Iron Age copper mining caused large-scale environmental collapse
For thousands of years the minerally rich Timna mines, in southern Israel, produces massive quantities of copper ore. Yet, in the early Iron Age, the ever-growing need for material to fuel the smelters led to an ecological collapse whose effects are still visible today. According to an article published in the journal Nature, the excessive use of the white broom bush and the ecological keystone acacia tree was so significant as to destabilize the local ecosystem and bring mining operations in the area to a sudden halt.
A Climatic Disaster in Biblical Times
Nicknamed King Solomon’s Mines, Timna is located in the Arava Valley, 12 miles north of the Gulf of Aqaba and within the most arid region of the entire Negev Desert. Utilized since the Chalcolithic period (c. 4500-3300 BCE), the Timna mines were one of the most important sources of copper in antiquity. Yet in the ninth century BCE, mining at Timna came to a sudden halt, not to be restarted for nearly a thousand years.
Although earlier theories as to the halt of copper production focused mainly on outside external factors, such as the ninth-century campaign of Hazael into Canaan, a new study by a Tel Aviv University team posits a different idea—that the over-exploitation of the already poor Timna ecosystem led to extreme environmental degradation, which in turn made continued mining financially unviable. The ecological effects of this event can still be seen in the area around Timna, where acacia trees and other desert flora are all but absent.
Timna saw a dramatic increase in copper production from the 13th through ninth centuries due to new mining and smelting techniques and a greater level of organization. Controlled by Egypt for the early stages of this development, Timna became a key economic component of the early Edomite kingdom following the Bronze Age collapse and Egypt’s withdrawal from the southern Levant. The Timna mines reached their zenith around the tenth century BCE, the period of the biblical kingdom of David and Solomon in the Judean Highlands. Only a century later, however, this production entirely disappeared.
Analyzing Slag to Reveal an Ecological Disaster
To better understand the sudden halt in production, the Tel Aviv team examined two large slag and industrial waste heaps at Timna, especially used charcoal. Over the years, spent charcoal was routinely placed on the same pile, leaving a stratified sequence that can be studied much like an archaeological mound. Through analysis, the team was able to determine the specific types of fuels used in the smelting process.
The team found that for much of the 11th through tenth centuries, the main sources of fuel were acacia trees and white broom bushes. Both of these grow throughout the region, and acacia is frequently mentioned as being used by the Israelites during their 40 years wandering in the desert (Exodus 25:10). However, the most important quality of acacia and white broom is their caloric density, which allows for their coal to burn much hotter. This, in turn, makes them far more efficient for smelting. During the 11th through tenth centuries, acacia and white broom made up nearly 90 percent of the fuel used for smelting the hundreds of tons of copper produced at Timna. Yet this mass-scale smelting would have required far greater quantities of acacia and white broom than the area around Timna was capable of producing.
By the end of the tenth century, the sources of fuel swiftly change to less efficient sources such as date palms. With the nearest oasis capable of growing palms located miles away from Timna, the team suggests that the acacia trees and white broom bushes had been harvested to extinction in the area surrounding the mines, leaving no choice but for the miners to continually go further and further afield just to harvest less and less efficient materials. This did not only affect the financial viability of the mines, however but the very environment.
The acacia tree is a keystone plant within the desert ecosystem of the Negev. Numerous other plants and animals rely on the acacia tree as it provides shade, and food, and traps large quantities of water within the ecosystem that would otherwise be lost. As a result, species diversity within the Negev can be directly linked to the number of acacia trees. Yet, these long-lived trees have infrequent periods of recruitment, making them incredibly vulnerable to overharvesting. Overharvesting was exactly what they experience. “These are very hardy plants, which can survive the extreme temperatures, the salt in the sediment and the droughts,” Mark Cavanagh, one of the researchers, told Haaretz. “But once you add the human element into this equation and you have people industrially removing the vegetation for smelting fuel, cooking, building tents, and feeding animals, you are upsetting a system that is already fragile.”
Calculating the amount of copper produced, the amount of fuel needed, and the percentages of each plant used for fuel, the team estimated that from the eleventh through ninth centuries, the Timna mines could have used nearly ten thousand acacia trees and hundreds of thousands of white broom bushed. With the acacia trees and white broom bushes of Timna, all but annihilated, the ecosystem collapsed, and biological diversity in the area plummeted. The sudden lack of adequate amounts of fuel in the area rendered the Timna mines financially unviable.
Worse yet, the effects of that environmental disaster were so detrimental to the region, that even today they can still be noticed in the area surrounding the mines where biological diversity remains noticeably lower than in other areas of the Arava Valley.
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