HaMakhtesh HaGadol

HaMakhtesh HaGadol lies east of Yeruham in the Negev highlands.[3] The Encyclopaedia Judaica geographical survey places it in the Northern Negev Highlands, a short distance north of the Valley of the Zin River, while another Encyclopedia.com entry lists it among the central Negev Hills.[5][6] These differing regional descriptions have both been retained rather than treating either as definitive.

Published dimensions vary. A 2007 Ynet account describes an elliptical basin about 14 kilometers long and 5 kilometers wide.[2] A Mako travel article gives a length of 14 kilometers, a width of 6 kilometers, and a maximum depth of 410 meters, while another Mako article gives approximately 10 by 5 kilometers and a depth of up to 250 meters.[3][1] The Ynet account describes the makhtesh as enclosed except for a single breach through which its stream drains.[2]

Mount Avnun, also spelled Avnon, rises to 656 meters above sea level on the western rim and serves as the principal overlook for visitors approaching from Yeruham.[3] The Small Fin and Large Fin are prominent hiking features near the eastern side, and the Colored Sands parking and recreation area lies within the makhtesh.[3] The same source identifies Har HaKarboleth as the eastern boundary and Mount Hatira as the western boundary.[3]

HaMakhtesh HaGadol is an erosional basin rather than a meteorite-impact crater. It developed as erosion transformed an upward-folded rock structure, or anticline, into a deep valley-basin.[5] A Ynet account reports that geological theories place its age at a minimum of roughly 15 million years.[2] Erosion exposed sedimentary strata on the floor that are older than the rocks forming the enclosing walls.[5]

The steep walls consist of Nubian Sandstone overlain by more resistant limestones and dolomites.[5] Unlike Makhtesh Ramon, HaMakhtesh HaGadol and HaMakhtesh HaKatan were not substantially shaped by faulting, according to the Encyclopaedia Judaica survey. Marine Jurassic deposits are recorded in the anticlinal core, while Lower Cretaceous Nubian Sandstone appears in the makhtesh as an erosion window.[5]

The Geological Survey of Israel documented exposures of the Hatira Formation at numerous surveyed quarry sites. These included white, yellowish, reddish, and varied sands; ferruginous horizons and crusts; kaolinitic clay; silt and clay interbeds; and cross-bedded strata.[7] These observations describe particular survey sites rather than a single uniform section across the entire makhtesh. Elsewhere on the floor, fossil forests, coral reefs, shell and clam fields, and colorful mineral deposits record earlier terrestrial and marine environments.[2]

Nahal Hatira is the principal drainage stream. It runs parallel to the long axis of the makhtesh, breaches the eastern wall in a gorge, and continues toward the Zin River.[5] Near the eastern outlet, Ein Yorke'am is a seasonal spring and deep pool replenished by flash floods from Nahal Hatira; its water can remain for months after a flood.[3]

International recognition of the Negev makhteshim helped establish the Hebrew term makhtesh as a general geological term for this class of erosional crater.[4]

In spring 1942, a five-man expedition set out to survey desert routes and water sources on behalf of the Haganah, carrying 15 Palestine pounds supplied by Haganah leader Yisrael Galili.[8] The team sought to assess the terrain's suitability for Palmach training and prepare an initial map of paths, wadis, and water sources. Its members were Ezra Kaduri, Menshke (Babayoff) Harel, Moshe'le Horowitz, Ahuvia Malkin, and Aryeh Ben-Gurion.[8]

The group reached what is now called HaMakhtesh HaGadol during a survey between Ein Gedi and Sodom. According to its later account, the members arrived at night, climbed upward, and named the formation "the makhtesh," with "the Big" added later to distinguish it from the neighboring Small Makhtesh.[8] Harel recalled their astonishment at the colorful sandstone. The expedition members believed that no Western researcher had previously written about the site, but their account presented that conclusion as probable rather than certain.[8]

After two weeks in the field, their rough survey became the basis for a more detailed map at a scale of 1:100,000, completed after their return to central Palestine.[8] During the 1940s, British authorities regarded the makhtesh as a mineral resource, built roads across it, conducted oil drilling, and restricted access using military forces and Bedouin scouts. Entering the restricted area consequently became a test for Palmach reconnaissance units, and the makhtesh later became a destination for youth-movement hikes during the 1950s.[2]

A 1994 government decision designated the Negev crater region a national geological park, citing the nationally and internationally significant natural values of Makhtesh Ramon, HaMakhtesh HaGadol, the Small Makhtesh, and the two Arif makhteshim.[9] A 2007 Ynet account also reported that HaMakhtesh HaGadol had become a declared nature reserve, although it did not give the date of the declaration.[2]

The Geological Survey of Israel documented quarry and mining sites in HaMakhtesh HaGadol in Report GSI/35/95, dated March 1996 and prepared for the Quarry Rehabilitation Fund.[7] The report assessed the sites' locations, geological settings, extracted materials, remaining reserves, and rehabilitation requirements.[7]

Sandstones of the Hatira Formation were mined for industrial sand, including material suitable for glass production. At a quarry about 1,200 meters north of the Colored Sands parking area, surveyors recorded a 25–30-meter section containing varied sands, clay and silt layers, and ferruginous crusts, with beds dipping about 20 degrees eastward. The report estimated at least tens of thousands of tonnes of glass-quality industrial sand, with potentially larger quantities north of the site.[7] At Yotam Quarry on the southern bank of Nahal Hatira, it recorded a roughly 70-dunam working area, sand-processing equipment, access roads, and a quarry wall exposing 5–7 meters of white sand. Estimated remaining reserves in the stripped area were approximately 100,000 tonnes, with potentially several times more in the surrounding zone.[7]

For sites with reserve estimates, the survey cautioned that more accurate figures required subsurface information about the quantity and quality of the material.[7] Rehabilitation proposals included flattening waste piles, closing excavations where mining would not continue, and preserving quarry walls displaying geologically or aesthetically significant features. Examples included a small canyon and seasonal rainwater pond that had developed in an excavation and a colorful patina on a clay exposure.[7] The visibility of disturbed sites from Mount Avnun and other viewpoints was also considered when setting rehabilitation priorities.[7]

The makhtesh contains several natural features that attract hikers and other visitors. Its mineral deposits produce multicolored sands, and a designated parking and recreation area allows visitors to view the sands near the center of the basin.[2][3] Expedition member Menshke Harel later recalled the striking variety: "Here you take an axe, strike the sandstone wall, and with every blow sand of a different color pours out."[8]

The floor contains petrified tree remains associated with a fossil forest, along with exposed ancient coral reefs and accumulations of shells and clams.[2] Ein Yorke'am, near the eastern outlet, consists of a seasonal spring and a deep pool replenished by flash floods from Nahal Hatira.[3] The spring also forms an important ecological niche for ibex and other desert animals, making protection of the water and its surroundings especially important.[10]

Mount Avnun on the western rim, at 656 meters above sea level, provides an accessible panoramic view over the basin.[3] The Small Fin offers a short but steep family hiking route, while a longer continuation reaches the Large Fin and requires different transport arrangements for the return journey.[3]

The formation is known by several names. Makhtesh Hatira, derived from the ridge and stream associated with the basin, appears in geographical and older travel accounts.[5][2] Modern travel articles also use Makhtesh Yeruham, after the nearby town; one Mako article calls it the formation's updated name, while a Maariv article describes that renewed name as somewhat confusing.[1][10]

A 2007 Ynet account states that Hatira was used for a period and that the authorities later restored the original popular name, HaMakhtesh HaGadol.[2] Consequently, HaMakhtesh HaGadol, Makhtesh Hatira, and Makhtesh Yeruham all continue to appear across published accounts.[1][2]