4 March 2022 Photos by the author except as indicated.
Both one evening in March, alone, and the following morning with Yonatan, I visited the Makhtesh HaGadol, which is also known as the Makhtesh Khatira. Makhteshim (the plural of makhtesh) are also known colloquially as craters, but only due to their superficial appearance, since they are not true craters, which are formed by the impact of a meteor or volcanic eruption. In fact a makhtesh is a geological landform only found in the Negev desert and the Sinai Peninsula (with perhaps a small number of minor examples in Jordan. Created by water erosion, makhteshim have steep walls of resistant rock surrounding a deep closed valley, which is usually drained by a single wadi. The valleys have limited vegetation and soil, containing a variety of different collared rocks and diverse fauna and flora.
The process of formation of a makhtesh occurs where a hard outer layer of rock covers softer rocks, and erosion by water removes the softer minerals relatively quickly, washing them away from under the harder rock, which eventually collapses under its own weight, to reveal a crater-like valley structure. The Hebrew term, makhtesh (מַכְתֵּשׁ)―which is used by geologists worldwide―is also the word for a mortar, as in pestle and mortar. It is thus very descriptive of these bowl-shaped landforms, which can also be called erosion cirques, steephead valleys, or box canyons.
One of five makhteshim in Israel―there are two more in Sinai―HaMakhtesh HaGadol is the second largest, despite its name meaning 'the large makhtesh' (!); it was discovered and named before Makhtesh Ramon, which is actually the largest makhtesh in the world, was charted. Some ten by five kilometres, it is drained by Nahal Hatira. The location for the development town of Yeruham, on its western edge, was chosen because the region―and especially the makhtesh―was thought to be rich in natural resources.
So a narrow road―route 225―heads east out of Yeruham, where we were staying, and snakesgoes down into the makhtesh, traversing it to its eastern side and coming out at Yorqueam; it is the only paved road in the makhtesh. But before the western descent, there is a gravel ascent up mount Avnun, where their is a viewing platform just below the summit. As sunset approached I made my way there in the car, somewhat gingerly, stopping halfway up to inspect some not-so-ancient ruins. These are the remains of the Mount Avnun Oil Exploration Camp established by the Iraq Petroleum Company (IPC) in 1941.
The IPC―known prior to 1929 as the Turkish Petroleum Company―is now jointly owned by some of the world's largest oil companies, and headquartered in London, although today it is only a paper entity with historical rights, and plays no part in the modern development of Middle Eastern oil. But in the 1930s it was active in the search and exploitation of oil resources in the Middle East and nursed aspirations to expand into mandatory Palestine. In 1938, the Mandatory government promulgated a suitable ordinance and the next year issued thirty-one licenses, eleven of which were taken by the IPC. Following this, a subsidiary, the Petroleum Development (Palestine) Ltd, conducted geological surveys in the 1930s and 1940s, believing that there was a good chance of oil trapped above the groundwater in the Makhtesh Hagadol. In 1941 they paved a metalled road, the Oil Road―from Negev junction on what is now route 40, at Be'er Sheva, east through what is now Yeruham, and into the crater (now route 225), continuing east (on what is now route 227) to Ma'ale Akrabbim (the Scorpions' Ascent), which had been paved in 1927. The Oil Road remained, prior to 1956, the primary route from Be'er Sheva to Eilat. Having prepared suitable access roads, the company then drilled in the base of the crater, believing that this would be closer to the oil deposits. Today all that remains of the drillings is a dirt road paved with fieldstones by the British during World War II, leading off route 225, in the base of the crater, to the abandoned drilling site some 2.5 kilometres to the south, where engineers cast a concrete surface on which the drilling tower was to stand.
Outside the crater, on the ascent of Mount Avnun, the IPC built a residential camp for road and drilling workers, with stone buildings either side of the ascent track. A residence, a dining room and service buildings remain, albeit in ruins following their demolition, to prevent squatting by Bedouin apparently.
Buildings of the northern (left) and southern (centre) camps, and a concrete platform over a filled-in pit (right); could this be for a drilling dry run, since the actual drilling was done inside the makhtesh and not at the camp?
The British drilling plans did not materialize due to the deteriorating security situation and the outbreak of the War of Independence in 1948, and they abandoned the site. With the establishment of the state of Israel, oil companies renewed their attempts to find oil in the crater, but in the end found none and the drilling was abandoned. Only the ruins of the workers' camp and the concrete surface for the drilling tower, at the bottom of the makhtesh, still remain.
The next day Yonatan and I entered the makhtesh, stopping at the head of the British road leading from route 225 to the drilling site, because just here near the main road are the remains of several huge fossilized tree trunks. Or are they?
They certainly look like the remains of huge tree trunks, lying on the sand, about a metre in diameter and several metres long, in broken sections, on a sandstone slope. There are more examples scattered at other sites in the makhtesh―including next to the Khatira quarry to the north―but these are largest ones. The site is certainly of great scientific importance. Almost everywhere you look for information―whether on maps, in leaflets, or on the internet―you will read that these are petrified trees. But the first clue they might not be is the brown tourist sign pointing them out to the passing traveller. In the past, this sign was marked ‘fossil trees’, but in recent years it was changed to ‘quartzite sandstone’ (אבן חול קווארצית), in recognition of the fact that another explanation is that these are not trees at all.
First a little about why they might be trees. During the Jurassic period, which began 200 million years ago, long before humans, there was rainy weather in the Negev, similar to a modern equatorial climate, and impressive forests covered the area of today’s Negev desert. When a tree collapsed, its fate was one of two, based on local conditions: in an environment rich in oxygen, the tree would rot and disappear. But in an environment of sandstone and clay with swampy terrain, a tree falling into the swamp would be quickly wrapped in sediment, leaving an oxygen-free environment so that the wood could not rot. Gradually sediments wild replace the organic matter, taking on the shape and texture of the wood, often in fine detail including tree rings, insects in the wood, and so forth. Hence the identification of these tree-like artifacts as fossilized trees.
But although these geological artifacts have long been identified as fossilized tree trunks, the geologist Yoav Avni, a researcher at Geological Survey of Israel, has claimed that they do not have any sign of wood-like internal structure, or any other signs of having been trees beyond their superficial shape and colour. Rather, he argues, they are the result of ferrous solutions that hardened the quartzite sandstone until they resembled tree trunks, similar to the formations at the ‘Forest of Pillars’―a mound of naturally occurring tube-shaped rocks―at the foot of Gebel Et Tih in the central Sinai. Either way, they are very impressive.
We continued to the eastern side of the makhtesh to see a particularly fine collection of coloured sands for which the makhteshim are famous, gathered in one spot near the Holot Tziv'oniyim ('colourful sands') campground. The coloured sands result from the erosion of hills in the makhtesh, created hundreds of millions of years ago by ancient rivers that deposited their quartz- and feldspar-laden silt, which have subsequently been eroded. The type and concentration of oxides in the sand determines the colour: green, orange, purple, white, red, yellow, white, or beige.
Today mining, drying and screening of quartz sand is the sole activity carried out in the makhtesh, at its northern end.
Running out of time, we could only look up at HaSnapir Hagadol (the large fin), a sharp ridge along the eastern wall of the makhtesh, which is walkable, as we left the makhtesh.
Crossing the eastern entrance to the makhtesh is a railway bridge, carrying a freight line which runs between the Zin and Oren phosphate plants and the mainline at Dimona, running north-south along the eastern edge of the makhtesh.
Having passed under it, we reached Yorkeam junction where we turned around and retraced our steps to Yeruham.