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6 - Varves

by Jefferson Williams

Varves are annual layers of deposition in the sediments. If we can identify varves in an outcrop or a core we can count years of deposition just like we can count years of growth from tree rings. A varve typically consists of one light and one dark layer of sediment. The light and dark layers are deposited during different times of the year. Thus, one pair of light and dark layers constitutes one year of time and by counting these couplets (i.e. varves), we can count years of deposition. Varves are present in salty (aka evaporitic) lakes such as the Dead Sea. Unfortunately, the varves of the Dead Sea are not always well defined. Many of the Dead Sea varves are ambiguous. This means one can’t (for now) determine the exact year when this seismite was formed. At best, one can only define a time span of several years when the earthquake occurred.

To the right is a thin section (i.e microscope slide) created from a core taken near En Gedi in 1997. It shows several years of varve couplets with one well defined varve couplet surrounded by a white rectangle. The whitish layer at the bottom of the rectangle is almost pure aragonite; a type of Calcite (CaCO3) that may precipitate out of the Dead Sea in the Spring. The darker top layer is flood deposit(s). In the winter and spring, a few rain storms cause the normally dry steams of En Gedi to flow and as they flow, they bring sediments which are deposited at the sea floor.

Using thin section slides from En Gedi, I counted varves from the top of the 31 BC Josephus Quake to the top of the Jerusalem Quake. I also estimated the accuracy of my date for the Jerusalem Quake. I concluded that the Jerusalem Quake struck between 26 and 36 AD; the years when Pontius Pilate was procurator of Judea and when the earthquake of the Gospel of Matthew is historically constrained. My best guess is that the earthquake in the sediments likely occurred sometime between 29 and 33 AD. Along with some German colleagues, I published this research in 2012.

So, the earthquake in the sediments appears to have occurred more or less during the same time period when Jesus of Nazareth died but we still don’t know if the earthquake in the sediments is the same earthquake reported in Matthew. In fact, we still don’t know if Matthew’s earthquake is an accurate report of an actual geologic event. The description in Matthew could be pure allegory. This leads to the current focus of my research; finding temporal patterns in the sediments.

While the biblical accounts are vague about the year of the crucifixion, they are specific about the time of year that the crucifixion occurred; on the 14th or 15th day of the Jewish month of Nisan. If there is a way to determine what time of year the sediments immediately on top of this earthquake were deposited, we could determine if this was a spring, winter or fall earthquake. And there are other events reported to have occurred on the day of the crucifixion that could have left a record in the sediments.

References Video(s)
Video(s) of flash flood deposition

  • Left is a Flash flood in En Gedi (Winter 2009)
  • Note the plume of muddy water going out to sea. As the sediments in that muddy plume drop to the bottom of the Dead Sea, they leave a thin flood deposit.

  • Right is a Flash flood in Elat (Winter 2013)
  • This video shows the plume from the surface and the resulting hyperpycnal flow under water