With school in session around the country, millions of students are back in class learning about the world around them. Today’s technology is transforming the classroom, with inter-active touchscreen tablet PCs and Kindles sprouting up everywhere. A world removed from our grandparents one-room school with a coal-fired stove and rudimentary blackboard.
But a part of that pioneering legacy steadfastly refuses to be replaced. The ever-versatile, old-fashioned piece of chalk still remains as an energy-free, highly-versatile, affordable tool for teachers.
And with good reason. According to our archaeologists, we’ve been using natural chalk as a communications tool since the dawn of history. One look at our ancestors prolific prehistoric cave paintings and hieroglyphics tells the tale of our earliest educators efforts at knowledge transfer.
The fascinating thing is, chalk powder is actually composed of billions of micro-fossils called coccoliths. These are tiny skeletal plates which once covered living cellular organisms called plankton. When the plankton organism dies, the cell degrades, leaving behind the hard calcitic skeletal plates. Coccoliths are very small, even by plankton standards, and are called nano-fossils, shown here with an electron microscope.
Chalk originates from limestone rock deposits which were formed between 100 million and 60 million years ago when global temperatures and sea levels were much higher than today. The chalk deposits formed in sea beds where high numbers of coccolith plates could accumulate as pure sediments, undiluted by mud or sandy soil washed in from the continents. These micro-sediments take on strikingly delicate shapes as seen here.
As our inland seas retreated, they left behind layers of sedimentary mud which hardened into rocky chalk strata, filled with micro-fossils and skeletons of marine life. These muddy layers of calcitic sediments eventually become fossilized, preserving a diverse geological history in the process.
Today, chalk has a great many uses in our society, far beyond the classroom. For example, when chalk is heated, it becomes lime, which is used to make steel, aluminum, glass, sugar, cement and fertilizer. Yes, those nano-fossils are still playing an important role, even now, 80 million years later.
So the next time you see your child master a math problem on the chalkboard during parent-day at school, tell them about the tiny little creatures, living eons ago, which made it all possible.
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