Building With Basalt
With its eery, massive buildings of dark, local basalt rising from the surrounding desert plain, Umm el-Jimal's architecture is perhaps its most visually arresting feature. But basalt shaped more than the site's vertical appeal. The black volcanic stone—today often mottled in appearance from lichen, dust, and age—was so sturdy that many homes were built to three stories tall, with the tower of the so-called Barracks (or later castellum) six stories above the ground. The results lasted a long time: Not only were buildings maintained and reused over centuries of continuous occupation, but many were reoccupied in the early 20th century and over 150 are still at least partially standing today.
Of Corbelling and Cantilevers
Yet basalt's dense strength came with limits. For one thing, its weight required builders to limit the blocks' length to keep them from cracking in two. As a result, by necessity rooms were usually narrow enough to span with basalt, or contained interior arches to support more ceiling weight and thus allow a wider floor plan. In addition to arches, Umm el-Jimal's builders extensively used a technique called corbelling, whereby basalt blocks (called 'corbels' by architects) projected out from the walls into which they were set in order to bear the weight of the building's ceiling or additional floors beyond ground level. Similarly, the town's ancient residents used cantilevered blocks to form stairways and narrow platforms.
A Frontier Architecture
The basalt's insulating properties helped keep Umm el-Jimal's homes cool in the hot Hauran summer, and kept warmth of fires from escaping during cool winter nights. In many cases, residents used ground-level rooms for their animals, with basalt mangers built right into the walls. The results of this pragmatic style are at once functional and beautiful, and form a unique regional style of ancient architecture found at numerous sites in what is now Jordan and Syria. Check out the slideshows above for more details about the stone and the local construction techniques which made life possible at Umm el-Jimal.
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