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> July 24 – Iturup and then Kunashir Islands (part 1), or I learn how to be a beach geomorphology geologist.
Misty_Nikula_Ohlsen
post Jul 27 2006, 10:08 PM
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July 24 – Iturup and then Kunashir Islands
or I learn how to be a beach geomorphology geologist.


***** Message from Jesse Einhorn at end of today’s journal *****

Monday, 24 July – Aboard the Gipanis, offshore of Berezovka on Iturup Island
9:00 pm


When I woke this morning, I looked out the window to check the weather, as I do every morning, and I was unsurprised to see that . . . it was foggy. It has been foggy every morning that we have been in the Kurils. Occasionally, it clears up a bit in the mid- to late-afternoon, but it has not ever been clear or very sunny for long.

Today, however, on top of being foggy, it was colder and windier than usual. So right after breakfast, I double checked my pack, refilled my water bottle and dressed in my warm clothes and rain gear, headed down to the aft deck to go ashore. Jody had come down with a nasty head cold and stayed on the ship today, sleeping, drinking tea and recuperating. (She is feeling much better this evening and plans to join us tomorrow.)

We headed to shore with a more fully loaded zodiac than usual (8 people instead of 6 or 7) and immediately got splashed over the front of the boat by 2 or 3 big waves. All 4 people up front huddled up against us in the back as we made the rest of the trip to shore. Luckily, we had (mostly) dressed for the weather!

When we got to shore, while we waited for the second group, we quickly built up a small campfire and worked on warming up and drying off. After about 20 minutes or so, we split into archaeology and geology groups and headed out to work. Today I worked with the geology group and learned what they do to determine how when beaches form (that is, beach geomorphology).

The first task for the geology team was to try and find a good profile of the soil, sand and tephra deposits in this site. We walked along the stream and found some good places where the stream had already partially exposed the profile and began working on digging back into the bank to create a clean and complete exposure. The lower part of the profile proved to be very interesting! There were many layers some thin and some thicker. Bre showed me how we could tell which ones were peat, where plants live in shallow water and when they die there is not enough oxygen for them to decompose so their fibers are still in the dirt layers. We found some seeds in two of these layers that we put into sample bags in case they could be identified by the palynologists later. There was also a thick, gray silty clay layer that Bre said was deposited in a lagoon. On top of that layer was a thin sandy layer that may have been caused by a tsunami.

Above all of these layers was a thick debris flow from a volcano that was about 4 meters thick. It was filled with orangey-red angular rocks of all sizes from sand grains to 30 cm in diameter. It was a mixed up rocky mess! It was amazing to think that all of this material it was all from one volcano, covered most of the valley around us and probably happened in one afternoon!

After we had gone back to the campfire to warm up a bit, we excavated above the debris flow and found some more sandy, soil layers and a couple of smaller tephra layers. On top of the tephra layers we saw a few artifacts – pottery pieces and stone flakes. We finished up our profile work and it was time for lunch. As we waited for lunch to be ready, Beth and I walked down the beach a ways and saw 10-15 harbor seals relaxing on rocks a ways out into the water.

After lunch by the campfire, Jesse, Bre, Beth and I hiked to a dry river valley about 2.5 km down the beach, back toward the caldera that we had seen yesterday. When we got there, we saw an amazing sight! As we came around the steep sides of the valley, on the valley wall that had been cut by the river, we saw an immense volcanic deposit created by a debris flow. This mud, ash, and rock deposit would be similar to some that were created when Mt. St. Helens erupted in 1980. This deposit was 20 meters tall and as we looked around on the other hillsides that we could see on both sides of the valley, it was everywhere. If I thought that a 3 meter debris flow was impressive, this was absolutely stunning. The sheer volume of material that flowed across this part of the island! (See picture below – left)

We decided that we needed to see what was above the debris flow to see if we could match it to our other excavation site. So we walked down to where the dense vegetation (grasses and flowers like we had seen before) came all of the way down to the river bank and we started to climb. By using the plants as hand holds we managed to climb up to the top of the hillside – about 25 meters or over 75 feet, nearly straight up!

When we got to the top, in addition to an incredible view of the densely flowered meadows and tree-covered hillsides farther off, we found a place that wasn’t quite so vertical to climb down a bit from above and worked on clearing a section to see the profile. We were very excited to find a similar pinkish tan tephra layer just below the turf, similar to the one we had seen two days ago in Kuybushevskiy. We also found two other possible tephra layers before we got down to the 4 m debris flow. We precariously perched ourselves on the top of the steep slope and worked on exposing the stratigraphy and describing it. It was so windy that as we worked the wind blew the sand and fine dirt straight up the slope and back into our faces, so we worked from below as much as we could. (See picture below – right)

We were surprised to find that the layers above and below the tephra deposits were only soil, no sand mixed in. This was the first place that we had encountered sand-free soils. In fact, in the last layer before the debris flow, which was nearly 50 cm in total depth, we encountered a fairly textbook soil profile. Soils in most places, like grasslands and forests for example, have four main layers. An organic layer (O), where the plant roots are located, followed by three main horizons – A, B and C – and then the parent bedrock. The A horizon is the one that is a rich mix of organic matter and dirt, tends to be black and can be anywhere from a few centimeters to a meter or more. The B horizon is where the clay minerals begin to collect as they have been washed out of the upper A horizon layer and you begin to see pieces of rock that gradually increase in size. The C horizon is the layer just above the parent bedrock that is a mix of clayey soil and larger pieces of rock that have begun breaking down from the bedrock.

We finished our description of the profile (this time, I did the marking, measuring and describing of the layers while Bre did the recording! My first profile!), took samples of the tephra layers and started back to our landing site. During our hike back we took opportunities to investigate fascinating rock formations that we encountered and Bre measured some, what she hoped to be, marine terraces. Marine terraces are former beach surfaces that have been uplifted by earthquakes or other tectonic actions. She and I had an interesting, but unresolved, discussion about how she could go about testing her hypothesis about the terraces and about where we thought all of the cobble-sized rocks on the beach came from and how they got to this beach. We were also surprised to find several more Japanese glass ball floats on the cobble beach! Surprised because we wondered how they could have washed ashore without breaking. I added mine to my hopefully growing collection of glass floats.

We got back to the landing site just in time to join the first trip back to the ship. Unfortunately, it seems that the first trip is the one where they figure out where the big waves are, because in the last few moments before we were ready to climb up the ladder to the ship, the front of the boat took another 3-4 waves and we got soaked again. Oh well, at least this time we could just change out of our field clothes, get into our relatively cleaner and drier clothes that we hadn’t worn to shore and get warm tea.

Some time tonight, they will raise the anchors and we will make our way across the channel to the north side of Kunashir Island. At least the expectedly rough crossing, given the amount of wind and that the areas between islands have more currents as the Pacific flows into or out of the Sea of Okhotsk, will be while we are already lying safely in our bunks. smile.gif

IPB Image
On the left: Beth is in front of the huge mudflow deposit. The deposit extends from the river bed up to nearly the top of the hillside – a height of 20 meters. The darker, reddish brown strip at the top is the 4 m debris flow that we saw in our first excavation.
On the right: Jesse, Bre and I as we work on the top of the escarpment. Believe me; it is steeper than it looks from this picture! We had to dig in little foot holds to keep from sliding down into the vegetation below.


Mrs. N-O

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A message from Jesse Einhorn home (he wrote it in third person – I’m just typing it in): Jesse misses Amanda and his ears are full of sand, but he’s working hard and having a good time.
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