Geology & Shovel Testing

 

Geology has always been an important aspect of archaeology, if for no other reason than that we often find artifacts buried in the ground, so we should probably know a little about the ground itself. That seems fairly intuitive to me, but many field techs seem to actively avoid learning about geology and its applications in archaeology. Most field techs find it boring. I once worked with a very intelligent field tech who took a geomorphology class as an undergraduate, but apparently was so bored that she failed to retain any of the information. Let’s be honest—people become archaeologists because they want to find cool things, not because they’re passionate about soils. Kids who dream of becoming Indiana Jones and grow up to enjoy writing anthropology papers are not interested in learning about how dirt moves slowly over time.

But archaeological field technicians desperately need to know more about geology, especially geomorphology. Some might argue that this is a niche specialty that has little to do with the everyday tasks of the average field tech. In fact, there is a disturbing number of young field techs who act as though their job is simply to find artifacts, without a thought for the geological context.

But my decade of experience has taught me that an understanding of geology is directly salient to the routine, everyday duties of the average field tech. If you are a field tech—no matter what anyone else claims—you need at least a basic understanding of geomorphology to carry out your duties correctly. Many field techs are unknowingly carrying out their duties in a very poor fashion.

Let me explain why an understanding of geomorphology is so important. First, you need to understand that one of the most basic duties of a field tech is a task known as “shovel testing.” Archaeological surveys use two main methods: shovel testing and pedestrian survey. Pedestrian survey simply entails that a team of field techs walk across their survey area and look for artifacts on the surface of the ground. This method is only effective in areas where artifacts are visible on the surface, such as in tilled agricultural fields, or arid rangeland where the vegetation is sparse. Meanwhile, some form of subsurface testing is required in areas where artifacts are buried by vegetation, such as grassy pastures or wooded areas where the forest floor is covered by a layer of duff. The most widely used form of subsurface testing is a technique known as “shovel testing” or “shovel probing,” whereby a field tech digs a series of small holes at regular intervals across the survey area, and sifts the excavated soil through hardware cloth in order to locate small artifacts.

That may sound fairly simple, and most of the time it is, but one of the recurring complexities of shovel testing is knowing at which depth to stop digging. Field techs often have trouble estimating how deeply they should penetrate into the ground. The most common advice given to field techs is to stop digging when they reach a “color change” in the soil. This is phenomenally bad advice. Soil profiles can contain multiple zones of differently colored soil, and on some landforms, the artifacts may be hidden in the lower layers. In fact, this advice will ensure that you miss all of the deeply buried sites in your survey area. And these deeply buried sites are likely to be much more intact than anything you will find on the surface or in the plow zone.

So, when should you terminate a shovel test? There is no “one-size-fits-all” answer, because the answer depends on the landform you’re surveying, and every landform is different. This is but one of many reasons why field techs need to learn a little about geomorphology, and geology in general. In fact, I don’t have enough room in this blog post to explain all the ways in which geology is useful to archaeologists.

In the interests of helping field techs learn how to shovel test adequately, I’m going to outline some basic concepts of geomorphology, and try to explain them in a way that makes the information easy to retain.

 

Let’s start with some basic terms:

Geology: the study of the earth (you should know this if you went to college)

Geoarchaeology: the study of geology as it applies to archaeology. Geoarchaeologists study a wide range of topics. They help explain the ways in which various soils form and move around over time, and how those sediments can bury artifacts. They can also locate the geographic sources of the geological materials used to make certain types of artifacts, such as stone tools or clay pottery.

Geophysical archaeology: the study of geophysics and the use of geophysical technology as an aid in archaeological studies. Geophysical archaeologists use magnetometry, GPR (ground-penetrating radar), and electrical resistivity studies to map buried features.

Geomorphology: the study of landforms and how they change over time. Geomorphology does not necessarily have to have anything to do with archaeology—the formation of a mountain range a billion years ago also falls under the purview of geomorphology. Geomorphologists often help archaeologists understand the formation of relatively recent landforms, such as floodplains, loess bluffs, and glacial till fields.

Pedology: the study of soil. It does not necessarily have to have anything to do with archaeology, but it can be applied to archaeology, because artifacts are often found buried in the soil.

Soil horizon: a horizontal band or zone of soil that has a different color or texture than the bands above or below it (or some other distinguishing factor, such as an increase in calcium carbonate or redoximorphic features). These distinctly colored bands usually indicate biological and chemical processes within the soil, such as the downward leaching of minerals. In some very specific cases, these bands may represent the deposition of new layers of sediment. Soil horizons are sometimes also referred to as pedologic horizons or mineral horizons. Archaeologists often mistakenly refer to soil horizons as “strata,” but this is usually not the correct term.

Stratum: a distinct layer of sedimentary rock, such as sandstone or limestone. Archaeologists often use this term (erroneously) to refer to soil horizons, which are horizontal bands within the soil profile. The study of rock strata has little to do with archaeology, but it is useful for geology and paleontology. You could arguably refer to a layer of soil as a "stratum" if it is a discrete deposit that was left at a different period of time than the soil above or below it. But most of the time, soil horizons are imprinted on existing geological material and do not represent discrete deposits, so the term "stratum" would be inaccurate by any standard.

Soil profile: the vertical plane bisecting the soil in any given area, revealing the distinct soil horizons.

Stratified site: an archaeological site in which the artifacts are stratified by time period, with the oldest artifacts in the lowest layers, and the newest artifacts in the upper layers. Most archaeological sites in North America are not stratified.

 

Now that that’s out of the way, let’s talk about the different kinds of landforms you may have to survey.

The most fundamental distinction you have to make, when thinking about soils during an archaeological survey, is between residual soils and depositional soils. A residual soil is a soil that formed in situ from the local bedrock, whereas a depositional soil consists of sediment that has been removed from its original location and deposited elsewhere. This distinction may not seem pertinent to archaeology at first, but I will do my best to explain why it matters. For one thing, sites located in depositional soils have the potential to be stratified or deeply buried, whereas sites located on residual soils have no such potential.

 

Residual Soil

In order to understand the formation of a residual soil, you need to understand what soil is made of. Soil is made of a combination of rock particles and organic material, but it is mostly rock particles. Wherever you are, the soil beneath your feet is probably made of tiny fragments of eroded bedrock.

In a residual soil, the soil particles have not moved away from the place where they once comprised a part of the local bedrock. Imagine you are standing on a slab of bedrock, a million years ago. Now imagine that the rock is being weathered and broken up into tiny particles over time, but these particles remain in roughly the same place. Then, imagine that these particles are being mixed with decomposing organic matter, such as feces and dead plants and animals. This is now a residual soil.

Residual soils are typically found on the ground surface in upland areas where no sediment from other areas has been deposited. For example, the ridges and hilltops of the Appalachian and Ozark Mountains are largely covered in residual soil, mixed with fragments of the original bedrock. Residual soils in such places are often very rocky (soil scientists refer to small slabs of stone in the soil as channers or channery, and large slabs as flagstones). Many field techs who work in these mountains mistakenly assume that the soil they find on the upland ridges has been deposited there, but this is incorrect. The soil most likely formed in situ.

If you dig a shovel test into a residual soil, you may see multiple horizons—or bands of differently colored soil—within the vertical profile. Most archaeologists erroneously assume that these horizontal bands are distinct layers of deposition, with multiple layers of sediment being deposited on top of each other. However, this is not true. There are no layers of deposition in a residual soil profile, because there is no deposition of new sediment at all.

These horizontal bands represent different kinds of biological and chemical change to the original bedrock. The different colors were imprinted on the existing geological material as it was weathered into soil. Let me explain:

The uppermost layer of true soil is known as the A horizon, or “topsoil.” The A horizon has been darkened by the organic material within it, due to its exposure to the biological activity at the surface. In other words, it is dark-colored because the particles have mixed with the decaying organic matter found at the surface.

Below the A horizon is the B horizon, or “subsoil.” The B horizon is also called the zone of illuviation, because it may contain minerals and clay particles that have illuviated (filtered) downwards from the topsoil. In many places, the B horizon has a red or yellow hue, due to the concentration of iron and aluminum oxides that have leached into it from above. The B horizon may also have a higher clay content than the soil above it, as clay particles (the smallest type of soil particle) filter downwards and accumulate in the subsoil.

Below the B horizon is the C horizon, or “parent material.” This is basically broken-up bedrock that has not been affected by the processes I’ve described above. It contains no organic material, unlike the A horizon. And it has not accumulated any downward-moving clay or oxidized minerals, unlike the B horizon.

And below the C horizon is the R horizon, or bedrock.

These are the four basic horizons in a residual soil profile: the A horizon (topsoil), B horizon (subsoil), C horizon (parent material), and R horizon (bedrock).

Some profiles will also contain an E horizon, or “zone of eluviation” (not to be confused with “illuviation”). The E horizon is typically a band of light brown to ashy white soil between the A horizon and B horizon. It contains little or no organic matter, and all of the iron and aluminum oxides have leached away into the B horizon.

In a naturally occurring residual soil, the topsoil may be a very thin layer, if it exists at all—in some places, it may be eroded away before it can form. The act of plowing will modify the A horizon, creating an Ap horizon (plowed topsoil) that is typically about 20-40 cm. thick.

When people drop artifacts on the surface of a residual soil, these artifacts will gradually become buried by biological activity, known as “bioturbation.” Leaf litter will bury artifacts along with various seeds that have fallen to the forest floor. These seeds will sprout roots, and the roots will push artifacts downwards into the soil. Burrowing animals such as ants and earthworms will cover the object with soil displaced from their tunnels. After a matter of decades, an artifact left on the ground in a heavily vegetated environment will be completely buried, swallowed up by the earth.

 

Figure 1. Illustration of residual soil profile

What this means for archaeologists is that sites on residual soils are not chronologically stratified—the older artifacts are not buried deeper than the younger artifacts. Many field techs assume that an artifact found in the B or C horizon must be older than the artifacts found in the A horizon, but this is not necessarily the case, because these horizons are NOT layers of sediment that can be said to be “older” or “younger” than each other. When artifacts are incorporated into the soil through bioturbation, they are mainly concentrated in the A horizon (or Ap horizon), where most of the biological activity is occurring. They may filter down into the B or C horizon as well, but that doesn’t mean that these artifacts are any older than the artifacts above them. Thus, if you find an archaeological site in a residual soil, it is almost certainly non-stratified—it is basically a surface site, where most of the artifacts, regardless of time period, are located at or near the surface.

What does all this mean for the average field tech, who simply wants to know when to stop digging a shovel test? In many cases, if you are shovel testing in a residual soil, it is sufficient to stop digging when you have penetrated 10 cm. into the B horizon. In my experience, most of the artifacts will be located in the A or Ap horizon. These artifacts have been buried by bioturbation, if buried at all, and most of the biological activity occurs in the A horizon, so it stands to reason that the A horizon would contain most of the artifacts.

Some older field techs or crew chiefs may tell you to stop digging when the soil becomes clayey. This can be good advice, but only within certain contexts. It is typically good advice if you are testing in a residual soil, but only if the B horizon contains more clay than the A horizon. As I’ve already explained, the artifacts will probably be located in the A horizon, so you can probably stop when you hit the B horizon. Because clay illuviates downwards into the B horizon, an increase in clay content (in addition to an increasingly red or yellow hue) is a good indicator that you have reached the subsoil.

Many poorly informed field techs have told me that I won't find artifacts in clay at all, but this is simply not true. I have found many artifacts, some very recent in manufacture, buried in solid clay. There is nothing about clay soil that makes it incapable of containing artifacts. If you're testing in a residual soil in which most of the clay has illuviated down into the subsoil, you will probably find most of your artifacts in the topsoil, but this has nothing to do with the clay content of the subsoil. The artifacts will be concentrated in the topsoil simply because the topsoil is close to the surface. In some soils, the topsoil is pure clay, and you can find plenty of artifacts in this clay if you bother to look. I certainly have.

I would also like to point out that artifacts are more likely to move downwards in sandy soil than they are in silt or clay. I have shovel tested in residual soils in which the A horizon and E horizon both consisted of very loose sand (having formed from weathered sandstone), and because the soil was so loose and sandy, the artifacts had all moved downwards out of the A horizon and into the E horizon. So in that sort of situation, it really is useful to keep digging until you hit some kind of clay (which would probably signify the B horizon), even if you have penetrated all the way through the A horizon. You might be finding artifacts up to a meter deep, but from a geological perspective, this is still basically a non-stratified surface site.

 

Depositional Soils

Now that we’ve discussed residual soils, we have to move on to the hard part. Geomorphology becomes much more complicated when soil starts to move away from its original location.

Soil that has moved from its original location and been deposited elsewhere is known as depositional soil. This kind of soil can be transported by many different agents, including wind, water, and ice. Here are a few of the different kinds of depositional sediment:

Alluvial: sediment that has been deposited by running water when a stream overflows its banks and floods the adjacent area. This kind of deposit is also known as an “overbank deposit.” Over time, alluvial sediment accumulates to form landforms known as "floodplains." These landforms are very flat, mostly devoid of large stones, and are found alongside creeks and rivers.

Aeolian: sediment that has been deposited by the wind. Sand dunes are aeolian landforms, which are constantly being shifted by the wind. Loess—or wind-blown silt—is a form of aeolian deposit that can be found on upland areas in many parts of North America, especially on blufftops overlooking major rivers such as the Mississippi, the Illinois, and the Ohio.

Glacial: sediment that has been deposited by a glacier—a moving sheet of ice. Much of North America was once covered in glaciers, and these glaciers left layers of “glacial till” strewn across the landscape. Glacial till can be a combination of many geological materials, including sand, clay, gravel, stones, large boulders, and anything else in the glacier’s path, all mixed haphazardly together. Most of the glaciers of the Pleistocene Epoch have melted, but surviving glaciers can still be found in alpine areas and the far north.

Colluvial: sediment that has been transported downhill by gravitational forces. Sometimes, soil slowly slumps downhill. Other times, it moves rapidly in the form of mudslides or rockslides. Colluvial sediment can be found at the bases of hillsides and mountain slopes.

Fluvial: sediment that accumulates underwater on a riverbed. Fluvial sediment can bury boats or other artifacts left in a river. In all likelihood, you will not need to shovel test in a river or other body of water. In fact, underwater archaeologists have their own methods. Underwater archaeology is not a common part of the CRM industry.

Lacustrine: sediment at the bottom of a lake.

Marine: sediment on the seafloor.

Soil can be transported by more than one agent. For example, during the Pleistocene Epoch, glaciers dragged sediment southwards across much of the Midwest. As the glaciers melted, the meltwaters washed away much of the finely ground glacial silt and clay, transporting this sediment onto the floodplains to the south. These silt and clay particles were then picked up by the wind and carried onto the upland areas south of the glaciers, where they still reside as periglacial loess. If you happen to be walking over a field in Illinois or western Iowa, the soil beneath your feet is probably loess that has been transported by a combination of glacial, alluvial, and aeolian activity.

Now that you have an idea of how soil moves around, I’m going to discuss some of these types of landform in a little more detail, as they pertain to archaeological surveys:

 

Alluvium

Rivers have soil particles suspended in their currents all the time, which is why their water tends to be murky and muddy. When rivers flood their banks, the floodwaters carry these soil particles onto the land adjacent the river. As the rushing water slows down, the particles fall out of suspension and settle on the surface of the ground. This is how floods cause new sediment to be deposited on the floodplains alongside streams and rivers.

 

Figure 2. Flooded agricultural field on alluvial plain alongside Kickapoo Creek, Illinois, after heavy rainfall. The floodwaters deposited fresh alluvial sediment before receding.

Alluvial sediment tends to be “finely sorted,” as particles of different sizes will fall out of suspension at different times, due to their different weights. Thus, sand particles are deposited with other sand particles, silt with silt, and clay with clay.

Most floods are not powerful enough to lift large stones over a river’s banks, which is why floodplains usually do not contain naturally occurring rocks bigger than a piece of gravel. There are some exceptions. For example, the floods within the Columbia Gorge are so intense that they can deposit massive boulders amidst the alluvium. But usually, floodplains are almost devoid of rocks. If you find a rock on a floodplain, there is a good chance it was introduced by humans. Even if it doesn’t look like an artifact, it may be a manuport (something transported by humans). I once found what I initially believed to be ordinary river cobbles in a test unit that I had excavated deep into alluvial sediment, and I made the mistake of thinking nothing of them. But a geomorphologist noticed immediately that they could not have occurred there naturally, and upon further inspection, he revealed to me that these were a type of artifact known as a “pitted stone” (these are often interpreted as nut-cracking stones, but their exact function is not known).

What does all of this mean for archaeologists? For one thing, it means that archaeological sites found on floodplains have the potential to be stratified by time period, with the older artifacts located in the lowest layers of sediment, and the newer artifacts in the highest layers. Rivers are continually flooding and depositing new sediment on their adjacent floodplains, burying old artifacts and creating new surfaces where younger artifacts can be dropped. The Koster site—one of the most significantly stratified sites in North America—is located on (or more accurately, within) a floodplain alongside the Illinois River. Stratified sites such as the Koster site can contain multiple layers of deposits, with artifacts located in each layer, possibly extending several meters underground.

Figure 3. Alluvial soil profile at the Nesquehoning site, a stratified archaeological site in Pennsylvania. Courtesy of Carr and Moeller (2015).

Of course, not all sites found on floodplains are chronologically stratified. Some floodplains do not flood much anymore, and seldom accumulate sediment. I have personally walked over floodplains where artifacts from completely different time periods were all located on the surface together, unburied.

I also need to clarify that the horizontal bands you see in the soil profile of a floodplain are not necessarily distinct layers of sediment. Sometimes they are, and you might even be able to see thin lenses of sand that represent singular flooding episodes. But often, you will see the same kinds of soil horizons that you would expect to find in a residual soil, because the same processes are at work. An A horizon at the top of a floodplain may not necessarily be a younger layer than the B horizon below it; it may just look different because it contains more organic matter, due to its proximity to the surface.

I once surveyed a very old floodplain that was created by a single massive flood at the end of the Pleistocene, and has not accumulated any sediment since, as far as I know. A distinct A horizon and B horizon had formed within the sediment after it was deposited, but the A horizon was not any “younger” than the B horizon—all of the sediment within that landform had been deposited during a single massive event about 11,700 years ago.

What does any of this mean for the average field tech, trying to shovel test on a floodplain? How deep should he or she dig? The truth is that there is no easy answer. You can dig through multiple “color changes” and still find artifacts. You can dig through solid clay and still find artifacts—after all, floodwaters can deposit clay particles in the same way that they deposit sand or silt particles, and these clay particles can bury artifacts too, meaning it's common for sites to be buried under alluvial clay. The advice that is usually given to field techs simply does not apply here (even if the advice would be good in other situations). In some floodplains, you can just about dig forever and still be finding cultural material. Hell, you can dig over a meter into the ground and find only modern plastic, without even approaching the older layers that might contain pre-Columbian artifacts.

I’ve used augers to conduct deep testing in alluvial clay deposits near the Skunk River in Iowa, and found Native American artifacts in thick gley (gray clay) nearly two meters deep. Most field crews would not even try to dig through such thick clay, but if you bother to do so, you might be surprised at what you can find.

One reason that you should not stop digging simply because you’ve encountered a color change is because that color change may indicate the beginning of an Ab horizon (buried topsoil) that is rich in artifacts. Many floodplains contain Ab horizons that are concealed beneath layers of more recent alluvium. These Ab horizons used to be stable ground surfaces, where people may have lived and dropped artifacts. I've seen too many field techs penetrate into an Ab horizon during a shovel test, only to stop digging, mistakenly assuming that the Ab horizon was subsoil.

I once surveyed a floodplain in Oklahoma, which contained a layer of dark, rich, heavily organic soil about 90 cm. below the surface. It was covered in a mantle of light brown alluvial sediment. The organic layer was clearly an Ab horizon, and it contained several artifacts and burnt animal bones, which revealed the presence of a significant pre-Columbian site. The only reason I mention this site is because the floodplain where it is located had been previously surveyed, but the original crew had not found anything. There could have been a lot of reasons for their failure to locate the site. They may have assumed that the Ab horizon was subsoil, and stopped digging when they found it. Most of the artifacts were about a meter below the surface, and the original crew was probably not required to test that deeply anyway. In addition, the ground may have been so hard at the time that they could not dig at all—some parts of the Southern Plains become as unyielding as concrete when the ground dries out in late summer. I once tried to survey another floodplain in Oklahoma where it was virtually impossible to shovel test because the earth was simply too hard and dry at that time of year, and I still wonder what might be buried there. 

My point is that it is very easy to miss sites that are contained within a deeply buried Ab horizon in an alluvial plain. When encountering a floodplain, you may need to adjust your methods and test more deeply than you otherwise would. Perhaps use an auger to penetrate farther into the ground than you can with a shovel. At the very least, you need to know not to stop digging if you reach an Ab horizon, because it is not "subsoil."

 

Figure 4. Illustration of alluvial soil profile with Ab horizon

It is also worth noting that the floodplain I discussed above was covered by a tilled agricultural field where the ground surface was completely visible, but there were no artifacts on the surface. They were all too deeply buried, about a meter below the ground. Many crews would have felt it sufficient to conduct a pedestrian survey here, without shovel testing at all, but if my crew had not implemented shovel testing, we never would have found the site. This is one of the complexities of trying to survey a floodplain. The ground surface may be bare enough to allow for pedestrian survey, but if all the artifacts are buried under alluvial sediment, pedestrian survey will not be effective, and you may need to resort to deep testing with a shovel or auger.

This is a case study in the importance of knowing how to read the earth. You should know when you’re standing on a floodplain, and if you are, you should be willing to dig deep, in case there are deeply buried artifacts. You should be willing to shovel test even if you have perfect visibility for pedestrian survey. While you’re shovel testing, you should know an Ab horizon when you see it, rather than mistaking it for subsoil, and you should understand that even if you encounter a B horizon (subsoil), there may be an Ab horizon below it. And you should know that just because the soil is clayey and difficult to dig through, or dry and compact, does not mean it is culturally sterile (devoid of artifacts). Floodplains make life more complicated for field crews, and unfortunately, many field crews are behind the learning curve, and probably end up missing archaeological sites.

 

Glacial Till

Layers of glacial till cover much of the ground surface across the Midwest and New England. Glacial till can contain everything from clay to sand to gravel to boulders.

These deposits were left during the Pleistocene, and since that time, many of these upland deposits have not accumulated any new sediment. Some of the upland glacial till deposits in Illinois have been buried under layers of loess, but in many other places (such as Ohio), the glacial till deposits are directly on the surface. Over the past 11,700 years, soil horizons have been forming within the glacial till after it was deposited, in the same way that similar horizons form within residual soils. The soil at the top accumulates organic matter, and the soil below it accumulates clay and iron oxide, causing visible horizontal bands to form. The topsoil is not necessarily more recent than the subsoil.

Artifacts left on the ground surface over the past 11,700 years will be concentrated at or near the surface. Most artifacts will be located in the A horizon. If you are shovel testing through glacial till, it is usually safe to terminate your test at the B horizon.

 

Periglacial Loess

I discussed earlier how silt and clay were washed out of melting glaciers, and then picked up by the wind and deposited on upland landforms as loess (wind-blown silt). Because these loess formations are affiliated with glacial activity, most of them stopped accumulating sediment after the Pleistocene. Artifacts made in the past 11,700 years will be on the surface, or in the topsoil.

There are some loess hills along the Missouri River that have probably continued to accumulate sediment into the early Holocene. In places such as these, very old artifacts (such as Paleoindian artifacts) could possibly be deeply buried, much as they would be in floodplains.

 

Other Landforms

Geomorphology is too complicated for all the salient information to be mentioned here, but there is a wide array of landforms you may have to survey over the course of a career in CRM. There are shifting sand dunes in southern Colorado, which can continually bury and then re-expose ancient artifacts. There are ancient Pleistocene lakebeds in northern Nevada, which have since turned to desert, and now have artifacts lying directly on the surface amidst the sagebrush. The coastal plain along the Gulf Coast contains sandy deposits that originally formed under the sea. In the badlands of North and South Dakota, ancient deposits of volcanic ash have transformed into slopes of bentonite clay.

 

Figure 5. Ancient Pleistocene lakebed in northern Nevada. What was once lacustrine sediment is now the surface of a desert, sparsely covered in sagebrush.

As a general rule, you will not need to shovel test much in the Western states, because the Western climate is dry, and artifacts can be visible through the sparse grass or sagebrush. Shovel testing is mainly implemented east of the Rocky Mountains. But even in the West, it can be useful to have some basic knowledge of geomorphology.

I haven’t even discussed the myriad of other ways in which geology can be applied to archaeology. Archaeologists can identify the geological material from which a stone tool was made, and trace it to a geographic area where that material naturally occurs. They can use pXRF analysis or neutron activation analysis to determine whether a sherd of pottery was made from local clay. They can even use a magnetometer to detect the buried remains of cooking pits or burned houses. But all of that falls outside the ordinary duties of the average field tech. The purpose of this blog post is simply to help field techs become more adept at the otherwise very simple task of shovel testing. The fact that such a long post can be written about this topic, while only offering the most simplified version of the geological sciences, should be a testament to the fact that a field tech’s job is more complicated than most people in CRM (especially field techs) are willing to admit.

 

 

Sources

 

Alex, Lynn M. 2000 Iowa’s Archaeological Past. University of Iowa Press, Iowa City.

Balek, Cynthia 2002  Buried Artifacts in Stable Upland Sites and the Role of Bioturbation: A Review. Geoarchaeology: An International Journal 17(1):41-51.

Butzer, Karl W. 1978 Changing Holocene Environments at the Koster Site: A Geo-Archaeological Perspective. American Antiquity 43(3):408-413.

 

Carr, Kurt W. and Roger W. Moeller 2015 First Pennsylvanians: The Archaeology of Native Americans in Pennsylvania. Pennsylvania Historical and Museum Commission, Harrisburg.

Luhr, James F. 2003 Earth. DK Publishing, New York.

 

Schaetzl, Randall J. and Michael L. Thompson 2015 Soils: Genesis and Geomorphology. Cambridge University Press, New York.

 

Schwegman, John E. 2016 The Natural Heritage of Illinois: Essays on its Land, Waters, Flora, and Fauna. Southern Illinois University Press, Carbondale.

Stein, Julie K. and William R. Farrand 2001 Sediments in Archaeological Context. University of Utah Press, Salt Lake City.

Targulian, V.O. and R.W. Arnold 2008 Pedosphere. In Global Ecology, edited by Sven Erik Jorgensen. Academic Press, Amsterdam.

Waters, Michael R. 1992 Geoarchaeology. A North American Perspective. University of Arizona Press, Tuscon.

Updated April 11, 2024