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> July 25 – Iturup and then Kunashir Islands (part 2), or I learn how to be a beach geomorphology geologist.
Misty_Nikula_Ohlsen
post Jul 27 2006, 10:09 PM
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July 25 – Iturup and then Kunashir Islands
or I learn how to be a beach geomorphology geologist.

Tuesday, 25 July – Aboard the Gipanis, offshore of Lovtsova Peninsula in Spokoynyy Bay
8:30 pm


Today, I learned more about what beach geomorphology geologists do and also learned a bit about the unpredictable nature of field work.

This morning, cold and foggy as usual, we anchored off of the south side of Lovtsova Peninsula. We are in the Pacific Ocean! We went to shore in our two trips of the zodiac as usual, this time without too much dampness on the way in. As we waited for the second zodiac group, Jody got to work and quickly excavated an eroding beach bank.

A few minutes later, we learned that the second zodiac group had landed further down the beach from us (we hadn’t seen them in the fog), so we walked down to meet up with them. At that point we set out to find some good places to work for the day – the archaeologists looking for evidence of dwellings (they apparently went a wild goose hunt today) and the geologists trying to determine the history of the beach ridges.

Beaches have a few typical characteristics. First there is the slope of sand or cobbles that reaches down to the surf. On most beaches you can locate the high tide line as the place where the driftwood and other debris is left as the tide recedes. Somewhere above that is the storm line, where the winter storms deposit really big stuff like large driftwood logs, etc. Typically, near this area is the first beach ridge. This is the berm of sand or rocks that forms at the upper edge of the active beach area and often is where the vegetation begins. If a beach is uplifted or the sea level changes then that beach ridge might be abandoned and a newer beach ridge forms in front of it on the new active beach. There is then a trough that is formed between the old beach ridge and the new active one that is the former beachfront. The sizes of the beach ridges and the number of ridges depends on lots of different factors, like the rate and amount of sediment being removed or deposited on the beach, how often there is uplift or sea level changes, tsunamis, the number of storms, etc.

On this particular area of Kunashir, there were several beach ridges of different heights stretching about half a kilometer from the beach. We set about doing two things to learn more about this area of the coast. First, Jesse and Beth set about digging large holes down into the trough areas between the old ridges. The holes were about 1 meter wide, 1.5 meters long and as deep as they needed to be – typically 1-2 meters. This was a lot of dirt to move with a shovel! While they worked on this, Bre and I set about measuring the horizontal beach profile.

To do this we used an instrument called a "nievelier" (level in Russian). It is basically a surveying instrument that allows you to take a very level measurement over a long distance. By looking through the instrument and sighting a tall rod with measuring marks on it you can determine, by comparing the measurement on the rod with the height of the instrument, what the elevation of the place where the rod is relative to the instrument. Then by using the idea of similar triangles and some appropriately placed marks in the sight, you can also determine how far away the rod is from the instrument. By taking a series of measurements from the beach surf up and over the sequence of ridges you can construct a diagram of the horizontal profile of the beach. You can move the instrument further up the transect line by “leap-frogging” it over the rod and taking a measurement from both sides that can be matched up on the diagram. (See picture below – left)

At first, it was very slow going because the wind was blowing the fog onto the lens of the instrument. But as we worked, we became more efficient. The entire profile took about 2 hours.

After we finished the profile, we rejoined Beth, Jesse and Jody who were working on describing and sampling the vertical profile that Jesse had exposed in the hole that he dug. Jody was down in the hole, measuring the widths of deposits and describing their color, grain size and composition. (See picture below – right).

At this point we learned that lunch was not coming to us today. While we have been on shore, everyone usually stops working and heads to the beach some time about 1:30 pm to have lunch. Well, we were at least 25-30 minutes from the beach, so we would have lost a lot of our work time if we made the round trip there and back, so we decided to make due with the snacks and food that we had in our backpacks – Cliff bars, a stale cheese sandwich, chocolate-covered espresso beans and a leftover piece of Russian pizza (hot dogs, mushrooms, tomatoes and cheese – quite delicious cold, actually). Ah, the food of kings!

After our spare repast, Bre and I walked back to the first beach trough and worked on digging our own excavation. We worked for about 2.5 hours and dug a hole about 1 meter by 1.5 meters and about a meter deep. We then described the layers and found possibly one or two tsunami deposits. We didn’t have enough time to dig all the way down to find beach sand, since we needed to be back at the zodiac by 5:30. So we quickly finished out work, packed up all of our gear and trekked back up the shore. (Yes, we looked for glass balls and found MANY! The Pacific side is more profitable than the Sea of Okhotsk side. Beth found so many that she had to stop collecting them, even.)

Now, we are all safely back onboard the Gipanis, clean and dry, with full bellies once more. However, we are still anchored here offshore and the swell of the Pacific Ocean is causing the boat to roll side to side quite dramatically. I am working on this journal post while lying in my bunk, since sitting at my desk seems to make me feel much queasier. I haven’t had much sleep in the past two nights, so I think that I will sign off here and head to bed soon.

IPB Image
On the left: Bre MacInnis is working to set up the survey instrument – it is on top of the tripod. She will need to level the instrument with the tripod before we can take a measurement. She is taking the scaled rod out of its storage bag.
On the right: Jody Bourgeois down in the hole that Jesse Einhorn dug, describing the cross-section of deposits. There were several tephra layers, some volcanic cinder layers and at least 2-3 tsunami deposits (beach sand). This excavation was nearly 500 meters from the current beach front.


More in a couple of days!
Mrs. N-O
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