Tuesday, December 28, 2010

Drilling ? Dec 27, 2010

I am running on very little sleep so I will try to sound coherent, but no promises.

Two nights ago I was up for my night duty. It was supposed to be me, dad and another scientist here who lives in Jerusalem, Elisa. The drillers had to start drilling a new hole for a new core, and they were still in the process of getting to the depth that we want to start to recover sediments. So the night sounded like another case where there is nothing for the scientists to really do except keep an eye on the GPS for any extreme movement of the rig. I spent the night before on the rig like that and if it made no difference, I figured I'd rather sleep back at the kibbutz then on that top cot. Dad said he would be staying to matter what, just in case something happened. Elisa decided she may as well stay since she wasn't going to drive back to Jerusalem that night.
Well... let me tell you... I made the right decision in this case! Unfortunately for them the winds picked up over night and there were huge swells. Apparently waves were splashing over the scientist shed. These rough seas kept the boat from coming out to relieve them of duty until 4pm the next day, so they were out there for 24 hours.
I came in on the boat at 4pm yesterday to replace them with another scientist. Unfortunately for the drillers, their night and day shifts are set in stone so if they get stuck out for 24 hours, then the night shift remains on duty and works throughout the night, having to stay for 36 hours. This apparently happened once before when there was a huge storm. It's really unfortunate but fairly unavoidable with the way things are set up.
I felt good because I came bearing gifts from the day shift drillers-- i.e. the three staples that they need to survive: food, coca-cola and cigarettes. Everyone was in pretty good spirits considering being stuck on a small platform in a storm for so long. Dad had a huge smile on his face and was overall in a good mood.
I spent the night shift with Nicolas, an Argentinian who did his degrees in Israel and right now is working as a post doc in Norway. He was pretty entertaining so the night went by pretty well. I also just spent time talking with the drillers. It's nice to be able to chat because it seems like there is a unspoken divide between the scientists and the drillers, even though a lot of us are similar ages (except I guess I'm the youngest person really participating on the project), and similar backgrounds, etc. So I hear from the scientists complaints about how the project is going, how it could be organized better, why they think some things might not be working, then I hear about all those things from the drillers side. It turns out they are mostly all the same ideas, but I get the impression that they are not communicating that to each other very well.
So, yes, so far so good. I spend most of my time wandering around seeing cool landscapes, plants or animals, talking to people, or helping out with some science (although that has been pretty slow recently). It's just good to be more socially open than I was when I was younger. It makes these experience so much better.

Finally I'll give my little daily geology lesson: something new I learned yesterday about sink holes around the Dead Sea.
So the Dead Sea has dropped significantly in the past 10 years because water began being seriously diverted in the 1960's. By significantly, it must be at least 50 feet, if not more. In the areas that were underwater in the 60's and are shore today, a lot of sink holes are forming. Geologists noticed that they were forming along lines, so there seemed to be a pattern to where they show up. The questions were, why are they forming and where will the next one form?

So the why are they forming has to do with two things: 1. the sediments underground in this area and 2. fresh and salt water interface. So as you can imagine, the layers of sediments and rocks under our feet here at the Dead Sea are a mix of mud and salt. Mud is deposited by water carrying sediment to the sea floor and salt is deposited by evaporation. There are layers where mud and salt are stacked on top of each other, and we are seeing this in our cores, but it was already well known. What is important for the sink holes is that not too far below the surface (20 meters?) there is a thick salt layer.
The other component is water. The Dead Sea is extremely salty and so the salty water dominates the water system depending on how high the Dead Sea is. So back in the 1960's the Dead Sea was much higher and salt water penetrated the ground much higher on shore. The other water in the mix is the fresh water that is coming in from springs and precipitation off of the mountains that border the sea. As you might imagine, there is a place where the salt water from the Dead Sea level meets the fresh water rushing down to the sea. This interface drops as the Dead Sea level drops, so it is much lower now than it was before the 1960's. So freshwater is traveling through more sediments in order to reach the sea, including this thick salt layer. So they think that as freshwater passes through the salt layer it is dissolving it and carrying it to the Sea. Therefore caverns are forming where the salt once was, and it collapses eventually to make a sink hole.
On the other hand we notice that these sink holes seem to be following a pattern on the surface. They are mostly showing up in lines rather than bunches or sporadically. It is thought that these lines are subsurface faults that the water is traveling through. This makes sense because the salt layer may be susceptible to water, but it is surrounded by mud layers that are pretty impermeable. So how is the water getting through the mud layers surrounding the salt layer? Well, if there were faults that cut through these layers then the water can take advantage of the cracks to reach the salt layer and then out to the Sea. Faults are linear features and definitely are all over this area. So that's the idea in principal as I understand it, of course it is always more complicated.
I hope that made some sense.

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