Thegeology of Israel includes igneous and metamorphic crystalline basement rocks from thePrecambrian overlain by a lengthy sequence of sedimentary rocks extending up to thePleistocene and overlain with alluvium, sand dunes and playa deposits.[1]
Israel is underlain byigneous andmetamorphic crystallinebasement rocks of the ArabianCraton formed during thePrecambrian, although in places these rocks remain poorly studied. Precambrian rocks are only exposed in southern parts of the country, such asamphibolite atMakhtesh Gadol. Other Precambrian units include the TabaGneiss, Roded and Elatschist, gneiss andmigmatite,syenite, DuhaylaGranodiorite, Darba Tonalite, Abu Saq'a Schist, Abu BarqaMetasedimens, SaramujConglomerate, Sammaniya Microgranite, YutumGranite, QuaniDiorite, Elat Conglomerate,rhyolite,gabbro and other basic rocks.[2]
Mantle-derivedbasalt magma ascended through rocks in theTimna Valley in southern Israel, providing the heat to form alkali granite, alkali rhyolitedikes and layered serptinized gabbro in the core of Har Timna.[3]
The Burj DolomiteShale formation (which includessandstone,dolomite, andmudstone) and the Umm Ishrin Sandstone formation both date to theCambrian and appear in the stratigraphic record of central Israel. The region has little evidence of mid-Paleozoic rocks; sandstone,limestone,clay, andgypsum represent most of the sequence from thePermian andTriassic.
Southern Israel hasOrdovician age rocks in the Disi Sandstone Formation. Other Paleozoic rock units such as the Yam Suf Group (sandstone, conglomerate, mudstone, dolomite and limestone, Amudei Shelomo and Timna formations), and Shehoret and Netafim formations (all from the Cambrian) appear only in the south.[4]
Limestone up to 193 meters thick marks the UpperJurassic in central Israel, followed by the basalt Tayasirvolcanic rocks; the 120 meter Kurnub Group (sandstone, limestone and clay); and 670 meters thick Nabi Sa'id, Ein el Esad, Hidra, Rama and Kefira formation (marl,chalk, sandstone and limestone) from the earlyCretaceous. Basalt andbasanite are both exposed from the Cretaceous in the north.
Limestone, dolomite, chalk and marl formed duringTuronian andSantonian times, chalk andchert during theCampanian. The Mishash Formation of the same age contains similar rocks, 86 meters thick, as well asphosphorite. The Hatrurim Formation, or "Mottled Zone," encompasses metamorphosedMaastrichtian throughMiocene rocks. In places the Mesozoic was a time of microgabbro anddiabase intrusion.[5]
Chalk, marl and clay of the Mount Scopus Group formed from theSenonian into thePaleocene. During thePaleogene, deposits up to 150 meters thick comprised the Adulam Formation (chert and chalk); 350 meters of limestone of the Timrat, Meroz, and Yizre'el formations; 100 meters of Maresha Formation (chalk); and the similar Avedat Group and Bet Guvrin Formation—all in theEocene.
The 40 meter thick Lakhish Formation (limestone); 230 meter thick Hordos and Umm Sabun formations (sandstone, mudstone, siltstone, and conglomerate); and the 50 meter thick Ziqlaq Formation (limestone) deposited in theMiocene. Intermediate basalt erupted during the same time period.Pliocene rocks include 30 meters of marl in the Yafo Formation and marl, conglomerate and sandstone 20 meters thick in the Bira, Gesher and Pleshet formations.
Conglomerate and volcanic rocks mark the transition to theQuaternary. During the last 2.5 million years, sandstone, mudstone,oolitic limestone, conglomerate, gypsum, andaragonitevarves were deposited as well astravertine, calcareous sandstone, red sandyloam, andalluvium. Recent sands and alluvium dominates most river valleys and coastal areas, while conglomerate,gravel andplaya deposits are more common in the south. Basalt and basanite continued to erupt in the north.[5]
Salt is an essential commodity and has been used in the past as an important currency.Mount Sodom was used for salt mining in prehistoric times, and archeological excavations uncovered installations for the loading of salt from theRoman period. In the modern era, salt production plants were built inAtlit,Eilat and along theDead Sea. The salt is produced by the process ofsolar evaporation in ponds andseawater desalination.
A high concentration ofmagnesium with high purity made Israel one of the most important sources of its production. Potassium chloride (potash) is a rich fertilizer for agricultural crops and is produced south of the Dead Sea. During the production process,bromine-rich solutions (used in medicine, industry and cosmetics) remains in the evaporation pools, but its production ceased after it was discovered that this substance emitsozone into the atmosphere.
Phosphate deposits have been discovered since 1950 in several areas in the south of the country, mainly in the craters in theNegev and nearArad. Copper is mined from shafts in the Timna Valley.Manganese ore was also found in the Timna Valley but not in economical quantities. There are a few concentrations ofiron ore inGalilee, in theBeit Netofa Valley, at the foot ofMount Tabor, and several sites in the Negev, but these remain unexploited.
