Anasibirites Bed Cross Section

The images on this page show a cross section of the anasibirites beds

   Grid Reference
This picture shows the grid reference from the map, and the outline of the rock and cut.

Actual Rock
This is a view of the top of the section, the top of the anasibirites beds, the cut was made through the shell of one of the visible specimens of Anasibirites, ammonoid #33, 115mm Diameter.  The cut goes through a smaller ammonoid partially visible just north of, and partially under, #33, and barely through a Wasatchites, just north of and under it (it has an arrow drawn on it).


Cross Section of the Anasibirites Beds.

Click the image for a larger view (about 2x actual size), without all the annotation (255 Kb)

Ammonoids are outlined in black.  The rocks were collected and cut, then an acetate peel was taken.  I soaked the cut surfaces in 5% hydrochloric acid  for about 20 seconds then flooded the surface with acetone and applied a cut sheet of cellulose acetate, this could be peeled off in a few minutes.  The acetate peels were then scanned on a flat bed scanner.

The spaces in between the cut sections were filled with soft fissle shale, so they could not be sectioned with an acetate peel.

The thicknesses shown on the right were measured in the field, and adjusted on the image.  The location of the base of the Anasibirites Bed was located and measured from the acetate peel and field data (an older section showed it 65-105mm lower, but after new evidence from the field, the base of the anasibirites beds is revised upwards in between the two middle sections).  Only the top 150-200mm or so of the Meekoceras beds were sectioned just so I could find the base of the Anasibirites Beds.

The bottom three sections came from a location about 200 meters north of the mapped area where they were easier to obtain.  The orientation of the cut lines up fairly close (not exact).

Thanks go to Gene Boardman of U-Dig Fossils for a great job of cutting the rocks for me.

ammonoid d

detailed view at ammonoid marked 'd' Wasatchites (about 3x)

Ammonoid a

detailed view at ammonoid marked 'a' ?Koninckites (now assigned to Clypeoceras) (about 3x)

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