>You had said earlier that the Mongolian sandstones contained boulders. Were
>you referring to what the authors of the January Geology article said were
>carbonate concretions? I didn't find any other reference to boulders or
>cobbles in the article.
The article mentioned (and I said) cobbles (and pebbles) too large to have
been transported by wind. Specifically:
"The pebbles and cobbles within some of the sand bodies of this facies were
clearly derived from beyond the margins of the dune field. The
conglomerate at tehe top of the section indicates that the dunes...were
adjacent to a tectonic highland; large clasts in the structureless
sandstone were transported into the dune field by sediment gravity flows
originating in the highland." (Geology 26:29)
This would indicate an origin by subaqueous debris flow is not only
possible, but likely.
Art
http://chadwicka.swau.edu