A makhtesh ( he, מַכְתֵּשׁ (), Hebrew plural: ( – ''Makhteshim'') is a

geological Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Eart ...

landform considered typical for the

Negev The Negev or Negeb (; he, הַנֶּגֶב, hanNegév; ar, ٱلنَّقَب, an-Naqab) is a desert and semidesert region of southern Israel. The region's largest city and administrative capital is Beersheba (pop. ), in the north. At its southe ...

desert of

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

and the Sinai peninsula of Egypt. A makhtesh has steep walls of resistant rock surrounding a deep closed valley, which is usually drained by a single

wadi Wadi ( ar, وَادِي, wādī), alternatively ''wād'' ( ar, وَاد), North African Arabic Oued, is the Arabic term traditionally referring to a valley. In some instances, it may refer to a wet ( ephemeral) riverbed that contains water on ...

. The valleys have limited vegetation and soil, containing a variety of different colored rocks and diverse

fauna and flora In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

. The best known and largest makhtesh is

Makhtesh Ramon Makhtesh Ramon ( he, מכתש רמון; ''lit.'' Ramon Crater/Makhtesh ; ar, وادي الرمان, links=no) is a geological feature of Israel's Negev desert. Located some 85 km south of the city of Beersheba, the landform is the world' ...

Etymology

Although commonly referred to as "craters", these formations are "erosion cirques" (

steephead valley A steephead valley, steephead or blind valley is a deep, narrow, flat bottomed valley with an abrupt ending. Such closed valleys may arise in limestone or karst landscapes, where a layer of permeable rock lies above an impermeable substract such ...

s or box canyons). Craters are formed by the impact of a meteor or

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...

eruption, whereas makhteshim are created by

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is di ...

. The word makhtesh is the Hebrew word for a mortar grinder (). The geological landform was given this name because of its similarity to a grinding bowl.

Geology

Where a hard outer layer of rock covers softer rocks, erosion removes the softer minerals relatively quickly, and they are washed away from under the harder rock. The harder rocks eventually collapse under their own weight, and a crater-like valley structure is formed. In Negev and Sinai makhteshes, the hard rocks are limestone and dolomites, while the inner softer rocks are chalk or sandstone. The center of the Negev is dominated by northeast-southwest anticlinal ridges. The crests of four ridges host five deep valleys surrounded by steep walls. The upper half consists of hard limestone and dolomite, and the bottom of friable sandstone. Each valley, known as a makhtesh, is drained by a narrow river bed.Makhteshim Country

Negev

The Negev has five makhteshes: Makhtesh Ramon, Makhtesh Gadol, Makhtesh Katan, and two small makhteshes on

Mount Arif Negev Mountains is a mountainous area in the north-western part of the Negev desert, in Israel. Mount Ramon is the summit of Negev Mountains and the highest point in southern Israel, reaching . Most of the area belongs to Negev Mountains Nature ...

, south of Makhtesh Ramon. *

is exceptional as it is drained by two rivers (Nahal Ramon and Nahal Ardon). It is the largest makhtesh at over 40 km long, 2–10 km wide and over 500 m deep. The rocks in this makhtesh contain thousands of

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttle ...

fossils, as well as volcanic and

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, cau ...

rocks. * Makhtesh Gadol (''Large Makhtesh''). At the time of naming, Makhtesh Ramon was uncharted, and so this was thought to be the largest makhtesh, at 10 km by 5 km. * Makhtesh Katan (''Small Makhtesh'') is the smallest major makhtesh at 7 km by 5 km and was charted in 1942 by Jewish explorers.

Sinai

The two makhteshes in Sinai, Egypt, have no names for the basin, but their walls have several names including ''Jabal al-Manzur'' or ''Gebel Maghara''.

Jordan

Many similar geological formations are also found in Wadi Rum in southern Jordan.

Gallery

File:SmallCrater01 ST 08.JPG, The walls of the Makhtesh (small Makhtesh) File:SmallCrater05 ST 08.JPG, Colorful sandstone in Makhtesh Katan Image:SmallCrater03 ST 08.JPG, Makhtesh Katan Image:SmallCrater06 ST 08.JPG, Colorful sandstone in the small Makhtesh Image:MakhteshGadolAcacia.jpg, Acacia tree inside Makhtesh Gadol Image:MakhteshGadolMist.jpg, Mist flowing over the northern rim of Makhtesh Gadol Image:RamonFault.jpg, Ramon Monocline on the southern side of Makhtesh Ramon Image:RamonFault1.JPG, Ramon Fault on the southern side of Makhtesh Ramon