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From: firth@sei.cmu.edu (Robert Firth)
Newsgroups: talk.origins,sci.misc
Subject: Re: A new topic: the Sahara
Message-ID: <373@aw.sei.cmu.edu.sei.cmu.edu>
Date: Tue, 4-Nov-86 08:53:54 EST
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Posted: Tue Nov  4 08:53:54 1986
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Organization: Carnegie-Mellon University, SEI, Pgh, Pa
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Keywords: Sahara Desert
Xref: watmath talk.origins:136 sci.misc:40

Well, I lived for some years on the southern edge
of the Sahara desert.

It's not lifeless.  When it rains (every five years or so)
these beautiful plants appear out of nowhere for several
days.  Their seeds lie dormant.  Even at normal times,
there are a lot of animals - ground squirrels, lizards,
snakes, bobcats and stuff.

It's not all sand.  Large parts of it are rocky, including
a couple of mountain ranges.

It's not all dry.  There is one large inland lake (Lake Chad),
which in earlier times was much larger and surrounded by
marshland inhabited by hippo, waterfowl &c.  There are several
rivers running through it, including the Niger.

North Africa was far more productive in Roman times.  The
main reason was extensive human engineering - terracing, canals,
wells, windbreaks &c.  What destroyed it wasn't overpopulation,
it was the Arab and the goat - the one smashed everything and
the other ate everything.

Before that, the Sahara was temperate and quite damp (ca 2000 BC)
for reasons unknown to me.

Yes, the desert is spreading southweards.  The local people burn
the bush to clear the land for their crops.  This destroys the
ground cover and causes substantial erosion.  The city of Kano
(where my family lived for 5 years) was in a vast fertile region
in mediaeval times, and is now surrounded by desert and scrub.
Half the old city is ruined and deserted - it was once one of the
greatest trading centres in Africa.

sic transit gloria mundi