  [Intro] [Overview] Page: Page 3ANNOTATED NOTES FROM SUMMER, 1998 FIELD INVESTIGATIONS IN ALASKA
Thursday, June 25: Had a final breakfast at Taylor’s fine base camp, said our good-byes, paid our bills, and headed south on the Taylor Highway. It is slow going, with lots of turns, and it is in some places pretty rough gravel. It seemed to take forever to get to Chicken, where we stopped briefly at Lost Chicken Hill Mine to take a look at the ongoing gold placer operations.I last visited the mine in 1991 with a team of scientists from USGS and Geological Survey of Canada. The original mine owner we met in 1991 has died, so the mine is now owned by his daughter and her husband. There are lots of placer mines in interior Alaska, but this one is of particular interest, because the exposures in the mine are untypical. The frozen sediments that are being washed away in this mine include some Pleistocene deposits, as commonly occurs in interior Alaska, but there is also a substantial thickness of ca. middle Pliocene to perhaps late Pliocene age fluvial gravels, within which are lenses and layers of peat, well preserved logs, some of which are stumps in original growth position, and there are also two or three tephras exposed. The placer operations that have occurred since 1991 have changed the exposures substantially. It appears that there is now a substantial thickness of Pleistocene silt and peat exposed in the upvalley end of the exposures. I don’t recall seeing that in 1991. We had little time to explore the sections, and they were actively washing some of the exposures with high pressure streams of water from "giants." The exposures are mostly vertical and unstable, so it is a dangerous place to work, near the face of those thawing exposures. We did manage to collect maybe 5 samples of peat and a couple pieces of stumps from within the Pliocene deposits. One peat sample came from a ca. 1.5 m thick peat that I suspect may be last interstadial or possibly last interglacial in age (late Pleistocene) near the top of the section on the upvalley end of the exposures. We spent the afternoon driving the rest of the way to Tok, then to Delta Junction. The day had started out sunny but by mid afternoon we were back in heavy rains. We found what may have been the last available motel room in Delta Junction, so we grabbed it. We found a local restaurant for dinner, and then spent the evening writing notes and calling home to check in. Fortunately, everything is ok at home. It seems like I have been away a long time already. Friday, June 26: Drove from Delta Junction to Fairbanks and went first to make sure our motel reservations were not screwed up. We moved into our rooms, then spent the day running errands. We returned the rental satellite phones, and drove to the mini-storage place where we loaded our gear back into the air freight containers and sealed them up. We then drove about 4 loads of loaded air freight containers to the Alaska Airlines air freight terminal at the airport so we could ship things to Ketchikan. That took a while, but we got the paperwork done and the freight is on its way. We then packed up samples we collected near Mount Harper and sent them back to Denver via Federal Express. Sharon Van Loenen arrived from Denver to help us out for about a week. I tried to find her at the airport but she was not on the flight I expected her to arrive on, so I went back to the motel. She came in on a later flight and arrived at the motel in the motel’s shuttle van. We were all pretty worn out at the end of this long and busy day. Saturday, June 27: Having taken care of our most urgent chores, we now have some time to spend in the Fairbanks area until we head for southeastern Alaska. We spent part of this day over at Great Northwest, Inc., a peat mine adjacent to College Road on the north edge of Fairbanks and about 0.8 miles (1.3 km) east of the University of Alaska campus. Dan Muhs, Josh Been and I had visited this mine last September and collected samples in peat exposures that turned out to span about the past 5500 years or so. But there was frozen peat extending to below the water level in the pit that I was unable to sample with the equipment we had available. Frozen peat is about as hard as concrete. The mine operates by bulldozing off layers of thawed peat, scraping down until they hit the frozen upper surface of the permafrost. Then they move on to another area, and come back to the old areas after the permafrost has receded another foot or two. They process the peat for use in greenhouses, farms, and local gardens. During this visit, it was clear that the permafrost table had retreated since last September, but the water in the bottom of the pit prevented me from digging into it to sample it. The holes I tried to dig would fill with water very quickly. It will require a peat corer to penetrate this. It would be interesting to penetrate to the bottom of the peat deposit, in order to put together the Holocene pollen record for the Fairbanks area in some detail. There is a good chance that there could be a record here going back to maybe 8000 years or so. Unfortunately, my peat corer was shipped directly from Denver to Thorne Bay on Prince of Wales Island. I didn’t think I would need it in interior Alaska this summer. Perhaps Dan Muhs will be able to core this for me the next time he visits Fairbanks. (Note added in September: Dan Muhs plans to visit this site during his visit to Fairbanks later this month, and will take along his soil auger to see if he can recover the bottom meter or so of this peat section). Last year I sampled here through about 3.6 meters of mostly fibrous peat. Some is derived from sphagnum moss, and some is sedge peat. There are zones with well-preserved wood, some of which is small tree sized (probably black spruce) and both last year and this year I found layers of very well-preserved cones of black spruce. The layer I found this year was only 1.2 meters below the present ground surface. This year I noticed that there are some Larix laricina (larch) trees growing in the present bog, in addition to the abundant Picea mariana (black spruce). At a depth of 320 cm I found a cone of Picea glauca (white spruce), so perhaps it was a less boggy site at that time. At that depth the deposits are probably about 5000 years old. This deposit is of interest because there is no detailed record of vegetation changes for the Fairbanks area during the late Quaternary, especially for the Holocene, just a fragmentary record based on data from several scattered localities in the Fairbanks area . This deposit may provide the first fairly detailed record for the area for at least much of the Holocene (the Holocene spans the past 10,000 years). Another reason why this record is of interest is that surprisingly little is known about peat accumulation rates and volumes in interior Alaska. Peat deposits contain a huge amount of carbon, which if released by burning or slower oxidation, would contribute a lot of carbon dioxide and methane to the atmosphere. So this site may provide us with a little information about the history of peat accumulation in this area. Sunday, June 28: Warm, sunny day. We decided to spend the day back at a placer mine near Fairbanks, so I called the mine owners for permission to enter their property. As usual, they were very cooperative and friendly. We drove into the site and found a miner operating the "giant" in the upper end of the valley. We exchanged greetings and a short time later he shut down his hydraulic system and left. I think he was running out of water from the pond that feeds into his "giant."
We climbed up to the trench that Dan Muhs, Josh Been and I had dug last September to have a look at it again myself, and to give Larry Phillips a chance to look at this thick loess deposit. The exposure is nearly 40 meters thick, and very steep. There are frequent small landslides that occur very suddenly, so you have to be on the alert to avoid the most hazardous areas. I was able to relocate several of the key paleosols (ancient buried soils) exposed in the trench. Some of the soils are pretty young forest soils that are about 8500 years old or younger, but a bit lower in the section there are several soils that seem to represent tundra soils dating to the mid-Wisconsin interstadial, a time of unstable climate prior to the onset of the last major glacial interval. Those interstadial soils are about 30,000 to more than 50,000 years old. I resampled several of these old soils in hopes of recovering more usable pollen samples. I also had a chance to look at newly exposed sediments near the base of the section, where recent washing operations exposed the dense silt unit that immediately overlies the coarse gravel that sits on top of bedrock in this area. I saw a few bits of carbonized wood in those basal silts, but I saw nothing that looked worth sampling for pollen analysis. But seeing those basal sediments allows me to fill in some missing information from the measured section I attempted to work up from our trench exposures last September. Slumped material at the base of this section was too thick to remove, so I was unable to see what the lower ca. 6 meters consisted of. There is still a gap in the record, because I still have not yet seen everything within that 6 meter covered zone, but I can fill in perhaps half of that gap. I think that the samples I collected here today will help fill in some of the gaps in radiocarbon dates and perhaps pollen data that we have been accumulating from this area for the past couple of years. Monday, June 29: We packed up our gear, checked out of the motel, mailed off some boxes of samples to Denver, and ran a few errands. Then we headed for the airport to return our rental vehicles and wait for our flight to Anchorage. We got to Anchorage in late afternoon and had to wait a couple hours for our flight to Ketchikan. We finally got on board and took off towards the southeast. Initially visibility along the coast was pretty minimal, but it began to clear as we passed the coast near Bering Glacier.
But the route followed by the jet was so far from shore that the view of the coastal mountains was at a great distance. Then we were in and out of clouds as darkness descended. It was a bit surprising to see real darkness again. We have come far enough south to get into shorter day lengths. We flew into the airport on Gravina Island, across a channel from Ketchikan. It was dark by the time we landed, and it had been a pretty long day for us. I have never been to Ketchikan before, so I did not know how to get to our hotel, but had some vague directions from the young man at the car rental desk. I rented a car at the airport, and we somehow shoehorned all 5 of us into the car with all of our back packs, duffel bags, rifle cases, and other junk. It was a very tight fit, and most of my passengers sat with large duffel bags in their laps. We had to wait to board the ferry boat that runs between the airport and Ketchikan about every half hour. Once we drove off the ferry we wandered around Ketchikan in the dark and discovered that our directions to the hotel were too vague to be useful, so we stopped for directions, finally. Guys hate to ask for directions, but Sharon was with us, so what could we do? With the help of directions from a grocery store clerk we found our hotel at last, on a hill overlooking part of downtown Ketchikan and the waterfront. Quite a lovely view. It was about midnight by the time we got to our rooms.
Tuesday, June 30: We assembled in the hotel lobby and met up with Jim Baichtal, the geologist who works for the USDA Forest Service on Prince of Wales Island. He had flown over the day before to meet with us and to spend the day looking at uplifted marine exposures that he knows about in the Ketchikan area. We are interested in finding out more about the history of isostatic rebound of the crust following retreat of glaciers from the Ketchikan area. The great thickness of glacial ice depressed the crust substantially in some areas during the last glacial interval, that ended roughly 13,000 years ago. When the ice first receded, marine waters rushed in and marine deposits accumulated that were still heavily influenced by sedimentation from the retreating glacier fronts. Then as the crust rebounded the marine waters receded in many areas. We may be able to obtain radiocarbon dates on the marine shells within the glacio-marine deposits, and we can also date the base of the peat units that overlie the marine deposits. We can also attempt to analyze the oxygen isotope ratios preserved in the marine shells we date, so that we may be able to reconstruct a history of temperature changes in the marine waters near Ketchikan following deglaciation.
After breakfast we headed over to the Forest Service building to meet up with some additional Forest Service people, such as Dennis Landwehr, a soils scientist for the Ketchikan district. We first visited an exposure behind some buildings at the southern end of Ketchikan. Baichtal refers to this site as the "Schmolck" section, based on the name of a business located adjacent to it. Some of the previously exposed sediments had vegetated over or had been eroded away or had been covered over by construction activities, but what we could see indicated that there was about 15 cm thickness of exposed dark gray marine clay with shell fragments of about 3 shell types. The clay layer overlies about 30 cm of gray sandy silt that contains no visible shell material. Below that is about 40 cm of exposed sand. Based on previous visits to the site when it was better exposed, there is about 15 meters thickness of sand in this unit at this locality. The next site is referred to as the Shaub Tire Store site. Behind the store is an exposure of artificial fill overlying a layer of woody peat that is about a half meter thick. The peat overlies a gray silt containing plant detritus about 10 cm thick. Below that is a peat layer about 10 cm thick. Below that is another ca. 10 cm of silt overlying a meter of gravel with a silty matrix, probably glacial till. The "till" unit is sandier towards the top. We saw no shell material at this site. I collected 6 samples here for possible pollen analysis. All the samples were from the units overlying the glaciomarine sediments.
The next site is called "Valentine’s Quarry" north of Ketchikan. It is roughly 130 feet (40 m) above sea level, but that altitude has not been carefully determined yet. In this exposure there is about a half meter of disturbed material overlying ca. 80 cm of fibrous brown peat containing some tree sized wood. Below the peat is a boulder concentration that overlies a gray dense clay containing glacial cobbles plus shell fragments, and some appear to be in growth position. There is about 2 meters of this glacio-marine deposit exposed in the quarry, but it seems to be sitting on metamorphic bedrock. I collected a few samples here, mostly from the shell-bearing marine clay. We then visited the so-called "lighthouse quarry" also north of Ketchikan. At this site we saw exposures of about 170 cm of woody, fibrous peat over sand that in turn overlies about two meters of clay that contains barnacles and bivalves. I collected 16 pollen samples from the upper part of the section (peat) and shell samples from about 87 cm below the base of the peat, within the clay unit. This site is about 140 feet (43 m) above sea level (measured approx. to top of peat unit). Wednesday, July 1: Left hotel at 7 a.m. and drove to Taquan Air Service’s sea plane base along the Ketchikan waterfront. Sharon Van Loenen stayed behind in Ketchikan to fly back to Denver. We crammed 4 of us (myself, Larry Phillips, Josh Been, and Jim Baichtal) and all our gear into a float plane and took off for Thorne Bay. It was a beautiful clear day, sunny and fairly warm...unusual for Ketchikan, which is infamous for its heavy rainfall. It receives about 160 inches (400 cm) of precipitation per year on average. That is about 10 times more than we get in the Denver area. The flight skirted the coastline and we caught glimpses of fishing boats, large seagoing cargo vessels, forested islands of all sizes and shapes, and the many embayments along the coasts of the larger islands.
We landed at Thorne Bay and offloaded our gear at the dock where the float plane tied up. We got a Forest Service truck to haul our junk up to the housing facility we will be using for a while. It is a two story dormitory style building owned by the Forest Service to house seasonal workers, fire crews, and visitors. It has showers and a communal kitchen, and laundry facilities, so this place will work out very well for us. We are very grateful to have access to such a facility. Later in the day we returned to the dock at Thorne Bay to meet another larger float plane (a turbo-beaver) that flew in from Ketchikan with our 1300 lbs. (590 kg) of air freight we had shipped from Fairbanks a few days before. It is a pretty big and powerful float plane, but our air freight filled up most of the plane. The fellow who oversees the flight arrivals and departures hauled our gear in a cart pulled by an all-terrain vehicle up the steep ramp to the parking lot. We have an embarrassing amount of gear to haul around. We loaded the gear onto a pickup and hauled it all over to the Forest Service warehouse. The Forest Service has generously provided us with storage space in their warehouse for our air freight crates and anything we don’t need to haul around with us. We unpacked our crates and reorganized things for the next phase of our work. That pretty much used up the day. Bottom of Page 3 [Intro] [Overview]
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