The day began with a quick breakfast and a walk to the tunnel to start the melting process again. There are a number of rocks that have fallen, tons of debris that have floated along the water way to clear and bore holes to ream. The bore holes are long holes drilled through the granite into the ice which are used to connect instruments. They are full of small rocks and ice and are difficult to get debris free. they require constant working and reworking. An interesting feature on the floor of the opening is an ice bed that has buckled up under pressure. Remember the ice is under terrific pressure down here and in this form it oozes and fills in any void or cavity. When we remove the ice from above the layer of ice below was pressed on the left and right and had no place to go but up. The pressure beneath a glacier is several mega pascals, or about what you would feel if you had your toes stepped on by someone with high heels.
Imagine squeezing a slab of ice with your hands ... with enough pressure it would bend. You do not see this often, but down here the glacial ice walls press with such high pressure on this slab of ice sitting on the bottom of the cave floor that it has lifted and formed an arch.
This opening shows a peak into the vertical shaft, we still need to clear more ice. It takes at least 334 joules of energy to melt a single gram of ice. This is a lot of energy still needed.
This is what the bore hole looks like from inside the cavern. There will be electric cables strung into the hole that will attach to the instruments laid in the ice. As the glacier moves it will drag the cables with it.
The horizontal shaft is now connected to the vertical chamber, inside there are two main hollowed out portions to this cave, enough to move around easily. It is hot and wet.
The bore holes are cleaned from below.
Later in the day we continue some lab work, internet work, and then a helicopter arrives to bring electricians to fix the fire alarm in the tunnel. The new safety measures are very important. We constantly check back at the shafts to see if the melting is going in the right direction and to clean out the boreholes. The vertical shaft is completely clear now and you can peer into the tunnel below. We take a long lunch until Miriam arrives with Ben and Pete from Prof Iverson's group in Iowa. Mark is finishing the accelerometer connections. After dinner, I volunteer to be the night guy. The ice has oozed back into the entry way of the horizontal chamber and needs another three hours of melting which should be done at midnight.I hang around the lab as it melts and work on the internet and then go through the shut down procedure. It is really important to pull the hose and equipment out of the tunnel so that nothing is caught unexpectedly. Also, I have to remember to make sure to shut the emergency flood gate, this is a metal door that prevents water from rushing down the tunnel in the
event that there is a sudden spring melt. It is rather creepy being in the tunnel alone with the rushing water and rocks cascading down the shaft pinging in uncontrolled avalanches. The walk back is a splendid row of yellow sodium lamps strung down the side of a damp gravel road.
This unit will go into the bore hole and measure how quickly the glacier accelerates.
These electricians must be flown up to the glacier by helicopter to work on the fire alarm system for the day.
These reinforced cables will be threaded through the boreholes to make a connection with the instruments moving with the ice.
This is what the rock walls look like in the tunnel.
Tons of rock float out the melt tunnel, this is the bedrock debris from the glacier grinding as it goes down the hill. It is good practice to keep the entry to the horizontal shaft open.
You can see down the shaft now to get an idea of what is going on. In this spot a flat panel of instruments with a granite plate will be placed. The glacier will slide over this plate and measure the weight and the shear on the plate as it is dragged in the direction of the glacier movement.