[Terrapreta] Praire is natures way of making terra preta.

[David Yarrow]

much of the upper midwest has undergone three successive eras of glaciation, which has laid down three types of deposits.

first are direct deposits drooped from the ice sheets. these tend to contain the coarsest size particles -- even boulders.  some areas had obstacles to water flows which formed large lakes, which then left lacustrine sediments on their bottoms.  for example, between albany and schenectady and north to saratoga is the pine bush -- a rare area of infertile sand dunes left on the bottom of post-glacial lake albany.  the principal pine bush tree is pitch pine, which grows in the nutrient-poor sands and is frequently regenerated by wildfire, so a pitch pine of 100 years is an elder for its species and ecotone.

second are alluvial outwash deposits carried and dropped by the rivers of melting glacial ice.  due to the varying speed of the meltwaters, these deposits often tend to sort the particles out by size and density.  these alluvial deposits include sandbars and clay beds

third are wind-borne deposits (loess), which were carried long distances.  glacial eras are characterized by very high velocity winds -- up to 200 mph, as i recall (similarly in antarctica today) -- blowing across landscapes often bare of vegetation.  volcanoes are also more active in glacial eras, spewing ash into the atmosphere and carried by these winds.  these deposits tend to be fine textured with small particle sizes.

taken together, glaciation is a geological era of rapid and widespread soil formation.  but these soils are only minerals, and a longer post-glacial period is needed to create truly fertile soils enriched with abundant biomass.

areas such as the australian outback have not had any such geological era of glaciation or volcanism to renew their mineral supplies in perhaps 50 million years.  without available, usable minerals, these soils can't support much vegetation.  without vegetation, they can't hold water, or form a magnetic membrane to lift water to or near the surface.  last year i saw soils in western india that are deserts suffering from a similar geological fate of ancient exhaustion and depletion.

David Yarrow
"If yer not forest, yer against us."
Turtle EyeLand Sanctuary
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  ----- Original Message ----- 
  From: joe ferguson 
  To: lou gold ; terrapreta at bioenergylists.org 
  Cc: David Yarrow 
  Sent: Saturday, September 01, 2007 5:26 PM
  Subject: Re: [Terrapreta] Praire is natures way of making terra preta.


  Two points:
      I recall from somewhere in my ancient education that many areas of the US Midwest have deep loess soils accreted from windblown particles eroded from the mountains to the west (upwind.)
      And I recall reading a recent article about current work in perennial crops, such as wheat, and what they can do for restoring the soil.  I just googled for a reference to the specific article, but to no avail.  But I did get lots of hits on the subject.

  Joe

  lou gold wrote: 
    Thank you, David. I'll chalk it up to my mis-education as a youth in Illinois. Yes, I really was taught this long ago. It seems similar (as you suggest) to the widespread teaching that there could not have been developed civilizations in the Amazon "due to poor soils." 
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