Digging in Salt Lake City, July 17-21, 2005 blog archive

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Digging in Salt Lake City, July 2005!

This is the excavation blog from the second week of the dig. Tim Scarlett, Chris Merritt, and guests will post their thoughts and images here as the dig moves ahead over the month of July. We'll let you know what we think we've learned and "what it all means" as we dig deeper into the earth at the Petersen Pottery. You can jump directly to the most recent entry by clicking here. Enjoy!

Jump back to the excavation blog week 1.

Jump ahead to the excavation blog week 3.

July 17th, 2005: Timothy Scarlett

A beautiful day for digging today! Chris and I worked this morning and quit at noon for a paperwork and strategy meeting. It seemed like we spent the morning doing more debating about our strata than actually moving dirt. We finished our photos in 0N0W and then removed the last of the clinker layer there. The layer underneath is now fully exposed. We've been struggling to interpret the difference in the artifact distribution in the units. 0N0W, especially in the most southern corner, seems to have something different happening, but the sediments simply don't show any difference to indicate something occurred. I think we figured it out by lunch, however. It seems that we placed our excavation grids, by blind luck, so that the building foundations just appear in the eastern and southern walls. We just barely clipped the outside edge of these features. As a result, the stratigraphic layers appear to stretch consistently across all four grids, but when we look at the southern profile, those strata are not there. We're going to figure out a way to test this theory tomorrow, but I think that is why we've been confused when looking at the profiles. The artifacts seem to be concentrated around the building's footprint, rather than evenly spread across the yard.

Chris's digital camera has a chip on the lens, and that has been the heart of some of our problems with his camera. We're trying to borrow a replacement, and we'll do our best to keep getting good pictures for this blog.

Chris and I started to talk about Context Units and the Harris Matrix today. These are tools of logic that archaeologists use to explain how soil layers relate to each other in time. First, we've begun to use Context Units (or CUs) instead of levels when we speak of our excavation. When we have several soil layers that appear in different units, like the clinker layer and the hard packed clay layer, sometimes they can have different level numbers. For example:

Sample stratigraphy in two hypothetical excavation units, one dug by Pete and one by Megan.

Pete's Grid	Megan's Grid
Green (1)	Yellow (1)
Yellow (2)	Blue (2)
Brown (3)	Brown (3)
Red (4)	Red (4)
Purple (5)	Purple (5)

Archaeologists generally follow a rule for excavation which says, "Last in, First out!" This means that excavators remove the newest body of soil first, then move on to the next youngest, etc. As each excavator works in their grid unit, they assign a number to each body of sediment-- the level number like those above. Here is the problem- lets say that these two units are nearby or even adjoining each other. You can see that Pete removed the green deposit first, and thus named it level 1. For Pete, the yellow layer is level 2. Megan, on the other hand, hit the yellow layer right away, thus named it level 1. So when they realize they've got the same level, they're stuck with different names for what they believe to be the same thing. That makes life very complicated.

In order to cope with this, the archaeologist begins to interpret everybody's individual strata levels. I'd look at the color, texture, composition, compactedness, and artifact content of Pete's level 2 and Megan's level 1 and say, "Well, these are both 10Y/R 4/4 dark yellow brown loosely packed sandy silt with rich organic duff, 20-40% pea gravel inclusions, and artifacts from the early 20th century. I'm going to argue that these are part of the same deposit- the topsoil, and I will call it Context Unit #1. From then on out, it doesn't matter what unit in which it appears or what "local" level number an excavator gives to it, I can call it CU#1.

The context units often describe periods of time. On our site for example, the clinker layer seems to be a single context unit that (with a little luck, if I'm correct) represents the waste emptied from the kiln's firebox during the very end of Frederick Petersen's career as a potter, during the 1890s. This formed CU#3. The clay layer represents a moment when the Petersen's decided that since Frederick would no longer need to dump the piles of clinker he'd raked from the kiln after each firing, they would cap over that black, pumice-like gravel. They did so with the unused clay aging in Frederick's clay pile, since he would not need it to make pottery. The clay layer became CU#2. Does that sound reasonable? We'll see if the ongoing digging and lab analysis proves that interpretation to be true.

Once you understand the difference between levels and contexts, you'll be able to follow along with us as we produce our site Harris Matrix. The matrix is a way to represent the basic elements of archaeological stratigraphy-- older and younger. Did you ever do a brain teaser that went something like this?

Susan is taller than Ricardo. Ricardo is taller than Eve. Juan is taller than Eve, but shorter than Susan. Tarek is shorter than Susan. Is Susan taller than Eve? Is Juan taller than Ricardo? Is Tarek taller than Eve?

If you can answer these three questions, then you can understand the basic operation of the Harris Matrix. If Cu#3 is under Cu#2 in Grid A, and Cu#2 is under Cu#1 in Grid B, then Cu#1 is older than Cu#3 even though they don't appear in the same grid or seem to touch each other. Get it?

Above, if you assume that the green lens is an ash pile (Feature 1) and the blue deposit is a trash midden (Feature 2), then our matrix would look like this if the context units are as follows: Yellow (I), Brown (II), Red (III), and Purple (IV). Many archaeologists use roman numerals for context units, rather than common Arabic numerals (1, 2, 3,...):

An example matrix using Pete and Megan's sample units from above.

Things are rare, if ever, that simple. But this gives you a good idea of what Chris and I will be putting together over the next week, while the excavation reaches it's mid-point. You'll understand what we mean by level, context, and matrix.

Monday will be a great day! We're going to start excavating the next layer and try to get an idea of what those mysterious aligned rocks are all about. Stay tuned!

July 18th, 2005: Timothy Scarlett

I'm too tired to make an long update today, plus I'm juggling my room arrangements. One note- we did find another fragment of a Petersen-made (?) jar lid pictured above in the first layer. While the lid in level 1 could have been deposited anytime during the 20th century, it could have been made anytime before that. We weren't totally confident Petersen made the lid and decorative motif. This small fragment in an older layer makes me more hopeful. Once we've been able to subject a sample to INAA, we'll be able to measure this with more confidence. This could be the first decorative style we can attribute to Frederick and his family/staff. I hope we find more fragments!

July 19th, 2005: Timothy Scarlett

We've made good progress on our excavation over the past two days. As of this afternoon, we've removed the last of the layer that lay under the clinkers. That deposit had much fewer artifacts in it, so it didn't help us to really bracket the clay layer or the clinker layer yet. Perhaps when we finish the lab analysis of the artifacts, we'll have a better idea. We have a pretty good idea of the Terminus Post Quem (TPQ) dates for the layers overlaying the packed clay. What we can't quite nail down is a Terminus Ante Quem (TAQ) date for the clay and clinker layers. Archaeologists use these Latin phrases to mean "the time after which" (TPQ) and "the time before which" (TAQ), although when speaking we generally use the acronyms only. Just by looking at the artifacts in the screen as I sifted Chris's sediment, for example, I saw plastic candy wrappers and several pennies from the 1960s and 1950s. This means that the sediment deposit in which we found these objects must have been deposited after the 1950s. The vast majority of artifacts in the packed clay and clinker layers have been dietary remains (fish, bird, turtle, and domestic and wild mammal bones) and rusty wrought iron nails. It's good that we've not seen any wire-drawn nails similar to what you would buy at the store today, since we hope the Petersen family deposited these levels between 1890-1870, but none of the artifacts yet provide us with a good, solid, trustworthy date.

Looking down on level 4/5 over entire excavation.

I think that these layers date from between 1870-1898. I reason this because of two things. First Petersen died in 1898 and the clay layer seems to date to just about that time or shortly thereafter in the 1900-1910 period. It could be that when nobody in the family decided to take up Frederick's potting business, they began to clean out the pottery supplies and equipment. Frederick would have kept piles of clay around on the site in various stages of processing. Clay raw from the ground was typically aged for a year in a heap so it could weather and mature. Potters still do this today, by the way, and nobody really knows why it works to improve the clay- it just does. The family might have taken his maturing store of clay after his death and spread it over the coal clinkers in the yard to encapsulate the dust in that layer.

Frederick Petersen likely created the thick layer of coal clinker immediately beneath the clay layer between 1870 and his death (and here I'm still assuming that the clinker was produced as a by-product of kiln firing rather than brought in as fill). Petersen would probably have started using coal after the Utah Central railroad linked to Salt Lake City to the great coal fields of Pennsylvania and the Appalachian mountains (TAQ 1870!). We've taken samples of the coal to see if we can prove that link. I hope my story holds up during the ongoing research! As Sigmund Freud said of psychoanalysis when he made his special guest appearance on Star Trek, "Hey, it was just a theory!"

While I'm on the clinker/coal topic, I'd like to hear if anyone has an idea on something I've observed. When sifting the clinker layer and removing wrought iron nails from the coal-fire waste, I've noticed that most of the wrought iron has small blobs of yellow powder adhered to it. None of the clinker, burned or unburned bone, or any other artifact type has similar blobs of yellow. I've got a theory about the yellow powder, and I'd like to know if anyone thinks this is sound reasoning or way off base. (My peers and students will tell you that I'm always full of theories while we're digging. Some good, some not so good!)

Coal contains sulphur. When burned in an open system, the coal releases sulphur gas and the gas causes all kinds of problems, from acid rain to funny effects on ceramics in a kiln. Some of that sulphur, particularly in poor quality coal, will remain in the clinker waste. When Petersen mucked the clinker out of his kiln and dumped it into the yard, wrought iron nails and objects mixed with it, and it lay underground exposed to oxygen and moisture. Since the nails are highly corroded, the clinker layer was probably also pretty acidic. We'll test soil samples for that back in the lab later in the fall. So I think that some type of electrochemical exchange is drawing sulphur ions through the ground to adhere to the wrought iron. What do you think? Email me your thoughts by clicking here.

We had a visit today from Wilson Martin, Utah's State Historic Preservation Officer (SHPO) and the Associate Director of The Utah State Historical Society. Mr. Martin works with a number of historical, cultural, and preservation groups around the state. He and his staff have worked with me over the years, offering both "moral support" and helping me through the antiquities permit process when needed. I think Wilson had a great time and perhaps we'll see him again before backfilling the excavation units on the 30th!

We'll start on the next layer after our photography/drawing in the early morning. The next layer looks much browner and the surface of the level shows many embedded artifacts, including iron nails, bottle fragments, and more bone. Perhaps we'll finally get some good artifact fragments which will help us figure out where we are in time on the site! The temperature is climbing again after a brief break. We expect several consecutive days of 101-103 degrees F. Brutal. I've moved from the hostel where I was staying to a campground in the Wasatch range. I might not be able to post as often now, but will continue to try and post updates daily. Stay tuned and send me some ideas on my sulphur theory!

Chris takes a break while excavating 0N0W, Level 5.

July 20th, 2005: Timothy Scarlett

Wow! Now we're really learning about the Petersen family and the pottery! I'm pretty sure that the level's were excavating now are from the period 1880-1890. The current level (Level 5 and 6, depending upon the unit) contains lots of artifacts from the pottery and family. We've uncovered several pieces of kiln wasters-- things that came out of the kiln either broken or imperfect. Potters often sold some imperfect ware as seconds, but generally the poorly fired material was smashed in a pile near the kiln. The potter often ground up the broken waster fragments to create grog, a very coarse "sand" that could be mixed with the clay to make saggars and other vessels they could repeatedly subject to extreme heat. Because of the vessels we discovered today, we can start to talk about the style of Frederick and the Petersen family potters- another fragment of the dot-decorated crock lid from above, two undecorated lids, many large fragments of crocks and pans with imperfect glaze on either the interior or exterior, and lots of fragments of the terra cotta roof tiles. Hopefully we will be able to try some refitting study while we're in the field, because we know that many of these fragments do refit. This kind of lab work is perfect for those who love jigsaw puzzles! I'll get some pictures of the artifacts up here soon.

We also discovered some other interesting items while digging. We lifted the rusted bits of a thin sheet of wrought iron to a very surprising find! Neither Chris nor I are experts in zooarchaeology (the analysis of bone and animal parts from archaeological sites). When we started moving the fragments of iron, we saw what we first thought were porcupine quills. We quickly changed our mind after removing more iron and making a detailed examination. We decided that we were looking at bird feathers. See the picture below of the feathers in setu:

Feather shafts still in place during the dig.

You can see the shafts lined up still in the dirt in the lower right. There were also a few shafts that adhered to the bottom of the iron artifact and we had to remove them very carefully to keep them intact. The coolest part is that the feathers have been cut! The cuts start just beneath the base of the feather's shaft (called the calamus) and run along the shaft's entire length. The shaft was then split open and lay flat, then often cut again so that the shaft formed two or even three long spines still attached to the calamus. (Need to know the geography of a feather? Check the great interactive picture here!)

Chris and I spent the morning chatting while digging, trying to come up with all the possible reasons one might cut feathers in such a manner. At first, we talked about why one would want feather shafts cut in such a manner. This was not very productive, since all we could really come up with was some type of quill for writing. The cuts didn't make any sense in that case, since quills are split another way. Then after a bit, it dawned on us that perhaps the person who cut these feathers wasn't after the shaft at all, but rather wanted each feather's vane. We first thought about harvesting feather for down stuffing in quilts and jackets. That made some sense, except that these are the shafts from flight feathers and not down, contour, or even semiplume feathers, the types typically used in down. After briefly considering that perhaps Frederick Petersen was fletching his own arrows, we settled on a much more likely (and interesting) idea. Perhaps the Petersen family, particularly one of the wives or daughters, worked as a plumassier, making feathered arrangements for hats and clothing. Feather trim on hats and clothes were very popular among women of style in the late 19th century and even into the early 20th. The feathers matched with the Asian motifs appropriated by Europeans and Americans during that time. You can see some examples of hats by clicking here. A page from a period text appears here. (This page is in French, if you don't read French, just click on the second image.)

Here is another picture of the feather shafts, after excavation. It allows one to see the split shafts in slightly more detail:

Feather shafts after excavation, including some stuck to rusting sheet of wrought iron.

I'm going to contact some friends that might be able to help me learn more about these. If I hear anything back, I'll post the details.

This morning Kirk Henrichsen stopped by and lent us his digital camera and tripod. You can see the new photos look great and we appreciate his gracious loan! Tomorrow, we'll be working on finishing this level and getting our pictures and drawings done. We hope to dig our way back in time to the 1860s by the end of the week!

July 21th, 2005: Timothy Scarlett (at Lunch!)

We had several visitors from the press today. Watch for us on the news! Some very exciting things today:

1. Dog burial.

2. More pot frags

3. I'm hearing from my peers about the feathers. More later.

4. A strange purple, chalky stuff...

I promised to post some images of the kinds of crocks and pots from which we are finding fragments:

Pot example pot 2

two examples. The first, a storage jar and the other a milk or bread pan. Both of these pots are in the collection of the Brigham City Museum, in Brigham City, Utah. They were probably made at the Pottery Division of the Brigham City Cooperative, perhaps by the master potter there. Ferdinand F. Hansen was also from Denmark and worked alongside Frederick Petersen as an apprentice of Niels Jensen when they all arrived in Salt Lake City in 1852.

Jump ahead to excavation blog week 3.

Jump back to excavation blog week 1.