Wednesday, June 7, 2017

The Hatch Site: Adventures in Flintknapping

Almost two weeks ago, the students in the Hatch Site field school had the misfortune to witness the art of the flintknapper as demonstrated by yours truly; possibly the world’s worst practitioner. This came about due to a schedule conflict for Susanne Haney, my colleague and friend in Indiana Pa, who is a real flintknapper. That said, I do know more about it than the students, and I’m an accomplished talker (some would say BS artist), and since I got through it without smashing a finger or cutting my hand or otherwise making a spectacle of myself, I managed to carry it off nicely.

For those of you who are unfamiliar with the craft, a flintknapper is a producer of chipped stone tools. By carefully removing sharp flakes from a piece of suitable raw material via percussion with harder rocks (aka hammerstones) or with softer hammers such as antler, bone or even hardwood batons, a chunk of flint or jasper can gradually be reduced in size (or thinned) and shaped into a variety of sharp and durable tools and weapons. The resulting tools can be chipped on both sides (bifaces) or on just a single side (unifaces) depending on the kind of tool the flintknapper has in mind. These tools are really the points or bits in compound tools and weapons with handles or shafts made of wood, cane, or bone and bound with sinew or leather, and glued with pitch. After centuries, only the stone components survive, and that’s frequently all an archaeologist has to work with in the careful reconstruction of the past. Incidentally, thats where the term “stone age” comes from: a misleading name for what might have easily been termed the wood, bone or leather age. While stone tools are just a single component of a complex and functional prehistoric technology, through careful study and experimental archaeology, they can tell you a lot about the people who made and used them.

At manufacturing sites like the Hatch Site, and indeed at most stone age sites, the overwhelming majority of artifacts are termed flakes or sometimes, debitage (a French term: many pioneering archaeologists in the 20th century were French). A good analog might be the workshop floor of a woodcarver. There are no finished carvings to be found there, but many, many shavings. While the ubiquitous debitage doesn’t seem particularly impressive, close study reveals much about how it came to be.

Modern flintknappers have reconstructed the prehistoric techniques and processes. This begins with the removal of the outer rind from a rough nodule of material, to reveal the smooth and glassy interior. This work is done with a large and heavy hammerstone, and is called primary reduction. The results are large flakes (usually bigger than an inch or more) with cortex (the outer rind of the nodule) visible, and the roughly prepared piece of raw material, called a core. The flintknapper then switches to smaller hammerstones and batons, and begins to methodically reduce the core. This involves preparing the edges of the core to allow for the efficient and successful removal of material (aka setting up a platform) and then carefully striking flakes off the core. The result are somewhat smaller flakes with no visible cortex, and often with small remnants of the platform still visible at the precise spot where the blow fell. These are middle stage or secondary stage flakes, and the larger examples can become tools themselves. The core and the larger flakes are then further reduced and thinned with smaller and lighter hammers producing smaller and thinner debitage as the bifaces are brought to an oval shape (a blank). These blanks are then either taken away for trade or stored for later final reduction, or they are immediately reduced to finished tools. Final sharpening is actually accomplished with the tip of an antler tine or sharp bone and simple pressure. Pressure flaking, i.e. pushing small flakes of the edges of a nearly finished tool, produces a durable and sharp serrated edge, and very tiny flakes (1/8 inch or smaller). These small flakes resulting from final shaping and then sharpening are final stage or tertiary debitage.

It’s worth noting that at this point in the excavation, it appears that the bulk of the artifacts being recovered at the Hatch Site are middle stage biface thinning flakes. The picture that is starting to emerge is of a workshop dedicated to the production of thinned blanks rather than the final production of tools or the initial roughing out of larger chunks of raw material. We will see if final analysis of the artifacts supports this impression or not.

Another obvious feature of many of the Hatch Site flakes is their red color. This is a result of the intentional exposure of the jasper to heat. Heat treating tempers the material, increasing its durability and making it behave more predictably during the reduction process. As part of my foray into the world of the flintknapper, I decided to conduct an experiment in heat treatment.

As part of my research into the proper method, I was first instructed in how NOT to do it. A colleague explained that his first attempt was at a camping outing with family and friends. This outing may have involved the consumption of a moderate amount of strong drink. Just before retiring to his tent for the night my colleague remembered he had a good sized chunk of jasper in the back of his truck, and thought he might make good use of the remains of the evening campfire to heat treat it. Without a second thought, he tossed the nodule into the hot coals, and then went to brush his teeth.

Now it happens that jasper nodules often contain fine cracks just like the sedimentary rocks they form in, and it also happens that these cracks may contain some water. Heat, of course, converts water to steam, and steam expands rapidly in a tight or closed space.

Soon there was a terrific report, and the air was suddenly filled with jasper shrapnel and flaming coals, along with shrieks, swearing and the barking of dogs! Mercifully, no one was injured, but it produced a good deal of excitement in the campground, and was also a very teachable moment.

Armed with this knowledge, I took a palm sized bifacial jasper core I somehow succeeded in producing, and packed it in sand inside a coffee can. I placed the coffee can into the bed of coals in my charcoal grill in the evening, and the next morning I found the brownish-yellow core was now a uniform brick red. I have yet to attempt further reduction, but I’ll do so soon, and report back on the results.

A final note on flintknapping. In any and every Stone Age settlement and encampment, while all the residents undoubtedly understood flintknapping, there were certainly experts. It’s very likely that these experts were able to barter their expertise to their friends, neighbors and kin in exchange for food, clothing and other good and useful things. Flintknappers were very likely among the very first entrepreneurs and part or full-time professionals. They were the vanguard of a cultural evolution that gave us a world of auto mechanics, software designers, football coaches, chefs, EMT’s, office administrators, and yes, archaeologists. They were among our first toddling steps toward a modern economic system dominated by specialists and by trade. The archaeologist’s window into the past doesn’t just allow us to look in on our predecessors, but also to peer at our own reflection. Actually, it’s not a window, it’s a mirror.

Sunday, June 4, 2017

The Hatch Site: Halfway There

Friday, June 2nd was the halfway point in the Juniata College excavations at the Hatch site. A lot has been accomplished and learned.

To date, the students and staff have moved all the 19th and 20th century colluvium off two 10-meter square excavation blocks, and excavated through the buried A horizon in the central areas of both blocks. The underlying B horizon has been carefully cleaned and prepared for final photographs and mapping prior to continuing excavations into the underlying deposits.

As expected, thousands of pieces of jasper have been recovered. Less expected were smaller, but consistent amounts of a black colored chert (again a type of flint). There’s good evidence that the chert is encountered only in specific parts of the excavation block. This in turn means that the horizontal distribution of artifacts isn’t random. We will very likely be able to tease apart both task-specific and possibly time-specific episodes of occupation and use at the site.

We also have exciting news on the time front. Normally, you don’t find many complete projectile points (the business ends of spears, darts and arrows) at quarry workshop sites like the Hatch site. Sites like this are the result of manufacturing new tools, tools that the former occupants normally took with them when they left the site. Since projectile points were made in very specific shapes and sizes at very specific times, their scarcity can make it really tough to provide good dates for the occupations at such sites. During our earlier excavations here in 2015, we recovered a single, partially completed point or pre-form, that appears to date to Transitional Archaic times, some 4,000 years ago.

In the course of the current excavations, we’ve added a notched point and a stemmed point, both of which are likely Late Archaic forms that are closer to 6,000 years old.

On Friday, right at the bottom of the A horizon, another pre-form was unearthed with a distinctive deep notch on its base. Such points are called bifurcates and they date exclusively from the end of the Early Archaic period some 8,000 years ago.

In addition to the points, a small fire reddened area with charcoal and jasper flakes is emerging from the top of the B horizon.  This may be a location where jasper was heat-treated to improve it's durability and predictability as a raw material.  If the feature pans out, the charcoal will allow a radiocarbon assay that will further help us date some of the site occupations.

The picture that’s emerging is one of regular visits to this place over not centuries but millennia. These visits appear to have all been focused on the manufacture of tools rather than on more generalized day-to-day activities like food preparation. There seems to be a long-lived tradition of site use that spans thousands of years and many groups of people. While it’s very likely that each individual visit might have been a fairly short-term affair involving only a few people, when you multiply such visits across hundreds and thousands of years, you wind up with a landscape covered with the remains of tool manufacture, not unlike a factory floor. Indeed, that’s sort of what the site is!

Another important development this week did not directly involve the archaeology of the site, but instead the site’s namesake. Diane Hatch, Jim’s wife, stopped by to visit, and brought her daughter and grandkids! I was not on-site and missed them, but I hope they come back. I think the sight of all the students hustling around a busy archaeological excavation, and his own family, especially his grandkids, having a chance to check it all out, would have had Jim grinning from ear to ear.

We’ll be exploring the process of stone tool manufacture in more detail in a future entry, which will feature the world’s worst flintknapper…

Until then…

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Sunday, May 28, 2017

The Hatch Site: Why It's Here; Of Landforms, Soils and Sites

The Hatch Site is one of a complex of stone tool workshops all focused on the use of the Jasper quarries up the valley.  What makes it unique and important is a happy accident of topography.

The site sits in a small, bowl-shaped area at the foot of some steep slopes that lead up-valley.  These surrounding slopes are ultimately, the reason the site is so well preserved.  To understand that point, it's necessary to first grasp exactly where what we call soil (and what a geomorphologist calls sediment) comes from. Once you understand how soils form, you can begin to understand how the archaeological sites within them form as well.

Of course, ultimately ALL soil comes from interactions of weather, gravity and bedrock geology.  But that interaction can happen in many different ways.  In the vicinity of the Hatch Site, there are three basic types of soil formation going on.

On the relatively level uplands west of the site, soil is forming in place as a residue of the slow weathering and decomposition of the underlying limestone.  This residue is called, unsurprisingly, residuum.  It's not usually very deep, and consists of a dark, organically enriched surface layer (the topsoil or A Horizon), a lighter colored clay or silt layer beneath the topsoil (the B horizon), and often coarse, stony, and even lighter colored material decaying from the bedrock (the "parent material" or C horizon). In residuum, artifacts and site features are only found in the topsoil (which in Pennsylvania, an agricultural breadbasket for over two centuries, is almost always plowed) and on the very top of the underlying B horizon.

Water, wind and gravity are always removing material from the surface of the A horizon, even as the underlying B horizon becomes enriched with organic material via the actions of roots, earthworms, and other animals and insects, and creates new A horizon from beneath.  The material eroded from residuum creates new kinds of soils, called depositional soils. One of the ways that happens is via transport by gravity down hill on slopes.  This produces deep soil deposits at the base of the slopes called colluvium.

Another kind of depositional soil is produced when sediment is picked up, carried and deposited by streams.  The banks of streams are often mantled with silt and sand left behind by floods.  These level, stream-side areas are called floodplains and the soils that comprise them are alluvium

Both colluvium and alluvium have the potential to bury archaeological sites, sometimes to surprising depths.  As colluvial and alluvial deposition continue over centuries and millennia, they can also preserve superimposed layers of artifacts and features from successively older and deeper human occupations. These are called stratified sites, and they are the most valuable kinds of archaeological sites.

The goal of archaeology is the detailed reconstruction of human behavior from the objects and features left behind by our predecessors. Stratified sites make it relatively easy to tease apart the evidence from specific occupations, because they're separated from each other like layers of icing in a layer cake.

At the Hatch Site, a thick layer of colluvium eroded from the surrounding hill slopes when the little valley was first logged and farmed in the mid-19th century. This colluvium has buried and sealed an old topsoil or A horizon, that was plowed, but only during the 19th century. That A horizon contains thousands of jasper flakes, tools, and other detritus that documents the stone tool production process.  Beneath the A horizon is a B horizon that appears to be alluvial, and contains artifacts deposits in sediments that that have not been plowed.  The site has the potential to produce some very fine-grained pictures of day-to-day life at this stone tool workshop as it was used repeatedly for centuries.  Thanks to the cap of colluvium at its surface, you would never even know the site is there!

A note: The first week of excavations was completed at the site yesterday.  In the next installment I'll report on their progress so far, and I'll try to describe what we've learned about the process of making stone tools from modern experimental archaeology.

The Hatch Site: Beginnings

The Hatch Site: Underpinnings

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Tuesday, May 23, 2017

The Hatch Site: Underpinnings

Much, maybe most, human land use is ultimately a product of geology. Bedrock and the soils and land forms (e.g. floodplains, glacial terraces, etc.) that form on the bedrock often define where and how we live, and that’s always been true. At the Hatch site, geology largely explains the local landscape, and why the site is there.

The bike trail project area is situated in the Nittany Valley whose bedrock geology consists primarily of sedimentary rock of Ordovician (ca. 450 million years old) and Cambrian (ca. 530 million years old) age. The rock is of marine (oceanic) origin, and many of the formations are composed of the remains of various kinds of shellfish (limestones and dolomites) or of sands and gravels (sandstones, quartzites, and conglomorates). The bike trail project area sits atop two Ordovician formations: the Nittany (primarily dolomite) and the Axeman (primarily limestone). There are several SE to NW oriented faults located beneath and near the project area and the site. Faults are cracks in the sedimentary rock produced by movement of the earth’s crust and deep subterranean pressure. The project area is situated along the edge of a northwest to southeast trending narrow valley. This valley is likely a graben, a geologic term for a valley formed by a pair of parallel faults that produce a subsidence in the bedrock.

This geology has direct and very significant implications for the interpretation of the Hatch site. Without a doubt, the most significant of those implications is the association of the local geologic formations with a mineral known to geologists as goethite. Goethite is formed as hot subterranean water containing dissolved silica infiltrates iron rich formations such as the limestones and dolomites found in the Nittany Valley, through geologic faults. The nodules that precipitate from this hydrothermal reaction are a hydroxide of iron. The nodules that are richest in iron are known as bog iron, a type of iron ore. Goethite ores were used extensively in the 19th century iron industry that flourished in and near modern State College. The nodules that are richest in silica are jasper.

In this part of the Spring Creek Valley, those nodules appear as yellowish chunks of often smooth, even glassy material. The First Pennsylvanians discovered these jasper nodules at least 12,000 years ago, and exploited them until the arrival of the Europeans. The quarries where the nodules were mined from the soil are about a half mile away from the Hatch site, at the other end of the graben valley. The Hatch site is on relatively flat, well drained ground close to a tributary of Spring Creek, an ideal place to encamp and begin the process of converting chunks of jasper into tools.

At the Hatch site, understanding the geology helps us understand the site. While we rarely think about it, local and regional geology plays an equally important role in understanding our own communities today. Many towns and cities in northeastern and southwestern Pennsylvania exist because of their proximity to the roughly 300-million-year-old Pennsylvanian Epoch Anthracite and Bituminous coal deposits of the Middle Atlantic Appalachians. Limestone valleys (karst topography to a geologist) like the Nittany and Cumberland valleys have stable, valuable and reliable streams and very rich high PH soils that produced important agricultural market towns like Bellefonte and Carlisle. Iron-rich sedimentary and metamorphic rock and limestone and dolomite formations produced Pennsylvania’s innumerable 18th, 19th and 20th century iron furnaces and foundries, and the hundreds of communities large and small that grew up around them.

How we use and occupy the land here in Pennsylvania is largely a product of what lies beneath that land: the complicated and durable Appalachian geology beneath our feet. As the former residents of the Hatch site are teaching us, that’s been true for a very long time.

The Hatch Site: Beginnings

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