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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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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The Hatch Site: Beginnings

Over the next month or so, I'll be sharing some thoughts, images and video from an archaeological excavation here in Central Pennsylvania.  I should state for the record that these observations are mine, and not those of any of the agencies, institutions or other folks involved in the project.  My goal is simply to share a little bit of the past with everyone, and to give readers who don't do what I do for a living an inside view of archaeology.

Here's the basics.

This site is in Centre County, Pennsylvania. It's one of a number of stone tool workshops used for millennia along the banks of a stream.  Just uphill from the site is a source of reddish yellow stone known colloquially as jasper, and to a geologist as goethite. It can be thought of as a kind of flint that is very rich in iron, and it's the iron that produces the ruddy color. It makes fabulous and durable stone tools.  Jasper from this quarry was traded through many parts of the Middle Atlantic region throughout pre-European times.

This site, the James Hatch site, was sealed under soil eroding from nearby hillsides when the land around here was initially cleared in the middle of the 19th century. As a result, it's more or less intact and not much affected by the decades of farming, artifact collecting, and land development that have compromised many other related sites in the area.  It's relatively pristine condition means the site can tell us an awful lot about how the nearby quarry was used, who used it, when they used it, where they came from, and where they went when they left. It's also the sort of site that can serve as a sort of Rosetta Stone for the interpretation of other, nearby related sites that are more disturbed and compromised. You just don't run into sites like this very often.

In the next few months, construction will begin on a bike trail and drainage improvement project that will impact part of this site. Before that happens, an archaeological field school conducted by Juniata College in partnership with PennDOT, the FHWA, College Township, DCNR, and Penn State will be recovering some of the information and artifacts from the affected portion of the site.  The results will include an extensive amount of artifact, soils, and environmental analysis, an immense collection of artifacts, a substantial technical report on the results, a popular-level publication, local exhibits of recovered artifacts, public lectures and presentations, and most importantly, a window into the day-to-day world of the First Pennsylvanians.

The view from that window is, I think, the most significant result.  In my experience, when most folks hear the word "Archaeology", it conjures up  images of pyramids, Roman ruins, even Lost Arks.  I want to help everyone understand something rarely taught in schools and rarely discussed in the popular press: every place has a past, and every past matters. The past is our only available guide for interpreting and preparing for our future. From buried places as diverse and prosaic as the foundations of slave cabins to French and Indian War forts to small Native American encampments, to the ruins of iron furnaces, the stories of other lives and distant times come back to us.  Those stories are by turns instructive, inspiring, sobering, enlightening: we have only to look and listen, and hopefully learn.

A final note. I was involved in some of the identification and evaluation work that located this site.  My field director and I named it for my old teacher, mentor and friend Jim Hatch.  One of Jim's research interests was this complex of jasper quarries and workshops, and he did some of the first and best research on the subject back in the 70's and 80's.  Through Jim I discovered a career, and he also helped me out with a lot of other things as well. If you'd like to know more about him you might give this a read. 

I'll be posting again later this week.

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