Religious Jews and others believe it was God who instructed King David to make Jerusalem his capital, but now a US geologist claims that the limestone landforms near the Gihon spring is what decided it.

An excavation site in the City of David.
Photo: Courtesy of the Shalem Center

Dr. Michael Bramnik of Northern Illinois University lectured on the topic at last week's annual meeting of the Geological Society of America held in Portland, Oregon.

Having conducting a "new analysis of historical documents and detailed geological maps," Bramnik said in a speech on "Bedrock of a Holy City: The Historical Importance of Jerusalem's Geology" that the city's geology was crucial in transforming it into the religiously important city that it is and the foundation stone of Judaism.

In 1,000 BCE, the Jebusite city's water system proved to be its undoing, said the researcher. "The spring of Gihon sat just outside the city walls, a vital resource in the otherwise parched region. But King David, intent on taking the city, sent an elite group of his soldiers into a karst limestone tunnel that fed the spring. His men climbed up through a cave system hollowed out by flowing water, infiltrated beneath the city walls and attacked from the inside. David made the city the capital of his new kingdom, and Israel was born."

Karst landforms are characterized by weathering caused by the breakdown of soluble bedrock due to physical, chemical or biological processes.

Limestone areas are weathered when rainwater, which contains a weak carbonic acid, reacts with limestone, causing the mineral to be eroded. The resulting pattern is called karst scenery. Rock openings expand, and an underground drainage system begins to develop, allowing more water to pass through the area and accelerating the formation of underground karst features.

King Hezekiah, one of David's successors, watched as the Assyrians, a group of warriors stronger than the Jews, toppled city after city in the region. Fearing that they'd soon come for Jerusalem, he also took advantage of the limestone bedrock and dug a 550-meter-long tunnel that rerouted the spring's water inside the city's fortified walls and can still be seen and visited today.

The Assyrians laid siege to the city in 701 BCE but failed to conquer it. Jerusalem was the only city in history to successfully fend them off, said the geologist.

"Surviving the Assyrian siege put it into the people's minds that it was because of their faith that they survived," Bramnik said. "So when they were captured by the Babylonians in 587 BCE, they felt it was because their faith had faltered. That conviction united the Jews through the Babylonian captivity, and so began modern congregational religion."

In an arid region rife with conflict, water security is as important today as it was during biblical times, Bramnik concluded. "I think Jerusalem's geology and the geology of Israel are still significant to life in the region, perhaps even reaching into the political arena."