Glycymeris
Dear Friends,
When I arrived in Haifa, I went walking along the beach. The beaches here are composed of very yellow sand with lots of shells scattered through it (wonderfully, it is really sand, not the rock studded gravel we claim is sand in the Northwest). While on the beach, I picked up three shells because I thought they looked vaguely related to scallop shells and scallop shells are the symbol of pilgrims and I was reflecting about how I’m in the Holy Land and, thus, on an odd, study-filled pilgrimage. Also, what else do you do with pretty shells other than pick them up?
One of the classes I’m taking is “General and Coastal Geoarchaeology.” Geoarchaeology is basically archaeology for geology nerds or geology for archaeology nerds, you focus on studying really ancient peoples through the geological context. Anyway, we’ve been learning about the geology here in Israel. This includes really young rock ridges called kurkar; young meaning 65,000 years old. For comparison’s sake, the Mediterranean is about 20 million years old and is left over from the Tethys Sea which was around 200 million years ago.
We don’t know how old the sand is here, but it comes from the Nile River. Way down at the source of the Nile are granite rocks. Granite is composed of four minerals: mica, feldspar, plagioclase and quartz which the Nile erodes these as it passes through. The first three are rather soft minerals, so they erode away as the Nile flows down towards Lower Egypt (to use the ancient name). By the time the Nile reaches the Delta, only the quartz is left because it is one of the hardest minerals after diamonds. From the Delta, it is picked up by longshore currents which move counter clockwise around the Mediterranean. Eventually, the sand reaches Israel, decides it has had enough, and does not continue north of Haifa.
At some point along the way, the Sea brings up these shells and leaves them everywhere in the sand. Incidentally, they’re not scallop shells they’re glycymeris shells. Glycymeris are saltwater clams and they’re one of those things that have been around forever. Some scientists decided to carbon date these shells and figure out how old they are. Friends, the shells I picked up from the beach are five thousand years old. … Babies, geologically speaking.
Hope all is going well for you all!
Pax!
DS
