Two recent events (geologically speaking)

Rachel Berkowitz

Scientific press conferences don’t often refer to Biblical quotations, but at the American Geophysical Union fall meeting , Zvi Ben-Avraham, head of the Minerva Dead Sea Research Center at Tel Aviv University in Israel, cited Joshua 3:16 in his presentation about sediment cores from the Dead Sea.

Although no one has yet offered an scientific explanation for the Sun standing still during the battle of Jericho, scientists can now explain another phenomenon described in Joshua 3:16, when the “waters which came down from above stood and rose up . . . and those that came down toward the sea of the plain, even the salt sea, failed, and were cut off.”

Ben Avraham pointed out new sediment studies indicating that in 1304 BC, an earthquake of magnitude 6.3 caused a mud slump north of the Dead Sea that cut the influx of the Jordan River for several days.

At 425 meters below sea level, the Dead Sea is the deepest place on Earth’s surface. The drainage basin provides an important record of past climate in the Middle East. The Dead Sea Deep Drilling Project , which began 10 years ago, culminated in the excavation of a 1-kilometer core from the center of the seabed.

White sediment layers deposited over the past 200 000 years indicate summer periods, when lake evaporation leaves calcium carbonate deposits. Dark layers show mud and silt from winter floods and sandstorms. A layer of pure pebbles indicates a completely dried-up sea, which happens during a particularly warm period demonstrates what could happen under the influence of climate change. Earthquake deposits are also found.

Steven Goldstein of Columbia University’s Lamont–Doherty Earth Observatory in Palisades, New York, commented at the press conference that the drilling group had seen for themselves the formation of a dark sediment layer when a flash flood from the side of the mountain entered the lake and carried sediment to the bottom.

Hawaiian volcano

Another AGU press conference again tied other recent geological findings to historical records. Though not a biblical citation, notes from Sheldon Dibble ‘s 1843 diary describe a volcanic explosion in 1790 that led to the loss of many lives. The Kilauea volcano on Hawaii Island, thought to be a gentle volcano with long periods of lava flows punctuated by brief and occasional explosive anomalies, has been dominated by explosive eruptions for 60% of the past 2500 years.

Dibble’s account of the 1790 explosion tells the story of a group of warriors and their families led southward by Keoua on their way to a battle with Kamehameha for control of the island. The travelers waited for three days at the summit, hoping that the explosively erupting volcano would stop. Many were killed as they continued past the summit.

The geological record shows human bodies preserved in the deposits of an explosive eruption, asphyxiated and scorched by hot ash but not burned by lava, clasping each other to keep from being blown away by a hurricane-speed pyroclastic density current.

Research geologist Don Swanson of the US Geological Survey’s Hawaiian Volcano Observatory explained that carbon dating of Kilauea’s lava flows and explosive deposits reveals cycles of activity that have been dominated since 200 BC by either explosive or effusive activity—but never both at once. Now Kilauea is in a calmly effusive stage, but history tells us the calm won’t last forever.

Explosive volcanic events are likely driven by steam. One way that steam-powered explosions can happen is when rising magma heats the groundwater near the water table and leads to an overpressure of steam. The overpressure blows out a rockfall—or crystallized magma—blockage in the conduit, creating a pyroclastic current.

Swanson doesn’t think we can predict when Kilauea will switch from effusive to explosive activity. And whereas examining deposits at similarly behaved volcanoes could reveal patterns regarding explosive–effusive transitions, the depression of the caldera and increased seismic activity will be enough of a warning sign to trigger the evacuation of the volcano area.

Forecasting water levels of the Dead Sea might be more successful, since patterns of climate change are better understood. What’s more, humans are deliberately and somewhat predictably affecting water balance in the region as they divert any available freshwater. With core samples pre-dating ancient civilizations, researchers have at their disposal a new source of information about the effects of climate on human evolution.

Natural events have had an impact on civilization in the past and will continue to do so. Geology, sedimentology, and volcanology: can’t live with ‘em, can’t live without ‘em.