Thorny questions

Andrew K. Rindsberg arindsberg at GSA.STATE.AL.US
Mon May 15 12:32:11 CDT 2000


Data are more useful than deconstruction in this case, although Pierre
Deleporte's concerns are legitimate. Here are some possibly pertinent dat=
a
for Richard Brown:

1. The Pleistocene fossil record of the Black Belt is meager, but elephan=
ts,
ground sloths, and horses -- i.e., both browsers and grazers -- were
present. Dating is poor, as most of the bones were found in alluvium of
uncertain age, and some may be reworked from older deposits.

2. Although the original plant cover has been highly modified, the areas =
now
mantled in black soil (hence the name 'Black Belt') correspond to grassla=
nds
surveyed about 1816 before white settlement. Areas with dark brown soil
correspond to forest in 1816. Grasslands and forests may have been modifi=
ed
by the native population, but the presence of Pleistocene horse remains
strongly suggests that grasslands were already present then.

3. Based on geomorphic and palynologic evidence, the climate of the
Southeastern US seems to have been relatively wet and cool during ice max=
ima
(supporting spruce and hemlock in the uplands), and relatively dry and ho=
t
during ice minima (and during La Ni=F1a!). The Southeast is partly within=
 the
Northern Hemisphere's desert belt, and without the Gulf of Mexico supplyi=
ng
moisture by evaporation, the region would be much drier than it is at
present. Anything that prevents winds flowing from the south will also te=
nd
to dry out the Southeast.

4. Currently, the Black Belt is maintained as mixed pasture and forest, a=
nd
is slightly warmer and drier than surrounding areas that are mostly woode=
d.
To some degree, the grassland makes its own climate.

5. Osage orange makes good bows, so it would be reasonable for a migratin=
g
tribe to take seeds along, though 'reasonable' cannot be taken as 'proved=
'.
Some of the Southeastern tribes believed that they migrated from the west=
,
while others thought of themselves as indigenous. For various reasons, th=
ese
traditions are not wholly reliable. Based on archaeologic evidence,
population fell sharply about AD 1450, and probably again after the DeSot=
o
expedition introduced European diseases in the early 1500's. Skeletal and
other evidence suggests that some populations were replaced. So it is fai=
rly
certain that tribes moved extensively well after the invention of the bow=
,
and hence might have brought osage orange while traveling from the west.

6. I have often wondered why osage oranges have fruit with milky sap. The
local plums have thorns and tasty fruit, as if to attract animals such as
bears to avoid harming the tree while eating the fruit (and then spread t=
he
seeds nearby; the fruit is laxative). What kind of animal would eat an os=
age
orange? I suppose this fruit could transport its seeds by rolling; the
fruits are large and round. Do they float? Does the modern distribution o=
f
osage orange correspond to the historical territories of particular tribe=
s?

It would be good to ask palynologists whether they have Pleistocene and
later records of osage orange pollen in Mississippi and Alabama. It would
also be worthwhile to investigate the degree to which the Black Belt flor=
a
is endemic, if at all. There are some endemic crayfish that show adaptati=
ons
to a dry climate.

If you don't have them already, Richard, I have references to support ite=
ms
1 to 4. Item 5 can be supported as well, but I don't have references hand=
y.
Item 6 is wild speculation, for which I apologize to Pierre. ;-) I realiz=
e
that this doesn't answer the most pressing 'thorny questions', but at lea=
st
it puts them on firmer ground.

Andrew K. Rindsberg

Geological Survey of Alabama
P.O. Box 869999
Tuscaloosa, AL 35486-6999
USA




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