> "This and similar fossil 'forests' must be taken into account in
>reconstructing the paleoecology of the Navajo. it is possible the scattered
>ponds and small groves of trees provided food and perches for the pterosaurs
>known to have left trackways in nearby localities."
>"Silicified wood fragments as much as 20 cm. in diameter are widespread in
>outcrops of the Triassic-Juraswsic Navajo Sandstone near Moab, Utah. The
wood
>is typically found in indistinctly crossbedded sandstone peripheral to thin,
>discontinuous carbonate beds. some trunks are in nearly vertical position
>suggesting in situ preservation. Smooth, fluted surfaces on some fragments
>indicate abrasion before burial.
> "Diverse tubular and cylindrical structures, typically in diameter are
>also abundant in the Navajo. They occur just below horizontal truncation
>planes which separate sets of crossbeds. Crossbedding is indistinct below
the
>truncation planes, and distinct and undisturbed above. Tubes are composed of
>an outer sheath of well-cemented sand surrounding a core of calcite spar;
>cylindrical features consist entirely of sand. These structures have many
>similarities with root casts in Holocene dunes at Arches National Park, near
>Moab, and have important implications concerning depositional environments of
>the Navajo Sandstone."
Interesting stuff. I predict a careful examination will demonstrate, as it
did in Yellowstone that the trunks are transported, that the limestone will
reveal fossils incompatible with sanddunes, and that the root casts are
truncated abruptly.
Art
http://chadwicka.swau.edu