>I have on my desk a chunk of a Pennsylvanian 'rythmite' from a classical
>locality in Michigan. Only problem is there is a vertical Neuropteran
>frond that crosses two complete sets of so-called tidal cycles. Either
>there is some other explanation for the accumulation of tidal rhythmites or
>the delicate lace-like frond remained intact and extended vertically from
>the sedimentary surface (perpendicular to bedding) while the tidal cycle
>sediments accumulated around it and eventually buried it after two months.
Are these cycles the fortnight cycles? If so, there is no problem. Leaves
today last quite a long time in lakes and streams prior to their destruction.
"Spicer noted that leaves in modern depositional settings can develop an
iron encrustation within a few weeks of their entry into a stream
depositional system. Iron-bacteria in particular Spherotilus sp., were
present on leaves examined from England, and were proposed as the primary
means of iron encrustation." ~ K. A. Dunn, et al, "Enhancement of Leaf
Fossilization Potential by Bacterial Biofilms," Geology
25(1997):12:119-1222, p. 1121
Notice that this is over several weeks!
glenn
Adam, Apes and Anthropology
Foundation, Fall and Flood
& lots of creation/evolution information
http://www.isource.net/~grmorton/dmd.htm