April 25, 2019 Thursday
Bedtime Story
The Mystery of the Great Lakes
Last night we were left wondering as to the
source of the freshwater in the Great Lakes of North America.
Could it be that some mysterious feeding
river flowing down the icy slopes of some Himalayan mountain is constantly
inundating these lakes?
Or perhaps there might be some invisible
groundwater springs that is unknown to all taking care of these lakes?
The answer is none of the above is correct
in any meaningful way.
You will be surprised to know that of these
three factors it is only the precipitation that contributes marginally to these
lakes and at the best replace the water that is lost by evaporation but no more
than that.
There is nothing of substance that can be
said to be the source for the freshwater of these massive naturally occurring
water bodies.
So the mystery deepens.
The answer to this mystery lies not in the
present but in the distant past; not any historical and cultural past but
geological past that goes back more than a billion years (remember that our
planet is a mere 4.6 billion years old therefore 1 billion becomes a
substantial part of it).
Actually our entire solar system is pretty
much that many years old as is our planet and when I say “pretty much that many
years old” you have to cautious in interpreting it.
When we are talking about time spans that
are billions of years “pretty much same” would include a difference of 50 to
200 million years.
This is an incredibly long time for a human
perspective if you were to consider that the entire Order of Primates is merely
65 to 80 million years old with the earliest primate barely resembling modern
day lemurs might have first evolved 80 million years ago.
The geological condition for the formation
of these Great Lakes was laid almost 1200 million years ago by movement of
tectonic plates but the water that filled these massive geological cavities
came at the end of the last glacial period about 12,000 years ago.
More specifically this glaciation period
for North America is known as the Wisconsin glaciation that extended from
75,000 years ago to 11,000 years ago.
These lakes formed at the rim of the
receding ice as the enormous mass of the continental ice sheet retreated.
The glaciers not only provided the
freshwater that we see know but their scouring also led to carving out of the
basins for these lakes albeit very rough and uneven.
Such lakes that are formed due to the
activity of glaciers are generalized as glacial lakes and most of them that are
present today are found in Asia, Europe and North America.
The area on this planet which will see the
most formation of glacial lakes in the coming centuries as a result of
continuing deglaciation would be the Southern Tibetan Plateau.
(2.) At Sea on the Atlantic on and off the
East Coast of North America – a substantial amount of warfare that took place
in 1812 was of Naval in nature.
Stay tuned to the voice of an
average story storytelling chimpanzee or login at http://panarrans.blogspot.com
Good night Mon Ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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