However apparently ( and I havent seen them) many of the fissures have mega fauna bones choked along the seams. Quite a puzzle. I must investigate.
seasmith wrote:“ Field description of the veins in the study area:
The veins are predominantly vertical. In some places they are run in the same direction, in other places multiple directions exist, or even a random direction.
The veins seem to be restricted to a geologic unit known as the Chadron Formation, and pinch out with stratigraphic ascent before they reach the overlying Brule Formation.
Chalcedony, a cryptocrystalline form of quartz, is the most common vein material. Because chalcedony is significantly harder than the surrounding sediment the veins stand out as small ridges.
The veins are zoned, with darker chalcedony at the margin, and lighter chalcedony towards the middle. The larger veins also show a core of calcite.
The veins are note evenly distributed. They occur in distinct areas or patches. In addition, the patches seem to be related to the faults. One patch occurs at the tip of a larger fault. Others seem to truncate against faults.
The larger veins often show evidence of slip along the vein, suggesting a continuum between the two structures. Interestingly, the slip often involves a vein shortening component (they look like small thrusts). However, considering the vertical orientation of the veins this is consistent with horizontal extension.
The veins often come in stepped (en echelon) geometries.
Tips of overlapping adjacent, but parallel veins can often be seen curving towards each other. These structures are called tip curls.
Sparky » Sun Jul 25, 2010 1:41 pm
Hello Sparky: I'm a fake geologist. I have seen limestone that appears melted.
Thanks....i have seen similar formations somewhere, but can't remember where...would like to find out if these cups have a bottom or are tubes..
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