July 12, 2012 Karst: The Ground Taketh
Thursday proved to be an excellent first full day in Isfjord Radio. The schedule was/is as follows and will remain:
6:30: Rise and shine, shower (probably), decide on outfit, function not the other… 7:15: Exit Polarbrokka, look both ways for polar bears, enter Main building 7:20: Check internet while no one else is on, post (hopefully) 7:30: Coffee, thank god. 8: Breakfast, make lunch of 3 sandwiches minimum, fit in little keilbasas in any tupperware pore spaces. 8:40: Gather gear, people and meet. 9:15: Depart on foot loaded to the gills for field area, hike 5k. 10:15: Field work, hiking, carrying heavy objects, loading boats, hiking, geology... 4-5: Think about getting in boats to shuttle back for hike. 5:30: Better be hiking. 6:30: Clean rifles 7: Dinner, thank god. 8: Meet to go over logistics. 9:15: Free time…blog… 10:30: Book 10:32: No more book, sleep (hopefully) Rinse & Repeat
By the end of the day everyone is red-faced, tired, and sufficiently mellow.
On this first field day we mostly shuttled gear out to the field area by filling every pack plus some donning a frame pack with gas cans or small rafts to be used on the numerous smaller lakes in the area. These lakes will surf as the primary projects for the UNIS AG212 students as well as Sara's masters thesis. They are fairly small rubber rafts with solid floors that make for great floating work spaces. Plus, when you unload it off your frame, you get to wear the frame pack in front and the whole world is like a movie (see Lucas as an example).
We dropped off one boat at a pond closer to Isfjord Radio than Lake Linne then proceeded to Linne to ferry across and check out the main area of small lakes just northeast of Lake Linne. Oh, and our patch jobs held on the boats which had minor (no such thing) holes.
The rest of the day was spent gaining an idea of the field area geology and landforms as a large group. Thus far our progress should seem like a slow crescendo to gathering live time data. These longer field seasons (6-weeks) require not only the preparation aspects I've detailed but also significant in-situ (fancy scientific word for in place) education live time. To be completing large scale projects or writing a thesis on such a place means you've got to know the whole story to gather meaningful data.
The whole story or as much as I can get across reasonably…
I'm sure everyone has exhausted Steve's .pdf on the glacial history so I won't bore you too much here. The entire valley that Lake Linne inhabits was covered by a larger scale glacier during the last glacial maximum. Then, as things started to heat up into the current interglacial that is so nice and toasty the large glacier retreated (~10k years bp) and the valley itself likely only had the smaller valley glacier inhabiting it and receding. During that time the land was depressed from all of the weight of the glacier pushing down on the crust like pushing an ice cube down in a drinking glass. Therefore, the ocean that is no a decent walk from the lake flooded inland making the valley into a bay. Over time the land rebounded back up, sea level fell and sands from outside the valley migrated in due to a process called longshore drift and the lake was eventually cut off from the sea. In addition, many more sands and gravels created beaches in front of the lake that were left high and dry as the ocean fell back closer to its present level and on those areas are the smaller lakes which Sara and the UNIS AG212 students are studying. Enter: Karst.
Karst is a geologic descriptor fairly foreign to most in Maine. Meaning the dissolution of bedrock (usually Carbonates) and ensuing subterranean space/cave formations, it is something alive and well in Svalbard. As you travel west to east across the skinny axis of Lake Linne there is a contact between two different types of bedrock, a quartzite to the west then carbonate rocks to the east. The quartzite being a metamorphosed sandstone is rather resistant to selective weathering and erosion. The carbonate however has proved not so stalwart. Under the large terrace of old marine beaches separating Lake Linne from the coast this carbonate has dissolved in many areas and the bottom has quite literally fallen out from the landscape. What has been left are areas where small lakes fill the low lying areas with no outlets. Instead these lakes have been draining both their water and massive, massive amount of sediment directly into voids in the ground. Note: not all water bodies flow nice and neatly, join together and head to the sea. These go to places we yet know and are connected through conduits we are trying to figure out in the bedrock below. Some indications that we know these are karst in their nature are 1. Mike and another UNIS professor Hanna have traveled out in the winter and seen massive ice blocks alone where the lake once was meaning it was there to form ice and then randomly drained into the subsurface (presto drain!). 2. There are stream inputs into most of these water bodies that are no insubstantial and the water levels aren't rising concomitantly. 3. The gravel walls bordering some of these lakes are constantly being eroded from their base leaving slopes at the angle of repose with no other form of erosion to account for the fresh falling faces (no stream eroding it like a river back). So, in short, these things are mysteries with a story to tell. How much water varies through the system? How much sediment has been flushed to nether-regions? Hmmm…
In addition to the lakes, there are many areas of the ground randomly giving out and depressions where the surface sediment has subsided. Usually these are seen as areas where the finest sediment has gone first and the larger stone are sorted out and left in the depression.
Another especially fun aspect of the carbonate rocks (other than their disappearing act) is the fact that they are derived from ocean sediments and are chalk full (get it, like limestone? sorry) of marine fossils! Not exactly what we're after but a fun distraction)
For an idea of just how much sediment is being drained from these Karst systems check out the picture below. That whole area was likely one nice and broad raised marine beach terrace, called a strandflat, extending from the upper level on the left to meet the right side. Add karats to the picture and it gets completely drained out and looks like a false river valley.
As Mike says, this day was packed full of geo-concepts and he likened it to the students as "drinking from the fire hose." By 5:30 we were all tired and it was time to hit dinner…arctic char, yes. Cue boat taxi time and somewhere between a salute and looking for the other, we made it, hiked, ate, and slept…