Archaeology: Survey and Excavation

Before stepping outside to begin fieldwork, what must the archaeologist do? Crucial issues, as first step such as gaining permission or access to lands, permits for work on public lands, and making sure you have laboratory and storage space for processing and curating the materials you might dig up. Another essential step is connection with the local people, landowners or other residents, to find out what they might already know about the land. Have they collected artifacts, seen darker soils when plowing, or heard that some older residents once knew about older historic structures that once stood there? What will be the effects of your digging or surveying upon the local community? In our new era of mistrust of science and government, I have had to assure people that finding artifacts on their land will NOT mean that the state takes it away from them, and that I would like to see the artifacts they have collected ONLY to photograph them, if permitted, not to take them away.

What is meant by archaeological survey? This is the answer to the common question, “how do you know where to dig?” (And again, we do not want to dig everything we find, but preserve as much as possible.) Survey is the process of locating the archaeological resources in a given area of land. Doing the background work can help pinpoint areas of greater interest. Besides the practical considerations mentioned above, research on the archaeology of the region is also absolutely essential. Where are most prehistoric sites located? Along coasts or rivers or springs? Those portions of land would then have the highest probability and perhaps require the greatest scrutiny. Is the survey being done in the path of proposed construction? If so, then perhaps only the areas where the ground will be disturbed need to be examined.

Learning the environmental and historical variables must take place before you step into the field. Your book describes the work of Heinrich Schliemann, who read the classics and located the Troy of the Trojan Wars. It also mentions the importance of good maps, not only modern, but historical, to show both how the landscape may have changed and what historic remains might have once been located there. In more populated urban areas the old Sanborn insurance company maps may show building outlines or “footprints” that lie underneath modern features.

What is remote sensing? Anything (usually technological device) that helps you learn what is on/in the ground without your having to be there or dig there. So a map is a remote sensing device, but even more sophisticated are aerial photos, including aerial infrared photos, satellite images, and pictures generated by various geophysical prospecting techniques such as magnetometers, electrical resistivity detectors, ground-penetrating radar (GPR), other kinds of radar, sonar, and all those spy devices developed by your friendly military scientists. The raised fields of the ancient Maya were not apparent on the ground in Central America, because, well, it is a jungle out there, but they were easily seen during testing of military imaging technology in the 1970s. Buried or jungle-shrouded features can be anything from just black midden stains to traces of ancient canals, buildings, mounds, and other earthworks. If you do as much remote sensing as possible before and during the on-the-ground fieldwork, site discovery is greatly enhanced.

How is archaeological field survey conducted? There is no substitute for being there and walking around. Especially important is covering open and disturbed ground, where shallower remains may have been churned up by plows, other heavy road building equipment, burrowing animals, and so on. In Florida, we walk dirt roads, plowed lanes in orange groves and cotton or soybean fields, and look for gopher tortoise burrows where the dirt is thrown out around the entrance and may have artifacts in it. We see on the map where the streams and springs are, and the highest ground nearby, and usually find prehistoric sites there. At the northeast end of our campus is a ditch along the road filled with slimy water and alligators today. Old maps show it was a pond with a stream outlet to Cypress Creek and the Hillsborough River, major transportation and communication routes in prehistory. It is no surprise that there are prehistoric human habitation sites around this last remaining small ditch! We have also talked with old-timers in the grounds department and elsewhere, who remember finding “arrowheads” (spear points) in that area of campus, especially during construction of various buildings there.

Does survey include digging? Subsurface sampling is enormously important, especially in the eastern U.S., which is often heavily forested. In the desert Southwest you can drive around and see the standing ruins of prehistoric pueblos. Many of these “windshield surveys” used to be done in the East, as well, by archaeologists looking for sites in plowed fields. But there is no substitute for seeing what is buried, whether there is cultural material on the surface or not. Methods of subsurface investigation during survey must be fast but careful. The shovel test is usually 50 cm square and a meter deep according to Florida state guidelines; it is easily dug in our soft sands, and the soils can be dry-screened by one fieldworker while the other is digging (show photos of shovel-testing and other methods). We can also take cores or soil probes, pressing or twisting a tubular device into the ground to see what comes out. Besides 1-inch and 4-inch diameter hand-coring tools, we have a gas-powered auger which drills into the ground, which can be even faster but more destructive.

What other technological devices must modern archaeologists use? Lately we must have a Global Positioning System (GPS) unit, which reads signals bouncing off several satellites to give exact locations in latitude/longitude or other coordinates. We also want to utilize Geographic Information Systems (GIS), which are simply computerized ways of making maps of different features that can be overlain to show relationships of natural and cultural features through time.

Once the site is found, how do you know what part of it to dig? Site survey and mapping can be done at several levels, from a rough sketch using a compass and pacing distances to formal mapping with a surveyor’s transit, electronic station, or other device. A typical local site here is a scatter of artifacts on the surface, but there may be a mound, concentrations of artifacts, a stream or hill, modern features such as roads, that all need to go on a base map. We often set up a site grid in uniformly sized squares so that everything can be precisely mapped in plan view and later in three dimensions. There are good examples in your book (pp. 91-93; show other examples of site maps).

After getting control of horizontal space, how does archaeology tackle vertical space? Excavation must be done with an understanding of stratigraphy, the stratification or vertical positioning of soils and other materials in layers or strata. The law of superposition dictates that the earliest strata are usually the deepest (but there are exceptions in disturbed strata such as riverbank flood deposits or deliberately constructed mounds—see diagrams in book, pp. 96-97). It is important to be able to recognize strata deposited by natural geological processes and cultural processes or both, but it may be difficult. Since we want vertical as well as horizontal control, we ideally want to excavate one stratum at a time without mixing them. This is not always possible if color, texture, and content differences are hard to see. In such cases we can still maintain some control by digging in arbitrary levels of a standard thickness, such as 10 cm at a time. Sometimes we might dig in smaller arbitrary levels of 5 cm within a thicker cultural stratum, for even tighter control. Or, for a really slow but careful dig, recording each and every find in three dimensions can be done too. A formal excavation unit can be as small as a meter square or as large as many meters. We usually dig in squares to be able to see a clean view of vertical layering. We usually use metrics since they are easier and more international, though some historic archaeologists may dig in units of feet and yards if the site is, say, a British fort that was laid out using those kinds of measurements.

What is soil flotation? Just a fancier way of recovering the smallest remains, it involves taking a standard-sized soil sample (we use 9 liters) and processing it not through the regular screen but through the flotation machine. This is a device, usually homemade, with a 50-gallon drum, a hose connected to a showerhead inside, and graduated screens within, as well as a very fine screen to catch bits of charcoal and other light materials that float to the top and out a spout. Much good information on food remains has come from soil flotation, which can recover seeds, fish scales, and other tiny remains lost to archaeologists in the past. A late prehistoric site we excavated in northwest Florida was transformed into a historic site when a tiny glass seed bead was recovered during flotation!

What methods are used in recording information from field survey and excavation? A plethora of field forms (show examples), field notes in waterproof ink on surveyors’ waterproof notepaper, photographs, maps, drawings, and other techniques are used. This may also include audiotaping and videotaping fieldwork. There can never be enough recording, and it is often very redundant. But since information is lost the minute things come out of the ground, it is crucial.

How much survey and excavation is enough? It depends upon the individual project. There is a big difference between a multiyear research project at a protected site and a salvage project where survey and excavation must take place in the path of proposed construction. American archaeologists, especially those working in cultural resources management, differentiate among the levels of investigation as follows: Reconnaissance survey usually involves walking around the project area looking for surface materials and doing the historical background work to see what might have been there and what is already known or found. Phase I survey is more intensive and involves subsurface methods such as shovel testing and writing a more comprehensive report. Phase II test excavation may be done after survey has identified the sites in an area, to place formal test units at those sites suggested to be significant. Significance is often difficult to define. It can be understood in local to international terms. A significant site will have undisturbed cultural deposits that have good potential to produce new information about a past people. This usually includes features, good intact midden soils, diagnostic artifacts, and so on. An internationally significant site will usually be a major monument. Phase II excavation can even include stripping off disturbed soils with heavy equipment such as a front end-loader to see if undisturbed features such as refuse pits or house patterns are present below.

Phase III excavations, also known as salvage or data recovery, might take place at the sites determined during Phase II to be significant but destined to be destroyed by whatever construction is planned. During Phase III more extensive excavation units are dug and as much information and material as possible is recovered, since this will be all that is retrieved from the site (usually) before it is gone. There is obviously the ethical consideration, again, of digging and thus destroying too much of a site if it is NOT destined to be disturbed or destroyed. Furthermore, it is always better to conserve instead of dig. Good cultural resources management strategies often involve working with those planning the construction to avoid site destruction. For example, after surveying and Phase II testing in the path of a housing development in Florida, we might find a few sites that are significant. We might persuade the developer to move planned buildings away from the site, change the design of the entire plan, or dump some loads of fill dirt over the site and preserve it as a park or green space, maybe even with an outdoor display describing the prehistoric people who once lived here (good public relations for the developer, as well!).

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