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Archaeology Update
Today's our day off! Some people have taken the cars off to various other towns, but I'm wandering Sauðarkrokur. I climbed up the hill behind the town and I've found a picnic table where I can sit and write about Viking archaeology!
I haven't decided yet if I'll post this on the official blog. Hmm.
Icelandic dating is easy, in some ways, because of the tephra layers. If we can find tephra, we always know how old things are - or at least what dates they fall between. In some ways this is unfortunate, though, because diagnostic artifacts such as a dated coins are rare in Iceland, so there is no good way to date finds if we can't find tephra to place them in context. Iceland is volcanic - formed by volcanoes and plagued by volcanoes - and with each major eruption, the island was blanketed in a distinctive layer of ash. When we're out in the field taking soil cores, we're looking for anything cultural, of course, and we're also looking for tephra. I'm not wonderful at distinguishing them, but I'm getting to the point where I can make a reasonable guess. Sometimes they're obvious, and sometimes not so much.
The most recent layer that we usually see is from 1766, and before that, 1300. Both of those are usually characterized by thin black lines in a stratigraphic profile. Next are eruptions at 1104 and around 1000, also called H1 and H2, represented usually by thin white lines. Below those we'll find the landnam layer - landnam is the Icelandic word for land-taking, corresponding to sometime in the late 800s, when Vikings were first beginning to colonize the island - there's an obvious change in soil color and texture before vs. after landnam. Landnam tephra is a layer of greenish-black, usually found with several centimeters of really colorful stripy soil. Finally, H3 and H4 are prehistoric tephra layers, and are very thick and white. Full sequences are really pretty - I'll try to get a picture before the end of the summer.
We're interested in settlement patterns in the middle of the Viking era, so we're looking especially for the 1104 and 1000 tephras, and for anything cultural between those layers and landnam. At Pafastaðir we're putting a 1x1 square into the giant midden - we're already down more than 1.5 meters, and we haven't reached 1104 yet!
Sometimes we'll see a core profile that looks confusing - multiple criss-crossing layers of the same tephra, or one with no tephra between 1300 and H3/4. In the second case, that would mean we've found a bog area that was cut for turf sometime between 1104 and 1300. In the first case, layers of criss-crossing tephra, out of sequence or upside-down, means we've found a turf structure! That's what we're really hoping to find. No luck so far, though. Then, if we can determine which tephra is in the cut turf, we have a terminus post quem (date after which) for the structure; if there's a layer of tephra above the wall, we have a terminus ante quem (date before which).
Turf is cut from the top layers of a peat bog, and then left to dry in the sun before being used as a bulding material. There are several different ways to cut it, depending on how it will be used, but I don't exactly remember, so I won't go into that. It's very light when it dries, much lighter than sod, because it's composed of densely packed sedge roots and not so much soil. It's also quite hard when it dries - turf walls are very solid. They're not terribly good at weight-bearing, though, so turf houses usually have a wooden frame that supports most of the weight. Driftwood, of course, since trees are so rare on the island. When the wood structure starts to rot or buckle, that's when the house really begins to collapse.
The turf house that we visited at Tyrfingsstathir was actually lived in up until the middle of the last century - it was wired for electricity and indoor plumbing and everything. Now it's falling down and is used both as an example of a decaying turf house and for teaching people how to build with turf. There's a bog close to the fjord where turf is cut, and as each class comes through they're slowly rebuilding the house and outbuildings. We walked through a reconstructed sheep barn very similar to the one we're excavating at Seyla.
To repair turf walls, first the old turf walls are sheared off straight on all sides. It looks like a big layer cake, with layers of tephra, dried grass, and turf. Then new turf is stacked around the old turf. Walls get thicker and thicker, and become increasingly better insulators.
Wall profile with tephra. It's hard to see all the layers in the picture. I think the white stripe at the bottom is the 1104.
This is the beginning of our big hole at Pafastathir. 1766 is being uncovered in the left corner.
Tyrfingsstathir.
A pile of cut turf.
A turf wall that has been cut straight on all sides.
A peat bog that has been cut.
Going into the sheep barn.
Inside. The sheep would stay in here all winter, being fed through the hole. Then when spring came they'd let the sheep out and muck out the building.
A turf wall showing the herringbone pattern.
Inside the more modern part of the turf house.
Another view of Tyrfinsstathir.
Wooden supports collapsing beneath dandilions.
Unrelatedly, if you guys would like pictures of anything in particular from Iceland, let me know and I'll do my best!
I haven't decided yet if I'll post this on the official blog. Hmm.
Icelandic dating is easy, in some ways, because of the tephra layers. If we can find tephra, we always know how old things are - or at least what dates they fall between. In some ways this is unfortunate, though, because diagnostic artifacts such as a dated coins are rare in Iceland, so there is no good way to date finds if we can't find tephra to place them in context. Iceland is volcanic - formed by volcanoes and plagued by volcanoes - and with each major eruption, the island was blanketed in a distinctive layer of ash. When we're out in the field taking soil cores, we're looking for anything cultural, of course, and we're also looking for tephra. I'm not wonderful at distinguishing them, but I'm getting to the point where I can make a reasonable guess. Sometimes they're obvious, and sometimes not so much.
The most recent layer that we usually see is from 1766, and before that, 1300. Both of those are usually characterized by thin black lines in a stratigraphic profile. Next are eruptions at 1104 and around 1000, also called H1 and H2, represented usually by thin white lines. Below those we'll find the landnam layer - landnam is the Icelandic word for land-taking, corresponding to sometime in the late 800s, when Vikings were first beginning to colonize the island - there's an obvious change in soil color and texture before vs. after landnam. Landnam tephra is a layer of greenish-black, usually found with several centimeters of really colorful stripy soil. Finally, H3 and H4 are prehistoric tephra layers, and are very thick and white. Full sequences are really pretty - I'll try to get a picture before the end of the summer.
We're interested in settlement patterns in the middle of the Viking era, so we're looking especially for the 1104 and 1000 tephras, and for anything cultural between those layers and landnam. At Pafastaðir we're putting a 1x1 square into the giant midden - we're already down more than 1.5 meters, and we haven't reached 1104 yet!
Sometimes we'll see a core profile that looks confusing - multiple criss-crossing layers of the same tephra, or one with no tephra between 1300 and H3/4. In the second case, that would mean we've found a bog area that was cut for turf sometime between 1104 and 1300. In the first case, layers of criss-crossing tephra, out of sequence or upside-down, means we've found a turf structure! That's what we're really hoping to find. No luck so far, though. Then, if we can determine which tephra is in the cut turf, we have a terminus post quem (date after which) for the structure; if there's a layer of tephra above the wall, we have a terminus ante quem (date before which).
Turf is cut from the top layers of a peat bog, and then left to dry in the sun before being used as a bulding material. There are several different ways to cut it, depending on how it will be used, but I don't exactly remember, so I won't go into that. It's very light when it dries, much lighter than sod, because it's composed of densely packed sedge roots and not so much soil. It's also quite hard when it dries - turf walls are very solid. They're not terribly good at weight-bearing, though, so turf houses usually have a wooden frame that supports most of the weight. Driftwood, of course, since trees are so rare on the island. When the wood structure starts to rot or buckle, that's when the house really begins to collapse.
The turf house that we visited at Tyrfingsstathir was actually lived in up until the middle of the last century - it was wired for electricity and indoor plumbing and everything. Now it's falling down and is used both as an example of a decaying turf house and for teaching people how to build with turf. There's a bog close to the fjord where turf is cut, and as each class comes through they're slowly rebuilding the house and outbuildings. We walked through a reconstructed sheep barn very similar to the one we're excavating at Seyla.
To repair turf walls, first the old turf walls are sheared off straight on all sides. It looks like a big layer cake, with layers of tephra, dried grass, and turf. Then new turf is stacked around the old turf. Walls get thicker and thicker, and become increasingly better insulators.
Wall profile with tephra. It's hard to see all the layers in the picture. I think the white stripe at the bottom is the 1104.
This is the beginning of our big hole at Pafastathir. 1766 is being uncovered in the left corner.
Tyrfingsstathir.
A pile of cut turf.
A turf wall that has been cut straight on all sides.
A peat bog that has been cut.
Going into the sheep barn.
Inside. The sheep would stay in here all winter, being fed through the hole. Then when spring came they'd let the sheep out and muck out the building.
A turf wall showing the herringbone pattern.
Inside the more modern part of the turf house.
Another view of Tyrfinsstathir.
Wooden supports collapsing beneath dandilions.
Unrelatedly, if you guys would like pictures of anything in particular from Iceland, let me know and I'll do my best!
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