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Los Angeles Times Article on Solar Energy Development in the Mohave Desert

I suggest folks read this article with objectivity because it reads like a one-sided a hit piece. Did the reporter bother to contact the archaeologist(s) responsible for the work? Does anyone have the slightest idea of the circumstances surrounding the work contract? Archaeology of this nature is performed under legal contract. BLM is required to comply with Section 106 of the National Historic Preservation Act, the American Indian Religious Freedom Act, the Native American Graves Repatriation Act, the Antiquities Act, and the Archaeological Resources Protection Act. Southern California Edison (SCE) may be required to comply with State laws relating to their roll as a public utility including but not limited to the Public Resources and Administrative codes. Legally, if the project was entirely on BLM land, SCE is required to follow the stipulations of their BLM permit and applicable State regulations that relate to their roll as a public utility. The consulting archaeologist–presuming there was one–would be contracted to develop a scope of work in concert with BLM and SCE technical staff. If BLM worked with SCE to skirt laws, the consulting archaeologist is left with no pleasant options: S/he can quit the project (possibly their job) and see it go to a competitor with more open-minded sense of ethics or s/he can state in writing their belief that BLM/SCE isn’t complying with law, point out that ultimately SCE may be required to comply retroactively, and then agree to work within parameters defined by the responsible agency(s). In the world of contracting, most contractors would elect the second choice: that is, present due diligence to the client and compliance with the responsible agency-defined scope. This sort of situation occurs almost every day somewhere in the US and it places a burden on the consulting archaeologist that shouldn’t be underestimated. I know dozens of consulting archaeologists and not one wakes up in the morning thinking, ‘Hmmm, I think I’ll skirt the law today so my client can save a few hundred grand.’ They may wake up asking themselves can how the can comply with the law cost effectively and ethically responsible fashion, while limiting their client’s exposure to the sort of fallout described in this letter. I can’t begin to count the number of times that I’ve read/reread applicable laws and associated case law, developed a scope of work that I know fully complies with applicable laws, only to have the rug pulled out from underneath me by a responsible agency that often lacks direct knowledge of on site conditions and who’s sense of compliance is often dictated by the immediate needs of a permit applicants. Having developed thousands of work scopes for every imaginable type of project, I have yet to find a project where scoping doesn’t come down to money, schedule, and sometimes both. How much, how long…the responsible developer then asks 1. What would be a bare minimum scope of work? 2. What would represent a top of the line, money is no object effort? 3. Where is a balance between the two? Developing an archaeological scope of work may not be brain surgery but it should be a thoughtful process that considers the nature of the project and its potential for effect; the potential archaeological sensitivity of an affected location; depending on applicable law(s), American Indian cultural and religious sensibilities; and it must recognize the political realities within the responsible agency(s). Brain surgery? No. Developing a defensible archaeological work scope does however require knowledge of applicable laws, considerable finesse, and a broad understanding of applicable methodologies and methods therein, which only comes after an appropriate education and considerable practical experience.
Some further thoughts: The reporter stated emphatically, “[h]owling winds uncovered a human tooth and a handful of bone fragments the size of quarters on a sand dune in the shadow of new solar power transmission towers. Indians say the discovery is evidence of a Native American cremation site not detected in Southern California Edison’s archaeological survey before the towers were built.” A few questions: 1. What does the archaeological survey report say about this locality? Often, a report will say identify a potential for buried archaeological materials exists in which case an archaeological monitor might be recommended during construction or sometimes the report might state that if anything archaeological is found during construction work should until an archaeological can evaluate the discovery. Does the reporter have the slightest clue what the report recommends or doesn’t that matter? 2. What were the physical conditions on the project site at the time of the archaeological survey? It sounds to me as if what Native Americans found was uncovered by unusually high winds. If these materials were in fact buried, why would anyone expect them to be found during a surface walkover? 3. If nothing was present on the ground surface at the time of the investigation, did the consulting archaeologist consider the potential for buried deposits? If so, were any specific recommendations generated to address these concerns, and, were these recommendations accepted/rejected by the responsible agency(s)? 4. Did the consulting archaeologist consult with relevant tribal organizations and individuals before fieldwork? What information was exchanged (if any)?
Finding archaeological objects the size of quarters when they are all or partly buried in sand and sparsely dispersed over a landscape would be difficult under the best of field conditions. There are methodologies that can assess potential for buried archaeological deposits but unless a responsible agency requires them then they are not typically part of the Phase 1 investigation. If the consulting archaeologists suspect buried deposits, s/he might propose additional investigatory work but it would be up to the responsible agency to require that this work be completed. It’s worthwhile to keep in mind that contemporary American archaeology seeks to avoid digging so we don’t just dig unless there’s a justification for doing so.
I shall conclude with Devil’s advocacy. Americans don’t support nuclear energy development for sound reasons. Americans are increasing amendable to the fact that fossil fuel development promotes global warming. Precisely where do Americans expect their energy to come from? Politicians have be crowing about alternative energy sources for years but these sources have no infrastructure and it was obvious years ago that creation of new infrastructure would create considerable environmental effects. If Americans think solar energy develop creates environmental effects, wait until US energy interests begin developing the nations extensive shale oil resources. Short of nationwide protests on a massive scale, these resources will be developed and if they aren’t then people had better get used to rolling black outs and ever diminishing energy resources. I see no efforts on the part of most world nations to curb population growth and the accepted globalization economic model requires between 2% and 3% annual economic growth to avoid recession. Conservation is an elegant solution but it won’t solve American near term energy needs. I suspect we’d have to slow economic growth considerable but that would mean fewer jobs, which is political untenable. Distributed energy is a wonderful idea but an awful lot of people needing energy don’t live in places conducive to energy generation, which means that for the foreseeable future we need centralized energy development to provide ener4gy for those unable to generate their own—unless of course those who can self generate support letting those who can’t do without (this too is political untenable). When I first heard about solar development in the Mohave several years ago, it was clear that it would conflict with many desert natural and cultural resources. These conflicts can be resolved most of the time but there are times that competing interests simply have to accept compromises unpalatable to all. The only surprise in this article is that it’s taken years for the LA Times to figure out that conflicts exist. Does the LA Times offer any useful solutions? As far as I can see, they’re primarily interested in controversy since that’s what sells newspaper copy.

Thoughts on Celtic Europe

I posted this in response to an item on LinkedIn concerning Celtic Iron and Greco-Roman Age hill forts and settlements in Thrace and recall posting further information about this subject several weeks ago. Another item was posted concerning the discovery of Indo-European Caucasoid skeletal material in the Tarim Basin of western China that the UK Independent reported as Celtic, which is of course an improper and inappropriate expansion of the term Celtic to a region they never inhabited. So the Celts….

There were certainly a large migration of people from Central Europe westwards in the early Iron Age but whether these people reached UK as an ‘invasion’ is now a minority view. The arrival of the Belgae in southern Britain after c 200 BCE however, is widely considered an invasion since this is attested to in Caesar’s Commentaries on the Gallic War. Whether it can be seen in the archaeological record is subject to interpretation. Be that as it may, exchanges with the mainland are a significant characteristic of the British Iron Age and movement of people back and forth between Gaul/northern Spain and Britain, and vice versa was probably not uncommon. This post and one from perhaps three weeks ago got me to thinking about Celtic occupations in the Balkans generally and the Carpathian Mountains in particular. Initially, I wondered if perhaps Celtic people moved eastward directly into the Balkans from the plains to the east but after more reading, I’m doubtful.

What about Celtic culture in Europe? I should first say that what follows is a somewhat traditional version of Celtic history. I’d like to read Cunliffe’s (1997) interpretations because it is my understanding he argues for a less unified history. Perhaps the earliest archaeological culture that might be viewed as Proto-Celtic is the Late Bronze Age Urnfield Culture of Central Europe from after 1250 BCE. Thus, on mainland Europe, the first culture that can be truly linked to Celtic is the Hallstatt Culture spanning central Europe, with its center in the area around Hallstatt in Central Austria. According to James (2005:21), Hallstatt occurred in 4 stages: Late Bronze Age A & B (c 1200 to 700 BCE); Early Iron Age C (c700-600 BC); and Iron Age D (c 600 to 475 BCE). Furthermore, Hallstatt exhibited two distinct cultural zones: The Eastern, including Croatia, Slovenia, western Hungary, Austria, Moravia, and Slovakia and the Western, including northern Italy, Switzerland, eastern France, southern Germany, and Bohemia. The culture is commonly linked to Proto-Celtic and Celtic populations in its western zone and with pre-Illyrians in its eastern zone.
In early Hallstatt, distance trade in copper, tin, and amber had already been well established with the first two items the requirements for manufacture of bronze. After c. 700 BCE, long distance trade in iron was established. The Hallstatt Culture area already controlled trade in salt, which was an important item for food preservation. Control of iron and salt provided the basis for the accumulation of wealth and influence and after c. 800 BCE status can be detected in central European human grave by such grave goods as wheeled wagons and iron swords.

Perhaps the best known cultural feature of Hallstatt D are fortified hilltop settlements north of the Alps or hill forts. These settlements exhibit burial mounds with high quality grace goods such as wagons and items from distance trade that possessed high intrinsic value. By Hallstatt D these increasingly rich burial mounds were clustered around a few major hill forts to the southwestern portion of the Hallstatt region, suggesting development and a concentration of wealth and social power possibly based on the development of the modern day Marseilles as the Greek trading port Massilia. As is commonly reported throughout the world, increases in luxury trade items increasingly stratified Hallstatt society that James (2005:21) suggested appears to have created a wealthy upper class.

By the 6th century BCE, Hallstatt extended for some 1,500 miles from the Champagne-Ardenne in the west, through the Upper Rhine and upper Danube rivers, to the Vienna Basin and east to the Danubian lowland, and from the Main, Bohemia, and the Little Carpathians in the north to the Swiss plateau, the Salzakammergut and to Lower Styria. The type site for this culture is Hallstatt, a lakeside village in the Austrian Salzakammergut southeast of Salzburg.

The La Tène Culture developed out of Hallsatt D and archaeologically and while there doesn’t appear to have been any significant cultural hiatus, it exhibits significant influences from contemporaneous Mediterranean cultures such as the Golasecca Culture of northern Italy (9th-4th centuries BCE), Greeks at Massilia after the 6th century BCE, the Etruscans of northern and central Italy after 700 BCE, and perhaps the Italian Villanovan Culture before 700 BCE. La Tene is named after the site in Switzerland where it was first discovered and it is these people that the Romans referred to as Gauls. La Tene is thought by many to be a time of Celtic expansion and migration, and when common Celtic myths formed. Originally found in an arc extending from eastern France to Bohemia, La Tene spread rapidly after c 400 BCE. La Tène Celts settled Spain in 450 BCE and northern Italy in 400 BCE (invading Rome in 390 BCE); they invaded Greece in 279 BCE, perhaps settling in the Carpathians at this time, and Galatia in 270 BCE. By 200 BCE, they occupied lands in Britain, Netherlands, Brittany, Belgium, Germany and Switzerland.

Cunliffe posits localization of La Tène after the 5th century BCE, with “two zones of power and innovation: Marne–Moselle in the west with trading links into Po Valley by way of the central Alpine passes and the Golasecca Culture, and, Bohemian in the east with separate links to the Adriatic by way of the eastern Alpine routes and the VeneticCulture” in the Italian Veneto. Cuniffe suggested settlement center shifts in the 4th century BCE. Even more radically, Cunnliffe (1997:26) stated that,

“Could it be that, far from being a language introduced by invaders or migrants moving in from Central Europe, [Celtic] was the language of the indigenous Atlantic communities , which had developed over the long period of interaction beginning in the fifth millennium B.C.”

If Cunliffe is correct, this give Celtic culture very deep roots in the European Atlantic! (these assertions pale in comparison to his comments on ‘what is a Celt! He argues that the question of “[w]hen did the Celts first arrive in Britain” relies on “too simplistic a view,” and then he demolishes the second of the great Celtic myths, that there was a pan-Celtic European culture and society that was self-aware and self-identifying).

There is much debate over how much of the expansion into Britain was achieved through either/or invasion and settlement and how much was the expression of cultural transfer that accompanied trade and reflected the commonality of kinship and language of many tribes. There is little evidence for actual migration of La Tène into Britain (James, 2005: 12) although I suspect Cunliffe might disagree with James. It appears that La Tène was more militarily-focused than the Hallstatt one and Cunliffe notes that some moved into the Mediterranean world as mercenaries. La Tène graves possess iron weapons, including swords and spearheads, and wooden shields, along with utilitarian items such as razors, yokes, cauldrons, and jewelry.

La Tène material cultural is found from the Atlantic seaboard through northern Spain, the Burgundy region of France, into Switzerland and Austria, and elaborate La Tène burials reveal a wide trading network. For example, in Vix, France, an upper class woman of the 6th century BCE was buried with a bronze cauldron made in Greece. Exports from La Tène cultural areas to the Mediterranean cultures were based on salt, tin, and copper, amber, wool, and leather, furs, and gold.

Cunliffe, Barry
1997 The Ancient Celts. Oxford: Oxford University Press.

James, Simon
1993 Exploring the World of the Celts.

Need to add morecitiations…later.

Parallels between Contract Archaeology in Ireland and California

The parallels between contract archaeology in Ireland, California, and the United States more generally are remarkable.   I began archaeology in the pre-contract archaeology era, and since 1975, I have held every position one can hold from volunteer excavator to principal investigator to owner of a company (for 30+ years). I have worked for a large university-based program, local government planning agency, the Federal government, as a graduate student intern for aCaliforniastate resource protection agency, and as a university instructor.  I have seen the profession from all perspectives over an almost 40-year period and while I cannot speak about Irish archaeology, I can state that your summation is a reasonable approximation of contract archaeology inCalifornia.  I have often thought about writing a personal assessment of the profession but when I had a real interest, I never had the time, and now that I have the time, I have no real interest.  I suppose it would be fair to say that I have become cynical and since I am at an age close to retirement, I would prefer leaving without leaving a parting shot to those left behind.


UnlikeIreland, there are no licenses inCaliforniaor theU.S.generally; meaning that, anyone calling him- or herself an archaeologist can conduct investigations providing they can get a land developer to pay for the work and an agency to accept it.  There is a Society for American Archaeology voluntary registry but I found the ethical statements to be incomprehensible in light of the contract reality (meaning they represent academic wishful thinking) and the requirements for listing to be little more than systematic justification for the graduate program status quo; hence, I resigned years ago.  Inasmuch as an advance degrees provide no guarantee that an archaeologist possesses the qualifications and capabilities to conduct an investigation within a regulatory framework, what we have in the US is a plethora of graduate students coming out of university with perhaps a year of academic field experience and an advanced degree but unable to gain academic employ.  Naturally, they hang out a shingle or find employment with a ‘full service’ environmental corporation.  Then, they proceed to botch project after project.  How do I know this?  The list of the project’s I’ve been retained to ‘fix’ started by registered individuals who lacked skill set to conduct contract projects is a long one.


As inIreland, land developers generally hold have the upper hand, especially for projects involving local government agencies…as opposed to state and federal agencies.  All local agencies inCaliforniaare required to implement state environmental protection laws but many do so grudgingly.  Most lack professional staff meaning that peer review and administrative oversight is absent, and elected officials often direct these agencies to promote economic development while giving a wink and a nod to state laws (justified by calling them an unfunded state mandate).  At the local level, archaeology is often perfunctorily performed, frequently with no emphasis on quality or adequate reporting.  With federal, and to a lesser extent, state contracts there is much m ore diligence regards final product but it varies greatly depending on the primary charge of the agency:  Some agencies have excellent programs while others have programs in name only.  Even when there are planning and resource protection ordinances at the local level, the only enforcement tool is litigation, and given the cost for litigation, when a land developer ‘accidentally’ destroying an archaeological site they are rarely fined or prosecuted.  Making litigation difficult has been court judgments stating that all the law may require is a fair and reasonable effort:  Excellence is not required.


Like Ireland, the contract profession is profit driven and it is typically a race to the bottom line with the quest for billable hours the primary concern, to the extent that a primary object is to keep all work in house:  If staff cannot perform the study, or make a half assed effort to that end, then the study is simply not recommended (geoarchaeology, paleobotany, interpretation or aerial photographs, adequate mapping, technical editing, etc.).  Final reports are quite frequently, especially on small local agency required surveys, hardly worth the paper on which they were printed.  In fact, we often see a simple compliance form employed with check boxes for many data categories (presence or absence).


Indeed, archaeology has become big business.  In the mid-1990s, I had 17 full time staff and I came to understand just how powerful the quest for billable hours could become.  Low balling (presenting teaser costs to get a contract and than using contract modifications to inflate total costs), professional back stabbing,  name calling, out bidding the competition by proposing unrealistic schedules…in short, lack of professionalism is profound and commonplace in large part because contracting is under-regulated and in many instances not regulated at all.  I have always been disturbed by unwillingness by many contractors to acknowledge that a large staff cannot fully mitigate a schedule that fails to provide adequate time for thoughtful analysis by the person responsible for the final product.  Certainly, we may employ skilled staff to perform many project tasks but a large competent staff cannot replace the thought process, which by definition requires time.  Inadequate thinking often becomes painfully evident in a final report.  I have turned down projects because of schedules seemed unreasonable and inflexible.  I believe however, that with many years of regional experience, proposing some schedule at the outset of a project is reasonable and justified.   Naturally, any schedule must be flexible and subject to change based on changed circumstances.  I typically estimate a schedule and then for contract purposes double it.  This work well enough.  I work most efficiently within a schedule as long as it is reality based.


I support licensing and sanctions for unprofessional conduct but that is not going to happen anytime soon in theUnited States.  Anyone operating in the contract archaeology venue must play by the rules of the market but when the market lacks practical rules, it means that anything goes as long as one doesn’t get caught breaking the rules…but since rules are so poorly defined, one cannot get caught???  Like you, I am bothered by a ‘holier then thou’ attitude some archaeologists possess.  This is a reminder that humans have an ability to justify what they do regardless of what that may be, while at the same time criticizing others for doing the same thing a slightly different way.  I find it best not to criticize because most of the details of contracting remain non-public and without full details any criticism is apt to be unfair are wrong headed.


When one employs a staff for many years, it is common to learn about their families and their cash flow needs.  Being a poor businessperson, I typically paid staff and consultants before paying myself and I refused to take the usual short cuts on projects.  After almost ten years with a big staff, my partner and I decided that the stress was too much.  I took a sabbatical and let my staff go as projects were completed.  After 18 months, we began the process of rebuilding…with home offices for my partner, myself, and one associate.   There was no focus on billable hours, we typically completed projects sequentially, and after 5 years, our income stabilized.  I also found had total control over my projects and I could actually turn down work located too far from home, that seemed uninteresting, that paid too little, or was offered under terms I did not approve.  At that point in my career, we possessed the good sense to know when a client was likely to be honest and when they were likely to be dishonest, and we walked away from a third of the projects we were offered largely because we did not like the client or the project.  We developed a stable clientele that came to us sole source or on personal recommendation and all was well until the economic collapse in late 2007.   In other words, after 1996, I played by my own rules and prospered.


Years ago, there were complaints in theU.S.about any use of mechanical excavation techniques but these days, mechanical excavators are commonly employed in contract archaeology.  For me, developing site stratigraphy is every bit as important as artifact collection.  Typically, labor is the single most costly aspect of archaeological investigation we are under constant pressure by regulatory agencies to develop methods for lowering labor costs without losing data.  As a practical matter, it would be lovely to excavate every site meticulously but if we did that, many archaeological sites would be lost to land development.  Therefore, contractors should focus on striking a balance between the ideal and reality.  Working around heavy equipment has therefore become normal in theU.S.


Regarding outright fraud, I have completely almost 4,000 individual projects and in only two instances, each many years ago, was I ever approached with a bribe.  In both instances, I explained that a successful bribe would have to be sufficient for me to retire, in which case the bribe amount would greatly exceed to cost for the work.  In my opinion, archaeological contracting has aged sufficiently so that those involved with land development recognize that an uncooperative contractor can always be replaced and the cost for replacement is always cheaper then paying a bribe:   The quest for billable hours at any cost is so powerful and prevalent, the need for bribery simply does not exist…contractors can and do cut their own throats by low balling, back stabbing, and price cutting.  Honestly, some archaeological contractors simply conduct work at a loss without comprehending the damage they do to the profession as a whole by charging a lower hourly rate that other contractors or skilled worker possessing far less education.


Concerning your ‘No One Spoke Up’ category, I agree with you completely.  I know a few people who never aspired to be anything more than diggers or square supervisors but they are exceptions.  Most excavators want to be supervisors and principals, and so they go on to graduate school for advanced degrees.  That fact diminishes efforts to unionize.  I agree that people leveling criticisms often have little understanding of the situations for which they are being critical.   This is especially the case with contractors criticizing the work of their peers.  Until one learns the particulars of a contract, in particular the limitations or enforced conditions within which a contractor must work, criticism is rather meaningless.  If I am faced with an unworkable situation or unethical conditions, I may proceed exposing myself to possible criticisms or I may politely resign.  Resignation however, does not free me to attack a former client or the archaeologist replacing me since I typically possess proprietary information often covered by contract non-disclosure clauses that remain in force even if I resign from a project.


In 1990, my business was at its peak and I took a salary of about $90k per year plus an additional 20% from company profits.  Considering that my partner and I took on all the professional and financial risks and all of the stress, I do not think this was an unreasonable amount.  The key issue for me is whether one makes money off the backs of others.  We always paid our staff on time and above the median wage.  We paid adequate living and lodging expenses and we never cut corners technically or with safety.  I am not aware of any contractor inCaliforniamaking hordes of cash at the expense of the resource or their employees but I have heard numerous reports to this effect.  I am aware that contractors have made hordes of money at the public’s expenses by paying their employees a decent hourly wage but over charging the public agency (staff wage $25/hr and billing at $100/hr).  This is unfortunate.  If anyone wishes to find graft, waste, and chicanery, I suggest looking at American defense contracting.  I make a decent living, or at least I did until the latest economic woes.  I look at my pay this way:  I am paid to do what I love what I do.  How can anyone complain about that?  People toil away for a rapacious corporation like Wal-Mart for minimum wage with crappy benefits all to make rich people richer.   For a kid who loved playing in the dirt, I am paid to play in the dirt.  Sometimes the pay is lousy but it beats working at a job that is tedious and merely a ‘job.’


Archaeologists in theU.S.have an over-inflated sense of the importance of their work and I do not sense they understand how precarious our collective position is in light of the fact that our government willingly cuts food and health benefits to children.  Archaeology is indeed an expendable service, certainly ranking below clean water and air, and preservation of rare and endangered species.  If protections for the latter are being served up to transnational corporations so that they can determine how to ‘protect’ these essential human resources, we should understand that protection of archaeological resources, could easily be eliminated.


In closing, let me say that I never read the blog post to which your response was directed.  I doubt if I would have made it through the posting because I have no time for naive hyper-moralistic people.  Whether we like it or not, the profession of archaeology has very much become a business and the profession must accept the benefits and realities of markets.  Whether archaeology remains a business, at least in theU.S., is problematic.  I am reasonably convinced that good science and profit motive are incompatible and in my view, hundreds of millions of have been wasted on ridiculous compliance efforts without generating worthwhile knowledge.  In many instances, the focus has become compliance with laws and regulation for the sake of compliance and generating billable hours.  Land developers do not care about archaeological data; they want their permits to construct and whether their funding of research adds to the sum total of our knowledge of past human activity is irrelevant as they get to build their project and make money.  I would like to see archaeology re-academicized at least to some extent.  However, I do not think a return to academia is the answer because contract archaeology has made significant methodological contributions to the field that should not be ignored and I would expect additional contributions in the future.  Market forces do keep any field of endeavor from ossifying.  Contracting has also demonstrated the need for archaeologists to keep the public informed of their work since even when it was confined to academia, the public that ultimately paid the costs for most of our dirt digging.


What you wrote took a great deal of courage; at least in my opinion.  I would not have written a response because my response would fly in the face of conventional professional wisdom and I have no desire to take on the profession.  I am however glad that you did in fact respond the way you did.

Creating a spatial database for archaeological survey

When we complete archaeological investigations focused on resource identification before we set foot in the field we collect as much information about the location of interest as possible from historical and modern maps, and aerial photographs, soil and geological surveys, and, previous archaeological investigations.  The most suitable base map should be the map judged most accurate for the purpose keeping in mind that the larger the scale the more computing power and storage capacity required.  We usually work with engineering maps generated from recent aerial orthophotography often at a scale of 1:200.  The map and the original aerial photography form our base.  Engineering maps typically have 3 ft contour intervals and they show significant vegetation, structures, and other modern development features, watercourses and springs, and often rock outcrops but as we shall see they have certain disadvantages that must be addressed


U.S. state and federal agencies responsible for keeping track of archaeological and historical resources employ the 7.5-minute topographic quadrangle.  These maps are scaled at 1:24,000 and adhere accuracy standards.  Since the 1940s they have been generated from aerial orthophotographs of the same scale and we employ both maps and photography as a separate but connected map base.


Why do we employ two distinct sets of baseline data?


Most private sector clients require archaeological site plots on engineering scale maps (if available) as these are the maps used for project planning while U.S. government agencies tracking archaeological site locations use the 7.5-minute USGS map series.  Further, all archaeological site information filed with state agencies has been plotted on USGS 7.5-minute topographic maps and these data are routinely collected and used in our fieldwork and fieldwork planning.  Since we are ultimately required to present two sets of maps, one at an engineering scale and one at USGS scale it makes sense to maintain two interconnected sets of baseline spatial data.


One disadvantage working with engineering maps is that engineers often work in what is called ‘local grid.’  What this means is that their project area maps are not linked to any real world grid such as UTM and latitude/longitude.  We prefer using the metric UTM grid since that is the system preferred by government agencies and American archaeologists but one may select any grid including latitude and longitude because modern mapping programs such CAD and GIS convert grids.  Changing grids means a little extra work but it is not a major difficulty.


Depending on project area size, one might need to select a map projection.  The 7.5-minute USGS map series employs a polyconic projection with older maps using the 1927 North American Datum (NAD 27); more recent 7.5-minute maps switched to the 1983 North American Datum (NAP 83).  There is a significant horizontal difference between them.  As with grids, modern computer mapping programs can correct for different datums but this requires an additional step.  Our projects rarely include more than several thousand acres (2.2 acres per hectare) and so projection is rarely an issue but selection of NAD 27 or NAD 83 is important.  Inasmuch as all revised USGS maps employ NAD 83 that is the datum we employ.


Once we have established our two base maps with corresponding aerial photography, we begin collecting ancillary data.  For reconstructing modern landscapes, when available we collect sequential aerial photographs from each decade.  Much ofCaliforniawas photographed by theU.S.government beginning in the late 1930s and except for mountainous regions we have had little difficulty collecting aerial photographs from each subsequent decade.  Some parts ofCaliforniawere selective photographed by private aerial photography companies (e.g. Fairchild Company) as early as the late 1920s.  In fact, the earliest aerial photography in theU.S.occurred inCaliforniain the late 1920s.


Depending on the size of a project, we orthographically correct each aerial image that is incorporated into a spatial database.  For projects of a few hundred acres, ortho-correction is typically unnecessary but on projects exceeding several thousand acres it becomes more important.  The real world grid location of each aerial photograph however, must be determined since this is not indicated on the image.  For plotting image location to real world grid, we look for at least four clearly identifiable points that appear on modern USGS orthophotography (the more correlated points, the more precise the fit but if we can identify at least four we know that accuracy will be within a few feet).  Each aerial photograph scanned into the spatial database must be correlated with the USGS orthophotograph.


Once images have been located in real world grid, we begin the process of interpreting them.  Images are scanned as raster files (.tif) and then using CAD or GIS computer programs, we then trace locations of identified cultural features, archaeologically sensitive areas, important natural features, modern features, etc into unique vector files (.arc, .dwg, .dxf) with each file forming yet another piece of the overall spatial database.


Once we have interpreted each aerial photograph and created a unique vector files for each, we examine historical maps (for example, historical topographic maps, General Land Office plat maps from the original national land surveys, Sanborn Fire Insurance Maps for cities and towns, maps of mining areas, pre-World War II County road maps, etc).  These maps are scanned as raster images (.tif) and, if necessary, notable historical features are traced into vector files unique to each map.  Depending on the project, we may request biological data from the project’s consulting biologist and use those maps to create raster and or vector files for rare and endangered species, trees, brush fields, and watercourses (many biological features are protected under state and federal laws when we develop an archaeological mitigation plan we attempt to incorporate significant archaeological sites into required biological set aside areas).


We create a vector file for modern, existing infrastructure typically generated by the project engineer.  When available, we employ near infrared aerial photography, and space shuttle and or satellite imagery as appropriate.  These images are useful for identifying specific types of vegetation and locations of surface or near surface water.  In fact, any suite of remotely sensed data may be readily incorporated into a spatial database as long as data can be correlated with four or more points on base imagery.


We can link spatial data to terrestrial photographs and data as the need occurs.  Using DTM or DEM software, we may create three dimensional models of topography for geovisualization, and, models for surface analysis of gradient, aspect, and visibility.  A Coordinate geometry computer program can be used to create maps of complex structures, walls, ruins, etc and these vector files can be easily incorporated into the spatial database.


A complicated geospatial database for a large project might have as many as three dozen or more unique files.


Data integration can be both tedious and time consuming but once each image is correctly and accurately linked to a base map via real world coordinates, the computer performs most of the tedium.  However, we visually check each associated data file with the base to ensure correct fit.  We do this because we work with data representing different levels of accuracy, base datums, and projection but primarily because much of our data is analog (paper) and we deal with tremendous levels of distortion.  Thus, although we might provide a computer program with correctly inputted data, distortion caused by wrinkles, creases, even the reproduction process make it necessary to visually verify the end result.  When we detect errors; that is, when digital files simply will not overlay properly, we make manual adjustments to achieve image fit.  This may be done by shifting the entire image, changing the scale of offending files, or using a stretching program.  File stretching is tricky and one must remember that a ‘pretty picture’ may not reflect on-the-ground reality.  Some programs have an analysis feature that calculates the best fit and this offers a more precise method then attempting to a manually stretch and fit two or more files.


This discussion represents an outline in the simplest terms possible the sequential efforts we use to create a spatial database on our projects. There is a great deal more detail to effort.  Sometimes we must restore or enhance images that may be washed out or darkened.  Some images have numerous scratches, the most significant of which should be removed.  When dealing with a badly stressed analog image often the best approach is to trace information from the image and then archive the raster image using the vector file in the spatial database.


It is important to remember that a spatial database is only as accurate as its least accurate element.  Fitting a 7.5-minute USGS topographic map with a scale of 1:24,000 into an engineering map with a scale of 1:200 will not improve the accuracy of the former even if one achieves a reasonable correlation of mapped features.  Yet, the former may degrade the accuracy of the latter if the two maps are integrated.  For example, an archaeological site plotted on a 7.5-minute quadrangle can be digitally correlated to an engineering scale map but the accuracy of the plot will remain 50 to 100 ft, which is the general accuracy of the map from which it was extracted.  When working with such data in the field, this can create a deceptive situation and one must be aware of this.  When we generate a composite map for fieldwork, we typically generate both topographic maps and aerial photographs using both USGS and engineering map scales.  This allows us to see how plotted features fit on to our two base maps.  We can then and compare the mapped data to what actually exists on the ground.


As we complete our work, we create yet another file from GPS data points.  Our hand held units have a horizontal accuracy ranging from 6 ft to 10 ft.  To achieve greater accuracy, we not only generate GPS plots but we map archaeological sites as accurately as possible on engineering scale aerial photographs, which can be done with a high degree of accuracy.  We can then compare our GPS archaeological site plots to our aerial photography mapped locations.  There is usually reasonable correlation between the two sets of data but we tend to favor aerial photography locations and adjust GPS data as necessary.  When we need highly accurate GPS data, we contact the project engineer to get a professional survey crew to map specific locations using differential post processing GPS; for example, when an archaeological site appears to conflict with proposed infrastructure.


Creating a spatial database requires a great deal of up front time but we have discovered that effort pays dividends during fieldwork.  When we walk onto a project area, we know the locations of surface or near surface water, existing and historical roads and trails, in fact anything that is or was visible on aerial photographs and maps is plotted on our field maps.  I would estimate that our approach cuts 20% off our field schedule.  Further, some forms of analysis cannot be easily undertaken without digital spatial data.