Friday 3 April 2015

Jesus’ Easter: a geological tour

Limestone is not common in the Northern Rivers but there are several
small locations where it does occur (This picture is from near Tabulam).
Since this is the first day of Easter where Christians remember the death and resurrection of Jesus at Jerusalem, I thought I’d give some background by way of the geology of the city. Like all landscapes the landform that makes up the hills and valleys around the Holy City can be seen in the geology.

At the festival of Passover Jesus entered the city of Jerusalem from the western side from Bethany. Passing into the Kidron Valley and then up to the city. At Bethany the rock types are dominated by Cretaceous aged chert and chalk of the Mishash formation of the Mount Scopus Group. These rocks are typically marine deposited sediments made from the build-up of microscopic creatures called diatoms. Descending into the Kidron Valley the chert which caps the hills to the east of the city gives way to chalk and claystone which is much more erodible. This chalk and claystone is the Menusha Formation which is the earliest formation in the Mount Scopus Group.

Stratigraphy of the Jerusalem area
Image courtesy of  Dov Frimerman
Ascending into Jerusalem the geology changes to limestone of the Nezer and Shivta formations of the Judea Group. The limestones of the Judea Group dip at an angle of around 10-15 degrees. This means that any ground water travelling though the limestone flows to the west to the sacred springs along the top of the Kidron valley. The garden of Gethsemane where Jesus spent his last night praying is in the area of these springs.

The limestone is the rock that underlies all of the places where Jesus spent his last days. Jesus drove people from the Temple claiming that they were stopping people from reaching God. The foundations of the Temple are built on this limestone. Jesus was placed on trials for treason at the Roman governor Pontius Pilate’s palace and also at King Herod’s Palace around Mount Zion. Again, these places were built on the same Limestone.

The exact place of Jesus’ execution and burial is the subject of some debate. There appears to be a couple of alternative sites but all of which are in areas were limestone is dominant. This is particularly evident with the description of Jesus being crucified ‘near’ the city and the description of Jesus being buried in a cave. The old city of Jerusalem was built entirely on the Judea Group and limestone landscapes are very well known for having many cave systems. Caves are well known in the area around Jerusalem.

In the Northern Rivers of New South Wales there is a mountain called Mt Jerusalem which is part of the world heritage system of National Parks around the Tweed Valley. But the geology of Mount Jerusalem, NSW is a post for another day.

Want to see more? Here is the Israeli geological survey’s 1:25 000 scale maps of the country or here is a good website describing the geology of Israel in more detail. To find out more about Jesus during his last days the accounts of his apostles in the Bible is the most detailed description that remains. There are other references from other sources such as Josephus and Tacitus but nothing as comprehensive as the accounts of Matthew, Mark, Luke and John in the Bible.