Throughout the country there are quite a few variations on the four basic types of projects that you are likely to encounter. There are slightly different terms for the various phases of archaeology depending on the state and region you are working in. Generally, the four types of CRM archaeology are: survey, testing, mitigation, and monitoring. I'll discuss them in order since the development of a property will often involve all of these phases in that order.
Survey in some shape or form is usually the first phase of a project. It can be as simple as one person checking likely locations for archaeological sites (reconnaissance survey) and as complicated as a 300 mile 200-m wide corridor stretching across several mountain ranges (linear survey). There is also large block survey where you do long transects from one side to the other, turn around, and come back. In many areas there are very small surveys for cell tower locations or other types of antennas that can be as small as 30-m in diameter or less. There are surveys in many areas of the west that have very specific project area geometry for access roads and pads for geothermal wells and other types of wells (i.e. oil and natural gas). In small areas where a high amount of historical artifacts are expected a metal detecting survey is often performed.
In areas with high amounts of soil deposition survey usually includes shovel testing or some other type of subsurface testing (i.e. post hole or auger testing). A typical shovel testing survey will include transects that are 30-m wide with shovel tests placed 30-m apart. Some states have low, medium, and high probability areas that will change the shovel testing interval depending on the priority. The size of the shovel test also varies by state. In some states the shovel tests are approximately 30-cm in diameter while other states prefer 50-cm square shovel tests. There is a lot of variation.
In places like the Great Basin where there is little to no soil deposition a pedestrian survey is performed. This generally entails a walkover of the area utilizing the 30-m transect interval. Some companies prefer to walkover the entire area prior to recording any sites so they can tell the client what to expect when site recording does begin. Other companies will record sites as they come to them. Like shovel testing, there is a lot of variation.
Occasionally sites will go straight into the excavation or mitigation phase, however, some will go into what's called Phase II in some parts of the southeastern U.S. and simply site testing in other parts. Site testing can include any number of excavation strategies. The chosen strategy depends upon the type of site that is being tested, the depositional context, and the goals of the research design.
There are several possible excavation types that are involved with site testing. The first step is usually some sort of intense sub-surface testing. That could include close interval shovel testing (5-m grid or less sometimes) or auger testing. The results of the close interval investigation can yield information that leads to test pit excavations. These are usually 1 x 1 m test units (they could be larger and trench-like as well). Site testing can also include backhoe trenches and block scrapes (backhoe or shovel) to look at the stratigraphy and to locate features.
If after the previous phases a site is still eligible for listing on the National Register of Historic Places (NRHP) then it will go to the mitigation phase. Mitigation does not always involve excavation. Sometimes the words are used interchangeably. Mitigation refers to the plan that will be used to address the preservation of the site. Preservation could include a reroute of the project area or a fence that would result in completely avoiding the site. It could also include simply paving over a deeply buried site. Data are not lost in that case. The site is simply preserved for a very long time. Often, though, mitigation does involve some sort of large-scale excavation.
Block excavation takes many forms but often has one goal: locate features. Sometimes an excavation will "chase" features by opening units in specific directions based on artifact quantities or some other notable criteria resulting in a crossword puzzle-like shape. Other times a block could be simply a large square or rectangle with 1 x 1 m units systematically excavated. The type of excavation and the depth of the excavation is determined by the type of site that is expected to be there, the types of features expected, and usually by the land form and soil stratigraphy.
The final phase of a project is usually monitoring. Monitoring is often performed by one person that works with the construction crews as they are disturbing the ground. Monitoring is done when sites are expected in an area but weren't found during the other phases. It can also take place when a large site is very near the area being disturbed to ensure that the construction doesn't uncover any additional material or destroy existing parts of the site. When you are monitoring you are on the schedule of the construction company so a lot of waiting is often involved. It's a good time to catch up on your reading.
I could certainly be taken to task for not mentioning terms like "class III" and "inventory" but like I said above, there is a lot of variation in terminology and methodology. It would be beyond the scope of this post to detail the specific terms used in every state and region. It would also be virtually impossible as a lot of states do not have that type of information online and would have to be contacted directly. My hope is that this post gives the novice field tech a brief introduction as to the types of projects they can expect as they travel around our diverse country this summer.
See you in the field!
Written on a winding section of U.S. 50 between Eureka and Ely, Nevada.