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18 July, 2000

July 18, 2000

Matanuska Glacier, Alaska

I finally got a good look at the moose and calf that have been seen in this area recently. As I was coming back from uploading pictures on Sunday night I luckily happened to notice them before getting too close. Cashman and Josh accidentally got too close to them one morning before I arrived and she charged at them to protect her calf. It was nearly 10:30 at night and with the thick clouds and the late hour it wasnít very bright out. They almost blended into a pile of slender spruce logs that had been stacked next to the gravel airstrip here. Both of them were frozen in place and looking at me. I paused for a minute and then decided to back up a bit before heading off down the side of the airstrip, perhaps fifty yards from them. I kept watching as they disappeared behind the pile. I eventually could see that the cow had come to the other side of the wood pile to keep an eye on me. I continued on my way back to camp. About a week ago I was entertained by the warning barks of a fox in this same area, also late in the evening. Perhaps some night I should stay up and go for a long hike!

The weather finally improved a bit today and got quite nice for awhile. It was a nice break from the past week or so. Yesterday evening it felt especially cool with a constant strong wind whirling through camp.With the clouds and cooler temperatures of the past week you can really tell the melting on the glacier has decreased significantly. All the vents and rivulets are much slower than they had been.

Last night we discussed our project with Jeffrey Strasser and it was decided to proceed aggressively with the dye tracing experiment. We will wait until Thursday to try our first experiment so that we can take advantage of the extra manpower that will be available when all the REU students are here. At that time we will have four ISCO water samplers to place in different vents, ones that we feel have the best chance of the dye draining through. We want to try to establish the moulin/vent connection quickly and sample as many as possible. Once thatís accomplished then we wonít need but one or two at the vent or vents that turn up with the dye.

Initially we will dump just one bottle of dye as it is thought from past attempts to be sufficient. We will then dump more if necessary. We plan to dump into the same moulin that we have with the salt in earlier tests. We will also keep the current ISCOs at Trail Vent and Little River Vent. The other two will be placed at two of the more active vents in the Mammoth Vent area.

We went to this area of vents today with Cashman to look things over. The flow from the vents has decreased significantly recently and we needed to evaluate our placement. In spite of reduced flow there is significant amounts of frazil ice forming from the supercooled vent water. It appeared at first that one of the CTDís attached with the ISCO tube had frozen in but Ben eventually got it to spring free. Every time the devices are pulled from a vent they must be cleaned of this ice that grows on the ropes and instruments to prevent their getting frozen in. It reminds me of growing crystals in chemistry class at school as every day the thread suspending the seed crystal needed to be cleaned of the new crystals beginning to form along its length . Crystals can only form onto existing surfaces and this frazil ice is no different, growing on the instruments and extending from rocks and ice around the vents. Eventually frazil ice may form ice terraces out from the surface of the water much like mineral terraces form in Yellowstone. That hasnít happened here yet, but Iím hoping to get to see that form some day.

Marvin Giesting


Ben Cashman pulling in the CTD and ISCO tube from one of the Mammoth Vents. They've been called this not due to the size of any one vent, but because there are numerous vents concentrated in a small area here.


Quite a bit of frazil ice can form on the instrument and ropes in just 48 hours in a vent.


A piece of frazil ice taken from the CTD. It appears to have flat, tongue-like crystals of ice sticking out.


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