<http://www.terradaily.com/images/great-green-wall-sahara-africa-desert-bg.jpg>
Fixing sand dunes through afforestation is cost effective.
by Staff Writers
Widoy Thiengoly, Senegal (AFP) Oct 29, 2008
The idea was simple, ambitious and eye-catching: to counter the threat of creeping desertification in Africa through a Great Green Wall of trees spanning the continent from Senegal in the west to Djibouti in the Horn of Africa in the east.

http://www.terradaily.com/reports/Africas_anti-desert_green_wall_starts_small_in_Senegal_999.html
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In the link to message above you can see an idea which is far more uplifting than one from south western USA for another kind of wall – – a fence of masonry and metal between US and Mexico to discourage economic migrants heading north.

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