Re: Fastovsky vs Archibald

[Phil Bigelow <bigelowp@juno.com>]

In some H.C. sections that I have mapped in eastern MT, I have seen
single (UNnested) paleochannels 60 meters wide.  Meaning that I can
follow the outline of the channel bottom its entire width.  Single
channel, no crosscutting.  In another area, I have seen a complete
fluvial meander sequence (probably of the same river), with channel,
point bar, levee of almost 90 meters width.

There were multiple large rivers that layed down the H.C. beds, and most
stratigraphic evidence suggests that they were Missouri R. size or
bigger.

The sedimentation rate off of the Larimide uplift was unbelievably huge
in eastern Montana.  Flooding appears to have been a vastly more common
occurrence than was desiccation.  Except in certain rare cases at its
top, the Hell Creek Formation was well drained (it didn't have much
swampy ground).

<pb>
--


On Sat, 25 Jun 2005 13:32:41 -0600 frank bliss <frank@blissnet.com>
writes:
> I am not sure where I heard that 10my number.  I knew that the sand 
> was 
> being dumped by the truckload based on local observations of things 
> 
> like soft sediment deformation but 2my is really fast for 700 feet 
> of 
> section.  Cool.  The streams were literally a conveyor belt from 
> source 
> to sink.
> Frank Bliss
> MS Biostratigraphy
> Weston, Wyoming
> On Jun 25, 2005, at 5:51 AM, Phil Bigelow wrote:
> 
> >
> >
> > On Sat, 25 Jun 2005 09:50:28 -0600 frank bliss 
> <frank@blissnet.com>
> > writes:
> >
> >> Thus a dry season at a minimum and maybe even a drought
> >> or
> >> two mixed in over the 10 million years it took to accumulate the
> >> section.
> >
> >
> > I have read (from diverse sources) that it was closer to 2 - 3 my
> > duration, max.
> >
> > <pb>
> > --
> >
> >
> >
> >
> >
> 
> 
>