CARBON DATING THE IMAGE OF APO STO. CRISTO DE LUBAO

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AWARDED DIAMOND (FIRST) PRIZE RESEARCH
by the International Association of Multidisciplinary Research (IAMURE)
at Marriott Hotel, Jakarta, Indonesia
on January 21-23, 2013.

I. INTRODUCTION

Oral history is the collection and study of historical information about individuals, families, important events, or everyday life using audiotapes, videotapes, or transcriptions of planned interviews. These interviews are conducted with people who participated in or observed past events and whose memories and perceptions of these are to be preserved as an aural record for future generations. Oral history strives to obtain information from different perspectives, and most of these cannot be found in written sources.

Oral history has become an international movement in historical research. Oral historians in different countries have approached the collection, analysis, and dissemination of oral history in different ways. However, it should also be noted that there are many ways of creating oral histories and carrying out the study of oral history even within individual national contexts.

Along this premise, the elders of Lubao, Pampanga, (Lubao is considered to be the Cradle of Kapampangan Civilization and Christianity) traditionally believed that the sacred Cross of the Crucified Christ was received by their ancestors led by Datu Macabulus after they capitulated to the Spaniards in September 14, 1571. Oral accounts indicated that the holy Image of the Crucified Cross was lost for a long period of time but was believed to re-appear sometimes in the middle of 1700. Since then, it was enshrined in barangay Sta. Cruz and is venerated by its countless devotees because of the countless favors and miracles the holy Cross has been sustaining them.

However, some people were skeptical about its authenticity and age; hence, this research. For this purpose, the investigatory research will employ the scientific inquiry method using carbon dating procedures as the primary method to yield empirical results.

Radiocarbon, or carbon 14, is an isotope of the element carbon that is unstable and weakly radioactive. The stable isotopes are carbon 12 and carbon 13.
Carbon 14 is continually being formed in the upper atmosphere by the effect of cosmic ray neutrons on nitrogen 14 atoms. It is rapidly oxidized in air to form carbon dioxide and enters the global carbon cycle.
Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes. When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay.

Radiocarbon dating is essentially a method designed to measure residual radioactivity. By knowing how much carbon 14 is left in a sample, the age of the organism when it died can be known. It must be noted though that radiocarbon dating results indicate when the organism was alive but not when a material from that organism was used.

The scientific results of the study will provide not only empirical information to the on-going inquest of the Research Office of the Tarlac State University along social, technological, cultural, industrial and scientific realms but will also supply the Philippines with additional and valuable literature vis-a -vis church heritage.

The results will bolster the authentication and validation of oral traditions through scientific inquiry. This study, which is a pioneering research undertaking in the university on radiocarbon dating procedures, will invite the attention of local government and church authorities to involve themselves in allowing their surviving treasures i.e. church antiques, ancestral porcelains and the like to undergo scientific examination to bolster their local pride and heritage; thus, a boost to local tourism industry.

The results of the study will not only serve as local pride to the Municipal Government of Lubao, Pampanga and Archdiocese of San Fernando, Pampanga but as a national pride for the Tarlac State University in the field of socio-cultural-ecclesiastical research in exploring new investigative frontier. Similarly, its impact will serve as a great contributory to the re-discovery of Philippine’s national history and heritage.

II. OBJECTIVES
The general objective of the study is to identify the age of the holy Crucifix using radiocarbon dating method. Specifically, it aims to carry out the study by identifying the age of the sacred Cross of the Crucified Image of Christ through radiocarbon dating procedures, and to provide scientific information to the people vis-à-vis results of the carbon dating analysis.

Specifically, the study aimed to:
1. Verify the age of the cross sample that was presumed to be brought by the Augustinian Friars in the Philippines in September 14, 1571 according to some documents and oral accounts through carbon-dating analysis.
2. For some time, the cross and the image were separated. To prove that the pieces are compatible, similarities in the matrices of radio-carbon data will justify that the two are compatible.

IV. METHODOLOGY
Methods and Materials

Radiocarbon dating (sometimes simply known as carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 (14C) to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years.

The technique of radiocarbon dating was developed by Willard Libby and his colleagues at the University of Chicago in 1949. Libby estimated that the steady state radioactivity concentration of exchangeable carbon-14 would be about 14 disintegrations per minute (dpm) per gram. He demonstrated the accuracy of radiocarbon dating by accurately estimating the age of wood from a series of samples for which the age was known, including an ancient Egyptian royal barge of 1850 BC. (en.wikipedia.org/wiki/Radiocarbon dating)
Using this investigative method, the objectives of the research were carried out with the results presented in the foregoing discussion.

This undertaking is an inter-agency research that endeavored to provide, facilitate, and conduct actual procedures in collecting samples to authenticate the oral tradition of the devotees of the Holy Cross of the Crucified Christ located in Sta. Cruz, Lubao, Pampanga, which they have been devoted with since time past.

The age of the holy Image was determined through radiocarbon dating procedures. The research was started January 2012 until April, 2012.

Initially, the researchers facilitated links with local and national agencies as regards protocols and carbon dating service providers. Unfortunately, no local radiocarbon dating agency in the country today is available to conduct the objectives of the research.

Finally, the proponents succeeded in connecting links with the Beta Analytic Inc. based in Miami, Florida, USA, which is probably one of the largest radiocarbon dating service providers in the world at present.

The Research and Development Office of the Tarlac State University through its Research Office provided technical assistance to the local government of Lubao, Pampanga. The municipal government of the town represented by Mayor Mylin Pineda-Cayabyab agreed to finance the services of the radiocarbon dating agency.

Collaboratively, the researchers created a working team composed of archeologist, chemist, planning officer, parish priests, carpenter, photographer, and municipal mayor to carry out the methods and procedures on the technical components of the project i.e. sampling, transport of samples, and the likes. Collaborations with the local parish priests, the Archdiocese of San Fernando, Pampanga and the
National Museum of the Philippines were made as regards the undertaking.

The radiocarbon dating agency provided the method and procedures with regard the technical aspects of the study. Classified as archeological artifacts, the samples were transported to the radiocarbon dating agency (Beta Analytic Inc.) via cargo flight of the Federal Express in Clarkfield Freeport, Angeles City, Pampanga.

Two weeks later, the radiocarbon results were provided to the researchers and chief executive of Lubao, Pampanga.
Wood samples were collected from the cross and from the image. Standard procedures were conducted prior to shipment to Beta-Analytic Laboratory for radio carbon dating:

A. Wood Collection and Sampling:

1. Select an area that does not show signs of rot or insect activity. Also make sure that the area does not show signs of being treated with shellac, oil, glue, other preservatives or additives.
2. Ideally the wood should be collected from the outer-most section of the piece, this will ensure that the outer-most growth rings are dated and provide the approximate time of death of the tree or branch, as close as physically possible.
3. Obtain two (2) new, wood twist-drill bits. Approximate size recommended is 5/32” for the first drilling and 1/8” for the second drilling. These drill bits should be cleaned prior to use with acetone to remove any machine oils and then allowed to air dry.
4. Drill a 5/32” hole approximately 1/4” to 3/8” deep and discard these drill shaving. It may be necessary to drill deeper if the wood is rotted or altered. Try to get some wood that has been isolated from any sort of surface contamination.
5. Lay the object on its side and place a piece of aluminum foil under the area to be drilled approximately 4” by 4” store bought foil is fine and requires no precleaning.
6. Drill the second hole with the 1/8” drill bit into the center of the 5/32” pilot hole and allow the shavings to collect onto the aluminum foil. Collect approximately 100-200 milligrams of wood sample shavings.
7. Once the shavings have been collected onto the aluminum foil, fold the foil such that you make a small pouch. Label the pouch with the sample code or name. Place this aluminum foil pouch in a zip-lock container and label.

B. Radio-Carbon Dating:

The samples were shipped for testing to Beta-Analytic Inc., known for more than 30 years; it is the pioneer in the radio-carbon dating business. It is the only radiocarbon dating laboratory accredited to the ISO 17025 standard. The samples were treated and analyzed as follows:

A. Principal Methods of Measuring Radiocarbon

chemical2

There are three principal techniques used to measure carbon 14 content of any given sample gas proportional counting, liquid scintillation counting, and accelerator mass spectrometry.

Gas proportional counting is a conventional radiometric dating technique that counts the beta particles emitted by a given sample. Beta particles are products of radiocarbon decay. In this method, the carbon sample is first converted to carbon dioxide gas before measurement in gas proportional counters takes place.

Liquid scintillation counting is another radiocarbon dating technique that was popular in the 1960s. In this method, the sample is in liquid form and a scintillator is added. This scintillator produces a flash of light when it interacts with a beta particle. A vial with a sample is passed between two photomultipliers, and only when both devices register the flash of light that a count is made.

Accelerator mass spectrometry (AMS) is a modern radiocarbon dating method that is considered to be the more efficient way to measure radiocarbon content of a sample. In this method, the carbon 14 content is directly measured relative to the carbon 12 and carbon 13 present. The method does not count beta particles but the number of carbon atoms present in the sample and the proportion of the isotopes.

B. Radiocarbon Dating Standards
The radiocarbon age of a certain sample of unknown age can be determined by measuring its carbon 14 content and comparing the result to the carbon 14 activity in modern and background samples.
The principal modern standard used by radiocarbon dating labs was the Oxalic Acid I obtained from the National Institute of Standards and Technology in Maryland. This oxalic acid came from sugar beets in 1955. Around 95% of the radiocarbon activity of Oxalic Acid I is equal to the measured radiocarbon activity of the absolute radiocarbon standard—a wood in 1890 unaffected by fossil fuel effects.
When the stocks of Oxalic Acid I were almost fully consumed another standard was made from a crop of 1977 French beet molasses. The new standard, Oxalic Acid II, was proven to have only a slight difference with Oxalic Acid I in terms of radiocarbon content.

Over the years, other secondary radiocarbon standards have been made.
Radiocarbon activity of materials in the background is also determined to remove its contribution from results obtained during a sample analysis. Background radiocarbon activity is measured, and the values obtained are deducted from the sample’s radiocarbon dating results. Background samples analyzed are usually geological in origin of infinite age such as coal, lignite, and limestone.

C. Radiocarbon Dating Measurements
A radiocarbon measurement is termed conventional radiocarbon age (CRA). The CRA conventions include (a) usage of the Libby half-life, (b) usage of Oxalic Acid I or II or any appropriate secondary standard as the modern radiocarbon standard, (c) correction for sample isotopic fractionation to a normalized or base value of -25.0 per mille relative to the ratio of carbon 12/carbon 13 in the carbonate standard VPDB – Cretaceous belemnite formation at Peedee in South Carolina, (d) zero BP (Before Present) is defined as AD 1950, and (e) the assumption that global radiocarbon levels are constant.
Standard errors are also reported in a radiocarbon dating result, hence the “±” values. These values have been derived through statistical means.

D. Accelerator Mass Spectrometry
Mass spectrometers detect atoms of specific elements according to their atomic weights. They, however, do not have the sensitivity to distinguish atomic isobars (atoms of different elements that have the same atomic weight, such as in the case of carbon 14 and nitrogen 14—the most common isotope of nitrogen).
Thanks to nuclear physics, mass spectrometers have been fine-tuned to separate a rare isotope from an abundant neighboring mass, and accelerator mass spectrometry was born. A method has finally been developed to detect carbon 14 in a given sample and ignore the more abundant isotopes that swamp the carbon 14 signal.

V. PRESENTATION AND DISCUSSION OF THE RESULTS OF THE RADIOCARBON DATING ANALYSES

chemical4

chemical5

As presented on the spread sheet of the results and the calendar calibration graphs, the results disclosed that at 2-sigma statistics (95% probability), 2 dates yielded overlapping ranges, indicating that the results are statistically identical. Overlaps occur at Cal AD 1680 to 1690, Cal AD 1730, Cal 1810, Cal AD 1920 to 1930 and post AD 1950.

In an inquiry with Ron Hatfield, the deputy director/quality manager of radiocarbon dating agency (Beta Analytic Inc.), he explained “the result means that if no recent contamination was introduced into the wood which could not be removed by the acid and alkali treatments performed, then the tree growth rings dated for each sample were last in equilibrium with the atmosphere (alive) in one of these ranges. “

As he further explained “radiocarbon dating cannot determine exactly which range the rings actually represent, but it is one of them for each sample.”

It is to be noted that the prior to the pretreatment (acid/alkali/acid) procedure, the deputy director suggested special pretreatment (acid/alkali/acid/cellulose extraction) considerations prior to the laboratory analysis. The suggestion was made due to the heavy presence of paint, varnishes, oils and the likes in the samples. Special pretreatment is necessary to maximize the reduction of chemical contaminants that allow cellulose extractions easier for final analysis. However, it may or may not yield significant result than the pretreatment protocol that also needed added cost. As prior agreed, the researchers opted and deemed for the pretreatment analysis to proceed.

Beta-316804 (The Wooden Cross) yielded ranges of Cal AD 1650 to 1690 (Cal BP 300 to 260), Cal AD 1730 to 1810 (Cal BP 220 to 140), Cal AD 1920 to post 1950 (Cal BP 30 to post 1950)

and

Beta-316805 (The Image of Christ) yielded ranges of Cal AD 1680 to 1730 (Cal BP 270 to 220), Cal AD 1810 to 1930 (Cal BP 140 to 20), Cal AD Post 1950.

If the expected age was somewhere around 1570AD as traditionally believed by the residents, the results indicated that the very oldest that the dates seemed to represent would be the overlap from around the time of AD 1680 to1690. This is to assume if all the growth rings dated from both the samples were the same.

Seemingly, the age appears to be about 100 years later than was expected. This would mean that either the actual time the cross arrived in Lubao, Pampanga was more recent than historically reported or that the wood was contaminated by more recent organics such as penetrated oils, varnishes, paints, etc.

As observed by the Mr. Hatfield, the wood samples looked physically very clean and similar but this does not rule out a more recent chemical contaminant such as those indentified above.

Where does the contamination emanate from?

There are considerations which should be noted on the results of the study. First is the ability of the radiocarbon dating technique (2 sigma calibration) results to predict perfect outcome due to some calculation error factor i.e. carbon dating test allows 5% probability of error. Second is the noticeable heavy contamination of the Crucifix with hardened coals, paints, varnishes, oils and the like that blackened the Cross and Christ’s Image. Largely, the presence of these chemicals is attributed to the cultural traditions of the people to preserve the Crucifix against deterioration. Hence, the huge contaminations are both ancient and recent, which probably and largely affected the results of the analyses.

However, Mr. Hatfield further noted and suggested that if the more recent ages cannot be resolved in terms of the historical reporting of the time of arrival of the Crucifix, then the only way to know if there was some effect from more recent contamination would be to take some of the remaining wood shavings for one of the samples that they are still keeping. After the special pretreatments has been performed prior the final analysis, a new date will reveal if the age comes in agreement with the historical reporting with regard the arrival of the Crucifix in the area. As previously mentioned, however, it may or may not produce new result.

VI. Summary of Findings

1. Radiocarbon dating analyses showed that Beta-316804 (The Wooden Cross) indicated a measured radiocarbon age Cal AD 1650 to 1690 (Cal BP 300 to 260) compared to Beta-316805 (Image of Christ) Cal AD 1680 to 1730 (Cal BP 270 to 220).

2. Results disclosed that at 2-sigma statistics (95% probability), 2 dates yielded overlapping ranges, indicating that the results are statistically identical. Overlaps occur at Cal AD 1680 to 1690, Cal AD 1730, Cal 1810, Cal AD 1920 to 1930 and post AD 1950.

3. Results did not rule out human and laboratory (chemical) contamination which directly or indirectly influenced the results of the analyses. Special pretreatment procedure was suggested to possibly validate the current results.

4. Analyses of samples indicated that samples came from the same tree. Beta-316804 (The Wooden Cross) is a little older than Beta-316805 (Christ’s Image).

VII. Conclusions:

Based on the findings of the study, the following conclusions are drawn:

1. Results of the study revealed the proximity of the radiocarbon dating analyses to the traditional accounts of the people of Lubao, Pampanga. Considering the highly sensitive nature of analytical chemistry apparatuses, the time ranges (ages) drawn from the chemical analyses were closely proximate to the oral history accounts of the place. Notwithstanding, the errors on probability and contamination are important considerations which must be accounted as regards imperfect results of the analyses.
2. The results revealed the antiquity of the Crucifix (Cross and Image of Christ). The results predicate the customary and traditional social and religious norms of the people as regards their reverence and devotion to the Crucifix even in this contemporary milieu.
3. Results of the analyses were limited only to the perceived period when the Crucifix arrived in Lubao, Pampanga. It did not include the actual age of the tree when it was cut down or harvested from its original abode. It did not also include the condition of the Cross and Christ’s Image after they were rediscovered by some residents after its long period of concealment in the ground.

VIII. Recommendations

The following recommendations are derived from the conclusions:

1. To further bolster the result of the study, the proposed special treatment for the remaining wood samples offered by the radiocarbon dating agency must be availed to obtain a new perspective with regard the radiocarbon age of the sample.
2. The Archdiocese of San Fernando, Pampanga and National Commission on Culture and Arts should support the preservation of the Crucifix of the Holy Cross because of ecclesiastical and cultural significance.
3. The people of Lubao, Pampanga must be proud of the history and heritage of the Crucifix because of the glory that it has contributed to the nation. Its impact can contribute to the fertilization of spirituality and tourism.
4. The history of the Crucifix should be reintroduced and reinvigorated through book writings and construction of museum to reverberate its place in church history.
5. The Crucifix should be given due homage and historical recognition by the National Historical Commission of the Philippines.

IX. Documentation

apopampanga1
The Image of Apo Sto Cristo de Lubao

apopampanga2
The Team

chemical6
Wood sample taken from the wooden Cross (Beta 316804)

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Wood sample taken from Christ’s Image (Beta 316805)

Web Design by Engr. Mark Jason V. Sicat
Photo Credit: Sam C. Nicdao

8 thoughts on “CARBON DATING THE IMAGE OF APO STO. CRISTO DE LUBAO

  1. Maulaga yang bage ing megauang “carbon dating “, uling metung iang magpatibe keng dati mung kuentu da reng mangatua kanita . Maragul iang saup ini kareng susunud pang pamanialiksik emu keng kasaysayan na ning kekatamung patron “Apo Sto Cristo” nune pati na ing kekatamung lugal ampo reng memalen.

  2. Wow Sir Rodrigo, nakakamangha naman po ang Research niyo. I am proud of you sir… Keep it up. Thanks for giving us added inspiration in life. From: Rosendo “Jun” Bernabe, Jr., student in MAEd

  3. wow!!!ninong i enjoyed reading your articles…!!! sobrang proud me for you and ninang!!! worth it to be awarded INTERNATIONAL!!! God bless po…: ) grace

  4. sir, maliari ku pung abalu ing impormasyun tungkul king carbon dating ning apo sto. Cristo? Atin ke munaman pung imahen a matwa base keng istoria, dadala repa reng recolletos canita, eku pu makasigurado nung yapin pa ini, o inalilan dane, buri kea naman pu sanang pasuri

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