“Blessed are you, G-d, King of the Universe, who creates the light of fire.”

This is one of the blessings recited at the conclusion of Shabbat during havdalah. According to Jewish tradition, at the conclusion of the first Shabbat, Adam, the first man, lit the first fire.  Story goes that Adam after sinning and being exiled from the garden of Eden, became afraid as Shabbat came to a close. Only the       day before, on Friday afternoon, he sinned by eating from the Tree of Good and Evil. G-d had said that on the day that Adam ate from the tree, Adam would die. Adam thought to himself, “Maybe this is the way it is all going to end. Shabbat is coming to a close, the light is disappearing.” But it is  human to try to stay alive and  Adam becomes afraid.  He turns to G-d for help, and G-d shows Adam how to strike two flint stones together to create the light of fire.

Interesting expression:  “the light of fire”.  Seems that one or the other would be sufficient.  Why both?

Fire represents the bodily need for warmth and protection.  Fire is passionate.  Light illuminates and provides spiritual comfort.  Light is soft.

But I want to take a minute to examine another part of the story – flint.  Flint is an interesting material.  Despite its otherworldly appearance which could lead one to think that it is an igneous rock coming from the depth of the earth’s core, it is  actually sedimentary.  Flint forms under almost exactly the same conditions as chalk.  (See my previous post, Chalk Talk.)  It forms from the compaction of skeletons of the same sea creatures in the same deep water.  You can find seams of flint layers in chalk.  In Israel this is apparent in many places including the       Bell Caves in Beit Guvrin, Herodian water cisterns, and Rosh HaNikra.

It was very surprising to me when I learned that beautiful, pure white, soft, uniform, thick chalk and dark, variegated, hard flint were actually formed under almost the same conditions.  It kind of reminds me of the light/fire dichotomy.

So, when does chalk form and when does flint form?

Sea creatures’ skeletons which form these two types of rock are mainly composed of CaCO3 (Calcium Carbonate) with traces of other chemicals, most notably Silaca (SiO2).  Because, the silaca is such a minor part of the sea creature’s make-up, you do not see it amongst the overwhelming amount of CaCO3 in the resulting rock       layer under normal conditions.

However, if the sea becomes slightly more acidic, then the basic Calcium Carbonate is dissolved and not deposited as sediment on the bottom of the sea.  In that situation, only the silica (and other trace chemicals) sink to the bottom of the ocean.  These concentrated silicates upon lithification become flint.

And what would cause a sea to suddenly become more acidic?  Here is where geothermodynamics comes into play.  Upon eruption of volcanoes, elements from the earth’s core are oozed into the oceans.  Under these conditions, the ocean waters become more acidic.  So, it is pretty amazing that we can measure volcanic activity in the geologic past by looking at rock layers today.  

To follow the whole thread from volcano to flint:  volcano erupts, elements from the earth’s core ooze into ocean making it more acidic, acid ocean water dissolves CaCO3 leaving concentrated silica to settle to bottom, silica is lithified forming flint layer, G-d gives Adam flint and know-how to make fire/light, humanity is given hope for a new week!

“Blessed are you, G-d, King of the Universe, who creates the light of fire.”
Everyone should have a good week full of light and fire!

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