Erosion crater
The erosion craters ( Hebrew מכתש machtesch , plural:מכתשים Makeshim ) of the Negev desert in Israel are geological phenomena that are unique worldwide. The Negev is home to five such craters. Two more are located in the neighboring Sinai in Egypt , which shares many characteristics with the Negev. The Negev's craters are (by size):
- Makesh Ramon
- Machtesh Gadol (Machtesh Chatira)
- Machtesh Katan (Machtesh Chazera)
- the two tiny Machtesh Arif .
These craters are not volcanic craters , but erosion craters. Because of the peculiarity of this geological appearance, the Hebrew term "powerhish", which means something like mortar, mortar, has become common in geological terminology.
Formation of the erosion craters (Negev desert)
- Sand is deposited in the region by primeval rivers.
- An ancient sea covers the area and deposits hard limestone . The sand below turns into sandstone .
- About 90 million years ago the area folds. There are several folds in a northeast-southwest direction. The long folds ( anticlines ) are asymmetrical, the south-eastern flank slopes steeply.
- These elongated mountain ranges rise out of the sea as islands.
- The islands are eroding and the hard limestone domes are being removed. The soft sandstone is exposed to erosion and is also removed. The island flattens out.
- The sea retreated 30 million years ago. A height gradient is created , which releases the soft sandstone formations of the erosion.
- The Jordan Rift began to open up about 6 million years ago . Since the Jordan Rift becomes deeper than the Mediterranean , the altitude gradient becomes even sharper, so that the potential energy of the water is increased again. The streams no longer flow west to the Mediterranean, but east to the Jordan Rift into the Dead Sea and have a higher erosive force.
- Where the limestone dome has not been removed, the sandstone is still protected.
The result is a unique “ geological window ” that gives an insight into the geology of millions of years.
Web links
Commons : Erosion Crater - Collection of images, videos, and audio files
