How the White and Black
Desert were formed.
The white and black deserts of the Western Desert in Egypt did not just form
themselves. In fact, it took over 70 million years to create what we have today. Although
the deserts are very close to each other, both deserts have different cycles they went
through in order to become what they are today.
The white desert started to be formed about 70 million years ago. At that time, the
western desert was completely under deep water. Eventually, bones and carcasses of
fishes and animals dissolved into the water. Many million years later the water
evaporated from the western desert region. The dissolved bones and carcasses fell to the
bottom and cemented together. When all these bones and carcasses stuck together, they
created limestone. The dissolved bones and carcasses are white therefore making the
color of the rock white.
At the same time as the white desert, the black desert was being formed. The
black desert also started in water, but this time in the bays and deltas. When the river
pushed rocks and sand out into the ocean, the rocks sank first in the delta area. Many
million years later, the water evaporated leaving the delta-like areas there. The big rocks
that had been deposited next cemented together and formed the sandstone. This sandstone
is on top of the limestone because the limestone was formed in deep sea and as the water
level decreased and moved towards Europe, the delta kept changing. Since the delta kept
moving, new sandstone was formed on top of the limestone.
Now the part that made this desert called the black desert is very unique. After
the water had gone, lava came pouring out of a rift. This narrow lava flow traveled far.
When the lava stopped flowing, a black layer of basalt had covered the sandstone. After
many years of erosion, a layer of sandstone blew away leaving small hills with black tops
from the basalt. The black rocks were never eroded because they were a lot heavier than
the sandstone. Some of the black rocks are also rolled down these small hills only
because they have been blown down.
Another interesting thing is that the black desert is above the white desert. This
was caused because the sandstone in the white desert was eroded leaving only the hard
limestone layer underneath. The black desert, on the other hand, was not eroded so the
layer of sandstone that is above the limestone layer is still there.
Throughout the millions of years there have been many eroding agents in the
black and white deserts. The main eroding agent was wind. Wind eroded rocks. Another
helpful agent was the sand. The sand was carried by the air and brushed against rock
repeatedly causing the rocks to erode. Since the wind cannot pickup the sand particles
very high, the rocks only rub on the bottom of the rock structures. This constant rubbing
on the bottom of the rock structures creates mushroom like rocks.
In addition to those eroding agents, there are more today. Humans are a big
eroding agent. People often pick up rocks in the desert and toss them back out. Believe it
or not, this is a very common eroding agent.
So as you may now know, the black and white Western desert of Egypt did not
make itself. It went through many years, many different circumstances and many eroding
agents to make it how it is today.