Latest updates:

November, 2004-

Thank you to all who helped us out during the 2004 field season- this includes everyone who donated to our project, helped us in the field at Pusilhá, Minanhá, and Baking Pot, or followed our progress by watching our updates online.  Overall the season went well; we collected huge amounts of information- enough to keep us busy for years to come.  Presently we are in the process of doing report write up and preliminary analysis of conductivity data.  We are also giving some thought to the necessary follow up work at this seasons' sites.  And of course we are considering our options for future work. 

As always, any help for our future operations are welcome and greatly appreciated.  You may contact us by phone at  303-926-9318 or e-mail TSweely@BEMEP.org.  

The Project

Introduction

The ancient Maya of Mexico and Central America once evoked images of an elusive, perhaps violent, lost civilisation, known only to adventurers, scholars of adventurous constitution, and Hollywood.  With modern technology, the Maya are not as elusive as once believed.  

The Belize Electromagnetic Explorations Program, or BEMEP, was co-founded in 2002 by archaeologists Gerald Trainor and Tracy Sweely.  As independent scholars, and essentially volunteers, Trainor and Sweely rely on their passion for archaeology and  their desire to enhance and contribute to the discipline of Mayan archaeology to drive them and to see the project through to completion.  Being an independent project, there is little funding available for BEMEP.  Funding for the 2003 Reconnaissance was provided in part by the Prehistoric Society of London.  Funding for the 2004 field season is being sought through various private and corporate donors, as well as the Foundation for the Advancement of Mesoamerican Studies and the Prehistoric Society of London.

The ancient Maya sites of Pusilhá and Minanhá, Belize (figure 1) are classified as medium sized centers in terms of population and presumed political integration (Braswell 2002; Iannone et. al. 1999).  Both sites have large, central  monumental architectural zones surrounded by increasingly smaller,  and less impressive in terms of labor expenditure, architectural remains.  Drawing on data collected during archaeological investigations (Braswell 2002; Iannone et. al. 1999, 2000, 2001, 2002) at the sites of Minanahá and Pusilhá, areas were chosen at these sites for further reconnaissance.  Field reconnaissance from  25 April, 2003 through 9 May, 2003 confirmed that the conditions necessary for using the geophysical prospecting technique of electromagnetic induction, or EM, appear to exist at both sites.

Using electromagnetic induction, BEMEP has as its goal the location of prehistoric features including non-platform floors, or hidden architecture- ancient Maya house floors that are not visible on the ground surface- in settlement zones.  These smaller remains, and the apparently vacant terrain in these "suburban" zones are the main focus of BEMEP.  Additionally, subsurface conductivity data will be collected from the large, central plazas at each site looking for burials, caches, offerings and previous construction phases within the central precincts.  These collected raw conductivity data are downloaded into a laptop at each day’s end and processed with the appropriate software program to create a two dimensional, subsurface map.  The maps are then used to locate our test excavation units.  Excavation  provides ground-truthing of our EM data and allows for more detailed data collection through traditional excavation procedures.   

The EM and excavation data, once fully analysed, will enhance our understanding of the predictive value of this geophysical prospecting technique.  Simultaneously, the archaeologically significant results of these surveys will provide data that will allow for the examination of the social significance of variation in dwelling types and their associated activity areas and the burial and caching practices revealed within the different settlement and plaza areas surveyed.  The results of the investigations will be presented at professional meetings, published in professional journals, presented at local slide presentations and published in popular publications. 

Timeline

In mid-March of 2004 BEMEP will return to Belize for Phase 2 of our project.  We will be in Belize conducting investigations for approximately four months, two months at each archaeological site. 

In 2005 we will return to Belize for Phase 3, follow up investigations, and pending further grant acceptance, more data collection.  The 2005 work is tentatively scheduled for the months of April and May.  However, if additional funding is found for the project we may extend our stay.

Electromagnetic Induction

The basic premise of the process of electromagnetic induction is that through measuring the ease or difficulty by which electrical current passes through the subsurface, subsurface maps can be created.   Electromagnetic induction, or EM, (also known as EMI, electromagnetic conductivity survey or conductivity survey) uses an electromagnetic current which is induced into the subsurface by way of a transmitting coil.  This current, after flowing through the subsurface, becomes attenuated, or dissipated in relation to subsurface composition.  The attenuated, reflected current is then detected by a receiving coil and its values are recorded by the machine’s data logging device.  This value, being an averaged conductivity reading, is known as apparent conductivity (Bevan 1983).  The apparent  conductivity data logged in the machine’s recording device is downloaded to a laptop at the day’s end and processed with the appropriate software program to create a two dimensional, subsurface map.  For a more detailed discussion of EM as well as other geophysical prospecting methods, see Clark (1996) and Bevan (1998).

There are a number of factors influencing the accuracy of data collection.  The machine itself, in our case the Geonics EM38 Ground Conductivity Meter, or EM38 (figure 2), requires calibration at the beginning of each day.  Checking of calibration is recommended at various intervals throughout the day in order to ensure continued accuracy in data collection (Geonics 2002).

Soil composition is a critical factor when using EM.  Soils that are too shallow, too rocky, or too wet are poor conductors of electromagnetic energy in terms of its applicability to archaeology.   Optimally, soils of 25 cm. to 1.5 meters in depth, obviously having cultural horizons within this range, are sought for use with the EM38.  The clayey soils found in southern Belize lend themselves well to EM survey as clay, in retaining moisture, is a good conductor of electricity.  These types of soils were encountered and found very favourable by Sweely (2002a, 2002b) in her research using the EM38 at the site of Chau Hiix in northern Belize.  Topographic conditions can also influence the ability to use the EM38.  The ground surface must be relatively and consistently level, and without excessive slope,  in order to maintain the EM38 at the height necessary for accurate data collection.  

 References Cited 

Braswell, Geoff

2002    Pusilhá Archaeological Project 2001 Annual Report.

Bevan, Bruce

1998    Geophysical Exploration for Archaeology: An Introduction to Geophysical

Exploration.  Special Report No. 1.  National Park Service, Midwest Archaeological Center, Lincoln, Nebraska.

1983     Electromagnetics for Mapping Buried Earth Features.  Journal of Field

Archaeology,10: 47-54.

Clark, Anthony

1996    Seeing Beneath the Soil: Prospecting Methods in Archaeology, Revised.  B.T.

Batsford, Ltd., London. 

Geonics Limited

2002    EM38 Ground Conductivity Operating Manual.  Mississauga, Ontario,

Canada: Geonics Limited.

Iannone, Gyles, Jeffrey Seibert, and Nadine Gray (editors).

1999     Archaeological Investigations in the North Vaca Plateau, Belize:  Progress Report of the First (1999) Field Season.  Department of Anthropology, Trent University, Peterborough, Ontario. 

Iannone, Gyles, Lisa McParland, Adam Menzies, and Ryan Primrose (editors).

2000     Archaeological Investigations in the North Vaca Plateau, Belize:  Progress Report of the Second (2000) Field Season.  Department of Anthropology, Trent University, Peterborough, Ontario. 

Iannone, Gyles, Ryan Primrose, Adam Menzies, and Lisa McParland (editors).

2001     Archaeological Investigations in the North Vaca Plateau, Belize:  Progress Report of the Third (2001) Field Season.  Department of Anthropology, Trent University, Peterborough, Ontario.

Iannone, Gyles, et. al.

2002     Archaeological Investigations in the North Vaca Plateau, Belize:  Progress Report of the Fourth (2002) Field Season.  Department of Anthropology, Trent University, Peterborough, Ontario.

 McNeill, J.D.

1980     Electromagnetic Terrain Conductivity Measurement at Low Induction Numbers.  Technical Note TN-6, Mississauga, Ontario, Canada: Geonics Limited.

Sweely, Tracy L. 

2002a    Detecting "Invisible" Dwellings In The Maya Area Using Electromagnetic

             Induction: Significant Findings Of A Pilot Study At Chau Hiix, Belize.  Submitted

2002b   Geophysics at Chau Hiix: Ongoing Investigations.  Paper presented at the 67^th Annual Meeting of the Society for American Archaeology, Denver, CO.