A makhtesh… a what? A makhtesh!

As we continue in my series of posts on the beautiful Negev, we arrive at the point where we need a short lesson in geology.  I know, not all of us love geology, so I promise a short and easy-to-understand explanation.

The Negev cannot be fully appreciated without an understanding of the unique and fascinating geological processes by which it was shaped and formed.

One of the  extraordinary landforms of the Negev is the makhtesh, of which there are 3 in close proximity, all very similar in their characteristics and all formed in essentially the same way. The geology lesson begins here, as we try to understand the makhtesh

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A makhtesh is sometimes translated as a ‘crater’ but that is misleading, as craters are usually created by volcanic eruptions or meteorites hitting the Earth’s crust.  A makhtesh is none of that… it is a  geological formation unique to the Negev and the Sinai, created by erosion, the slow process by which soil and rock is removed by wind or water flow, then transported and deposited somewhere else.

It all started hundreds of millions of years ago, when the Earth’s crust was repeatedly covered with layers of sediments.   For millions of years,  these sediments would be of tiny grains  of sand, made up of quartz and feldspar and other minerals  eroded away from massive granite mountains that had been created by magma emerging to the surface of the Earth.  These sand deposits eventually hardened and became different types of sandstone.

Then, with shifts in the tectonic plates, the area would be covered by an ancient ocean for millions of years, and  skeletons and shells of billions of marine creatures would sink to the sea floor, laying layers of calcium carbonate (CaCO3 for those chemistry inclined), eventually creating limestone and chalk.

This geological process repeated itself over and over again. Hard limestone layers and soft sandstone layers, accumulating on top of each other over the millenia.

Stay with me, it gets better.

The Negev (and most of the areas of Europe and the Middle East) was covered by an ancient body of water called the Tethys Sea about 100 million years ago. As it began to  recede,  immense geological pressures started pushing and  shoving the terrain into folds, eventually becoming mountain ranges that  all extend in the same direction,  from the southwest to the northeast.  These ranges are clearly visible today and reach from the Sinai to the southern Dead Sea.

רשים מכתש1As the folds, now mountain ranges,  began to rise, deep cracks were created in the top hard limestone.

Rainfall found its way into these cracks, and over time made them deeper. As the cracks became bigger, the water reached the deeper sandstone layers and began to erode the sand away.תרשים מכתש

The harder top layer of limestone eroded slower, the softer sandstone underneath eroded faster, and over several million years, a large cavity in the ridge formed,  and voila… a makhtesh!

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The Makhtesh HaKatan is a beautiful site, an almost perfect bowl,  carved into  the colorful sandstone of the Negev. It is still drained by only one stream and has attained a balance of sorts,  not growing and not shrinking.

It is the smaller of the three makhteshim in the Negev and the first you should visit in order to fully understand this geological phenomenon.

Sitting on the edge of this beauty is quite breathtaking.

This makhtesh is only accessible by foot and walking its many hiking trails is an amazing experience.  The sandstone walls are gorgeous, painted different colors by the amount of oxides in the sandstone; iron makes red, copper makes green, manganese makes orange… there are also browns and purples and whites and yellows, quite a kaleidoscope of colors.

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We will visit the other two makhteshim and go on other Negev adventures in my upcoming posts.

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