-------------- Original message ----------------------
From: cavera...@aol.com
> But how do the red clays of the Florida and SW Georgia karst fit in? I
> don't think these clays are massively thick. But more interestingly, unless
> they
> are derived from elsewhere, I don't there was much of anything other than
> limestone of various ages present in this region.
It has always been my understanding (admittedly marginally based) that just
because a soil is "red" does not make it "terra rossa". If you've ever seen any
real terra rossa you will recognize a definite difference--it is REALLY red. My
"Glossary of Geographical Terms" (35 years out of date now and of British
manufacture and some European bias) offers the following:
Terra rossa (Italian)
/Webster/, The red-colored residue from the weathering and partial soulution of
certain rocks, especially limestone.
Mill, /Dict./ Terra Tossa. Red earth (Italy). The name has been extended to
other regions.
/Soils and Men/, 1938. ;The term has been widely applied to red soils developed
under the warm-temperate Mediterranean type of climate, marked by wet and dry
seasons. Many writers have preferred to limit Terra Rossa to soils developed on
Limestone, while some would have it include any red soil in a Mediterranean
climate....At present its only distinction lies in it's color.'(p. 991)
Robinson, G. W., 1932, /Soils/, London: Murby, 'Terra rossa is a name given to
red soil which oddurs commonly in the countries bordering the Mediterranean
Sea. Typically it is associated with linestone...we follow A. Reifenberg in
restricting the term to such soils.'(p. 287)
Jacks, 1954. Red bbase-saturated clayey soil formed from hard limestone in the
Mediterranean climate.
However:
Terra roxa (Brazil: Portuguese) pr. ro-shah.
James, 1959. �mong the soils of the Paran� Plateau, the /terra roxa/ (lit.
purple soil) formed on the outcrops of the diabase...is a deep, porous soil
containing considerable humus, which can be easily recognized by its dark
reddish purple color--when wet it becomes so slippery and sticky that travel is
very difficult, and in dry weather it gives off a powdery red dust which stains
everything'(p. 474)
(Note: Diabase is an igneous rock, not at all Limestone. Still, the soil was
red.)
A Google search yielded:
ORIGIN OF ASSOCIATED TERRA ROSSA AND KARST BY REPLACEMENT
Authigenic terra rossa clay partly replaces limestone across a 9-cm-wide
metasomatic reaction zone several feet below the earth's surface at
Bloomington, ...
<gsa.confex.com/gsa/2005AM/finalprogram/abstract_90146.htm>
Genesis of a Terra Rossa soil over marble and the influence of a ...
The genesis of Terra Rossa soils is still a matter of controversy. The two
leading theories are that (1) the soil is derived from the insoluble residue of
...
<www.regional.org.au/au/asssi/supersoil2004/s11/poster/1607_fosterj.htm>
Colloidal Silicic Acid in Terra Rossa
ACCORDING to Reifenberg1 colloidal silicic acid has an important role in the
development of terra rossa. In order to substantiate this theory the existence
...
<www.nature.com/nature/journal/v194/n4826/abs/194409a0.html>
SOURCES OF SILICATE DUST IN TERRA ROSSA SOILS AND SURFICIAL ...
Results show good correspondence between the clayey Terra Rossa soil horizons
and nearby lunette deposits, indicating that the soil is largely derived from
...
<gsa.confex.com/gsa/inqu/finalprogram/abstract_54373.htm>
terra rossa (soil) -- Encyclopaedia Britannica
A distinctive feature of Montenegro is the accumulations of terra rossa in its
coastal area. This red soil, a product of the weathering of dolomite and ...
<www.britannica.com/eb/topic-588154/terra-rossa>
And many more. Good reading....
Wikipedia did not appear in the first 4 pages of hits.
I think the jury is still out,
--Ediger
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