Jonathan and Bill,
I've been off the list about 6 months and might haved missed if this reference
has been discussed but it seems it might be germaine to your discussion. A
couple of weeks ago I came by an intersting article in _Palaeogeography,
Palaeoclimatiology, Palaeoecology_ entitled: "Fossil trees in ancient fluvial
channal deposits: evidence of seasonal and longer-term climatic
variability" I will copy the abstract here and send both of you the .pdf
file. (typos are mine since I am re-typing this, can't seem to copy and
paste)
Joel
Abstract.
It has been established that large numbers of certain trees can survive in the
beds of rivers of northeastern Australia were a strongly seasonal distribution
of precipitation causes extremem variations in flow on both a yearly and
longer-term basis. In these rivers, minimal flow occurs througout much of any
year and for periods of up to several years, allowing the trees to become
established and to adapt their form in order to facilitate their survival in
environments that experience periodic inundation by fast-flowing, debris-laden
water. Such trees (notably paperbark trees of the angiosperm genus Melaleuca)
adopt a relined to prostrate, downstream-trailing habit, have a
multiple-stemmed form, modified crown with weeping foliage, development of
thick, spongy bark, anchoring of roots into firm to lithified substrates
beneath the channel floor, root regeneration, and develop in flow-parallel,
linear groves. Individuals from within flow-parallel, linear groves are
preserved in situ within the alluvial deposit of the river following burial
and
death.
Four examples of in situ tree fossils within alluvial channel deposits in the
Permian of eastern Australia demonstrate that specialised riverbed plant
communities also existed at times in the geological past. These examples,
from
the Lower Permian Carmila Beds, Upper Permian Moranbah Coal Measures and
Baralaba Coal Measures of central Queensland and the Upper Permian Newcastle
Coal Measures of central New South Wales, show several of the characteristics
of trees described from modern rivers in northeastern Australia, including
preservation in closely-spaced groups. These properties, together with
independent sedimentological evidence, suggest that the Permian trees were
adapted to an environment affected by highly varible runoff, albeit ina more
temperate climatic situation than the modern Australian examples. It is
proposed that occurrences of fossil trees perserved in situ within alluvial
channel deposits may be diagnostic of environments controlled by seasonal and
longer-term variability in fluvial runoff, and hence may have value in
interpreting aspects of palaeoclimate from ancient alluvial successions."
At 08:09 PM 7/9/01 +1000, you wrote:
>
> Hi Bill
>
> I have been away for the past three weeks so my apologies for the slow
reply.
>
>
> Bill Payne wrote:
>>
>> On Tue, 12 Jun 2001 19:33:45 +1000 Jonathan Clarke
>> <jdac@alphalink.com.au> writes:
>>
>> > Please stick to the point. Your said (Thu, 07 Jun 2001 20:45:01 +1000)
>> " tree stumps commonly up to 2+ feet in diameter are virtually *never*
>> found in coal seams in the eastern US". I gave you five references, two
>> from
>> the eastern US and three from Canada that give examples of just this.
Have
>> you read them?
>
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