[Terrapreta] Pottery Shards and Terra Preta

[Michael Bailes]

[image:
http://www.css.cornell.edu/faculty/thies/lab/images/research/tp4a.jpg]

Here pottery shards litter the ground. At one of the site's two excavations,
the broken bits stick out from the earthen walls of a large square pit. The
layers of protruding pottery are so tight and thick they look almost like
wall coverings.
http://discovermagazine.com/2007/apr/black-gold-of-the-amazon/article_view?b_start:int=2&-C=


*Cultural* *mosaic*
>
> Climbing to the top of Ibibaté, a forested loma (mound) 18 meters higher
> than the surrounding savanna, Erickson comes to a bare patch of earth
> created by a fallen tree. Bending over the uncovered ground, he points out
> the dark, almost black soil, which is filled with fragments of pottery.
>
Several pieces of pot rim are visible, along with the leg of a vessel shaped
> like a human foot. Both the richness of the soil and the abundance of the
> potsherds are typical, in Erickson's view. "Many of the lomas are almost
> nothing but enormous heaps of sherds," he says. "I've never seen anything
> like it—10, 20, 30 feet of sherds"
>
http://www.sas.upenn.edu/~cerickso/baures/Mann2.html

The firing of the potteries occur in open atmosphere (Fig.
6<http://acta.inpa.gov.br/fasciculos/34-3/img/n3a04f06.jpg>),
> possibly in the same primitive way as the actual Indians and caboclos still
> do. The firing temperature didn't exceed 600 ºC, as demonstrated by partial
> dehydroxylation of clay material and the formation of maghemite. This phase
> formed *the ceramic minerals:* dehydroxylation of clay giving rise to
> burned clay, maghemite and recrystallization of anatase. Maghemite promotes
> the slightly brown to red color of the potteries.
> . . .
> Chemical elements such P, Mg, Ca, Mn, Ba, Zn, Pb, etc. are fixed partly
> and concentrated in the organic humus of ABE soils and possibly is partly
> absorved in the ceramic fragments, contributing to formation of phosphates
> and Mn oxyhydroxides in less extension.
>
http://acta.inpa.gov.br/fasciculos/34-3/BODY/v34n3a04.html

Rich in humus, pieces of pre-Columbian unfired clay pottery, and black
> carbon, it's like a "microbial reef" that promotes and sustains mycorrhizae
> growth and other beneficial microbes, and it has been shown to retain its
> fertility for thousands of years.


. . .

> South American *terra preta* soils are also full of pieces (sherds) of
> unfired pottery. It is generally believed that the pottery was introduced
> into the soil much as modern growers add perlite or sand to potting mix, as
> a way of keeping the soil from baking completely tight under the tropical
> sun before a cover of vegetation could grow over it. Much is made of these
> sherds as "proof" that *terra preta* deposits are really prehistoric trash
> piles, but Charles C. Mann asserts there are indications that much of this
> pottery was actually made specifically for incorporation into the soil.
>


http://www.championtrees.org/topsoil/TerraPreta.htm

The above described minerals and organic substances led to identify the
> following materials as raw materials for the ceramics:
>
> 1) clay material derived from weathering (saprolite/mottling zone) of fine
> crystalline and less frequent sedimentary rocks (indicated by clay-derived
> minerals and iron oxy-hydroxides, anatase and quartz );
>
> 2) fresh crystalline rocks crushed (feldspars, quartz and rock fragments);
>
>
> 3) organic materials (cauixi and burned cariapé).
>

http://www.scielo.br/scielo.php?pid=S0044-59672004000200004&script=sci_arttext
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