone matrix until there was little else left but the mold. The oyster hash (or other) layer and the small inoceramus are also attached. The limestone layers in the outcrop area has some 15mm or less tooth width sized Ptychodus and up to 12 to 20 mm long cutter shark's teeth. There were also two ammonite molds (10" to 12") preserved in similar crystalline manner. There are a few shark verts and fish/ray teeth also. The few Paleontological Society of Austin folks I showed it to at the recent meeting could only see the concave face before I had carved it out more. They would not try to guess its origin. My first inclination was that it is a large vertebrate bone fragment. That might have been just well wishing. A giant inoceramus hinge plate or other large invertebrate (like ammonite or nautiloid) interior mold seems more likely. Any educated guesses? Thanks in advance for your time.
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- eagle ford
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Is this one more recognizable ? It occurred to me that a lot of people may not know what the real structure of these is. Figured it wouldn't hurt to make sure I'm not one of them
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From the album: Texas Finds
Scientific Name: Crinoid? Found: North Central Texas Shoreline Date Found: 6.3.13 Formation: Eagle Ford Size: 6mm x 44mm Comment: Notice the small circular mold / impression. This piece of matrix has several of these small and large. Could these be the base of Crinoids? Any comments appreciated!-
- Crinoid
- Eagle Ford
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From the album: Texas Finds
Scientific Name: Crinoid? Found: North Central Texas Shoreline Date Found: 6.3.13 Formation: Eagle Ford Size: 38mm x 38mm Comment: Could this be the base of the Crinoid? There is a small cord like structure attached to this. Any comments appreciated!-
- Crinoid Base
- Eagle Ford
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