Direct dating of plaster and mortar using AMS radiocarbon: a pilot project from Khirbet Qana, Israel. (Method).

Direct dating of plaster and mortar using AMS radiocarbon: a pilot project from Khirbet Qana, Israel. (Method). Introduction Although radiocarbon dating has been utilised to date importantartefacts such as the Dead Sea Scrolls (Jull et al. 1995),archaeologists working on historic-period sites in the Near Eastgenerally rely, on techniques such as ceramic typologies, numismatic nu��mis��mat��ic?adj.1. Of or relating to coins or currency.2. Of or relating to numismatics.[French numismatique, from Late Latin numisma, numismat-, dating, diagnostic architectural elements, and in situ In place. When something is "in situ," it is in its original location. inscriptions forage determinations of structures and archaeological strata. In certaincircumstances, these techniques can assign ages to a feature for lesscost than [sup.14]C dating and with greater precision. However, datingby architectural forms and inscriptions is typically dependent onmonumental architecture, which is not always present. Ceramics and coinsonly provide accurate ages when they are sealed within primary contextsand are sufficiently abundant to narrow the age range of ceramic vesseltypes and coin assemblages. Additionally, many coins were circulatedwell beyond their age of minting, leading to age assessments that aretoo old. Radiocarbon dating therefore has a potential value,particularly if it can be applied to primary material in buildings. Khirbet Qana is a prime example of a site where traditional datingtechniques are not adequate. It contains few diagnostic architecturalelements and is composed of features and structures cut into or foundedon bedrock. There are few intact strata containing abundant coins orceramics of similar age. Instead there are many thin, heavily disturbedstratigraphic stra��tig��ra��phy?n.The study of rock strata, especially the distribution, deposition, and age of sedimentary rocks.strat horizons that contain ceramic assemblages of mixed ages.As a result of these limitations, it was unknown whether some structuresat Khirbet Qana were Roman (63 BC-330 AD) or Byzantine (363-640 AD) inage, and in other locations it was unclear whether features were lateArab/Crusader (1099-1291 AD) or modern (19th or 20th centuries). In order to refine the chronology of Khirbet Qana and assess thepotential of using accelerator mass spectrometry accelerator mass spectrometryn.Mass spectroscopy in which a particle accelerator is used to disassociate molecules, ionize atoms, and accelerate the ions. (AMS AMS - Andrew Message System ) radiocarbondating at Near Eastern archaeological sites, we radiocarbon-datedfourteen samples of organic matter. Thirteen of these samples wereorganic fragments sealed within in situ mortar and plaster, and onesample was of charcoal embedded within an uncemented floor. Althoughthere has been some work with [sup.14]C dating of organic materialwithin mortars (Kedar and Mook mook?n. SlangAn insignificant or contemptible person.[Probably alteration of moke.] 1978; Berger 1992), this is the firststudy to use AMS [sup.14]C to systematically date organic materialencased en��case?tr.v. en��cased, en��cas��ing, en��cas��esTo enclose in or as if in a case.en��casement n. in mortar or plaster to identify multiple phases ofconstruction. The study area Khirbet Qana is situated in the lower Galilee The Lower Galilee (Hebrew: הגליל התחתון‎ hagalil hatachton), is a region within the North District of Israel. region of Israel,within the Bet Netofa Valley (Figure 1). Excavations and an extensivesite survey began in 1997 under the direction of Douglas R. Edwards ofthe University of Puget Sound The University of Puget Sound (often called UPS or just Puget Sound) is a private liberal arts college located in the North End of Tacoma, Washington, in the United States. . Between 1997 and 2001, surface surveysand excavation at Khirbet Qana identified material evidence from theNeolithic through modern periods (6000 BC-19th century A.D). The mostextensive occupation of the site, based on architectural and materialremains, was during the Roman and Byzantine periods (Table 1). [FIGURE 1 OMITTED] Methods Organic inclusions in plaster and mortar were collected fromseveral areas of the site to address specific research questions.Samples were collected from two of the main excavation areas, aChristian cave shrine, thought to be Crusader in age, and a large publicstructure, possibly a Byzantine-period synagogue. Samples were alsocollected from a thick (~ 1m) vaulted wall exposed at the surface toidentify its age, from plaster layers within a possible mikvah (Jewishritual bath) to determine its age and whether it had multiple phases ofconstruction, and from an exposed plastered area (possibly industrial)founded on bedrock. Organic matter was only collected from in situ plaster and mortar(Figure 2). When there was an abundance of organic material within theplaster/mortar, between 100-500g of plaster was collected. In caseswhere there were few organics within the plaster/mortar, the materialwas hand picked in the field to isolate and collect occasional organicfragments. Samples were then chemically pre-treated, combusted,cryogenically purified, and made into graphite targets, which wereprocessed at the NSF NSF - National Science Foundation Arizona AMS Facility (see endnote See footnote. on processing). [FIGURE 2 OMITTED] Accuracy of [sup.14]C dating Three factors determine the accuracy of a radiocarbon age: 1) theintegrity of the sample being dated (i.e. are there any factors that maycause the sample to yield ages that are either too young or too old?),2) the precision and accuracy of the laboratory analysis, and 3) theconversion of the radiocarbon age to an age in calendar years. Here webriefly discuss the possible influences on the accuracy of our AMS[sup.14]C age determinations. The possible sources of error associated with samples commonly usedfor radiocarbon dating include, but are not limited to, contamination ofsecondary organic material such as roots or humic hu��mic?adj.Of, relating to, or derived from humus.Adj. 1. humic - of or relating to or derived from humus; "humic acid" acids (productsresulting from the decomposition of organic material), the mixture oforganics within a sedimentary matrix and the use or reuse of old wood.The "old wood" problem can result from either the use of woodthat has remained on the ground for long periods of time, a commonfeature of arid environments, or due to the reuse of woodenarchitectural elements (e.g. Liphschitz et al. 1997). Organic samples from Khirbet Qana should provide reliable [sup.14]Cages for a variety of reasons. First, the inclusion of organic materialwithin mortar/plaster ensures that the samples cannot post-date theplastering of the building. Furthermore, it is doubtful that the organicsamples significantly pre-date the plaster because most samples arecomposed of numerous, small organic pieces from several individualplants. In cases in which we dated only one wood fragment, the old woodproblem is possible, but unlikely because of the small size of theorganic material. We identified several sources of secondary organicmatter in the field and in the lab that could cause samples to yieldages that are too young, including: 1) small rootlets, which infiltratedthrough fractures in the plaster, 2) lichen lichen(lī`kən), usually slow-growing organism of simple structure, composed of fungi (see Fungi) and photosynthetic green algae or cyanobacteria living together in a symbiotic relationship and resulting in a structure that resembles neither on plaster and bedrock thatis exposed at the surface, 3) moss and algae algae(ăl`jē)[plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that on plaster within cisterns,and 4) insect faecal fae��cal?adj. Chiefly BritishVariant of fecal.Adj. 1. faecal - of or relating to feces; "fecal matter"fecal pellets (found in one sample). To avoid thesepotential problems, we did not sample in any area that contained moss,lichen, or algae. We sampled dry areas of plaster around the entrance of cisterns andother structures that collect water to avoid moss and algae. Rootletswere easily observable in the lab and were avoided. One sample ofplaster that contained insect faecal pellets did not contain any organicmatter, and therefore could not be dated. A significant advantage of AMS radiocarbon dating is the highprecision capable even on very small samples (0.5 mg C). For the agerange of our samples in this study, between ~2000 to 1000 years BP, theanalytical precision of the accelerator mass spectrometer spectrometerDevice for detecting and analyzing wavelengths of electromagnetic radiation, commonly used for molecular spectroscopy; more broadly, any of various instruments in which an emission (as of electromagnetic radiation or particles) is spread out according to some isapproximately [+ or -] 45 [sup.14]C years for one standard deviation(1[sigma]). Multiple measurements (three to five) of the same sample(termed high-precision analyses), however, can reduce the standarddeviation to roughly [+ or -] 30 years BP by statistically averaging theradiocarbon measurements (Ward and Wilson 1978). Radiocarbon age determinations were calibrated to calendar yearsusing CALIB 4.3 (INTCAL 98 dataset; Method A; Stuiver and Reimer 1993;Stuiver et al. 1998). Radiocarbon ages need to be calibrated because theproduction of [sup.14]C in the upper atmosphere is not constant, and theresidence time of [sup.14]C[O.sub.2] in reservoirs such as the oceansalso is variable (Jull 1998). Results and assessments: humic acid Noun 1. humic acid - a dark brown humic substance that is soluble in water only at pH values greater than 2; "the half-life of humic acid is measured in centuries"humic substance - an organic residue of decaying organic matter dates In this study 1[sigma] calibrated age ranges (68% probability) for[sup.14]C age determinations spanned from a minimum of 35 years to amaximum of 183 years, with an average of 107 years. Calibrated ageranges for 2[sigma] (95% probability) spanned from 143 years to 262years, with an average of 207 years. All radiocarbon ages are presentedin [sup.14]C years and 2[sigma] calibrated age ranges (Table 2). Roughly half of our age determinations, all those that came fromgrasses or small organic samples that completely dissolved onpre-treatment with NaOH, were on the humic acid (or humate) fraction ofour samples. Although humic acid fractions can yield ages that are tooyoung due to the addition of younger organic acids from soilstransported via ground water, other studies have found the humicfraction to yield reliable ages (Quade et al. 1998; Rech et al. 2002).However, acceptable age ranges for [sup.14]C analyses in historicalarchaeology Historical archaeology is a branch of archaeology that concerns itself with "historical" societies, i.e. those that had systems of writing. It is often distinguished from prehistoric archaeology which studies societies with no writing. are much narrower than in Quaternary Geology Quaternary geology is the part of geology that is concerned with the study of the Quaternary, the youngest geological period. Since most of our landscape was formed during this time, that also includes the ice age, it has a strong relationship with geomorphology. . To test thereliability of dating the humic acid fraction at Khirbet Qana we datedtwo matched pairs of the insoluble acid residue (A fraction) and humicacids (B fraction). Matched pairs of humic acid and acid residue fractions weredetermined for an olive pit incorporated in plaster (sample CR-16) and acomposite sample of small charcoal fragments (sample CR-22) incorporatedin a compacted, but uncemented, floor. If secondary humic acids wereincorporated in the material selected, we would expect significantdiscrepancies between the ages of the two fractions. Sample CR-22 isfrom the bottom of a cave, which receives significant amounts ofmoisture, and thus represents a worst-case scenario worst-case scenarion → Schlimmstfallszenario ntfor possiblesecondary contamination by humic acids transported by ground water. TheA and B fractions of CR-16 are within 2[sigma], with ages of 1910 [+ or-] 35 BP and 2015 [+ or -] 45 BP, respectively (Table 2). The A and Bfractions of CR-22 are also within 2[sigma], with ages of 1570 [+ or -]20 BP and 1655 [+ or -] 35 BP, respectively. These results demonstratethat [sup.14]C age determinations on the humic acid fractions of samplesare reliable. Results--determining sequence The high precision possible with AMS allowed its application toresolve questions of sequence. The cave shrine at Khirbet Qana issituated within a limestone cave and consists of an altar adorned withchiselled crosses and several layers of plaster on the cave walls andceilings. Excavation of the cave deposits revealed three successivefloors representing different phases of occupation (Figure 3).Radiocarbon ages from the plaster floors and other features of the caveprovide evidence for the use and modification of this area fromapproximately the fifth to twelfth centuries. The earliest use of thiscave corresponds to the lowest floor (CR-22) and altar (CR-20B), whichdate to the fifth or sixth century, and possibly the first half of theseventh century for the altar. High-resolution AMS [sup.14]C ages wereobtained for both the acid residue (CR-22A) and humic acid (CR-22B)fraction of charcoal in the lowest floor. CR-22A returned a date of425-556 cal AD (see Table 2 for the full data) and CR-22B a date of261-527 cal AD. Organics within mortar underlying the wall and altarplaster (CR-20B) returned a date of 415-654 cal AD, suggesting that thealtar was first associated with the lowest floor. [FIGURE 3 OMITTED] Charcoal samples incorporated within the middle floor (CR-18A)returned a date of 658-801 cal AD. Charcoal samples embedded in theupper floor (CR-17A) yielded a date of 1024-1217 cal AD. Organicsincluded within the mortar cementing the stone bench that rests on topof the upper floor (CR-21 B) yielded a date of 984-1160 cal AD,indicating that the construction of the stone bench does notsignificantly post-date the upper floor, but was likely constructed inconjunction with the upper floor. In this context, the radiocarbon datesoffered a better account of the structural sequence than could have beenobtained from stratigraphy stratigraphy,branch of geology specifically concerned with the arrangement of layered rocks (see stratification). Stratigraphy is based on the law of superposition, which states that in a normal sequence of rock layers the youngest is on top and the oldest on the or the ceramic assemblage. Possible synagogue The possible synagogue structure contains numerous plasteredbenches and other architectural elements that suggest it was used as agathering place. Three AMS [sup.14]C age determinations were made onorganics (CR-5, CR-8, CR-12) incorporated in plaster or mortar from thisstructure and indicate a Roman and subsequent late Byzantine/early Arabphase of construction (Figure 4). Organics from the lower wall plaster(CR-8A) yielded a date of 4-236 cal AD, suggesting that this wall wasinitially constructed during the early to middle Roman period. Organicsfrom the interior plaster floor (CR-12B) yielded a date of 128-382 calAD, indicating that this floor is also Roman in age and in phase withthe age of the wall (Figure 4). Organics in the upper plaster floor(CR-5A), associated with an entranceway to this building, returned adate of 602-763 cal AD and indicate a late Byzantine/early Arab additionto the building. A comparison between the [sup.14]C and the ceramicevidence also showed that in this area greater age control was affordedby radiocarbon dating. Subsequent excavation of the wall foundation(Figure 4) revealed strata containing only Roman pottery, supporting theRoman age of this feature. [FIGURE 4 OMITTED] Spot dating of other exposed features Organic samples included in plaster from three other features atKhirbet Qana were selected for AMS [sup.14]C dating to test thepotential of this technique as a survey tool and its effectiveness fordating structures founded on bedrock. A large structure with a thickarched wall is partially exposed in the lower village of Qana. Thisstructure has not been excavated and it was unknown whether it isByzantine, Arab, or modern (18th--19th Century) in age. However,organics within mortar from the arched wall (CR-30A), yielded a date of897-1159 cal AD, indicating a Crusader/late Arab age. Organic material within plaster from two plastered bedrock featureswas also selected for radiocarbon dating to test the potentialapplication of this technique. Organics within plaster (CR-2B) from asmall industrial installation, founded on bedrock and lacking overlying overlyingsuffocation of piglets by the sow. The piglets may be weak from illness or malnutrition, the sow may be clumsy or ill, the pen may be inadequate in size or poorly designed so that piglets cannot escape. sediment (Figure 5), yielded a date of 15 cal BC-239 cal AD indicatingan early to middle Roman age. Organics incorporated within two distinctlayers of plaster, each 1 cm thick, from a possible Mikvah were dated todetermine the age of this feature and identify if these plaster layersrepresented significantly different occupational phases. The acidresidue fraction of an olive pit (CR-16A) incorporated within the innerlayer of plaster yielded a high-resolution date of 23-214 cal AD. Thehumic acid fraction from this olive pit (CR-16B) returned an age of 160cal BC--78 cal AD. Organics from the outer layer of plaster (CR-15B)yielded a date of 30-239 cal AD. These results indicate that phases ofplastering of this structure occurred during the early to middle Romanperiod. [FIGURE 5 OMITTED] Conclusions The ability to date small (1-3mg) organic samples included withinplaster and mortar, with an age resolution of ca. 100 (1[sigma]) to ca.200 (2[sigma]) years, has broad implications for both historical NearEastern Archaeology Near Eastern Archaeology (sometimes known as Middle Eastern archaeology) is a regional branch of the wider, global discipline of Archaeology. It refers generally to the excavation and study of artifacts and material culture of the Near East from antiquity to the recent past. or any archaeological culture In addition to its usual meaning in social science, in archaeology, the term is also used in reference to several related concepts unique to the discipline. Archaeological cultureThis article or section may contain original research or unverified claims. that made use ofmortar and plaster. At the site of Khirbet Qana this technique (i)afforded higher age resolution than provided by ceramic typologies attwo stratigraphically bound locations, (ii) provided ages for plasteredbedrock features that could not have been dated by any other means, and(iii) was successfully used as a survey tool to determine the age ofpartially exposed structures, without destroying the archaeologicalrecord The archaeological record is a term used in archaeology to denote all archaeological evidence, including the physical remains of past human activities which archaeologists seek out and record in an attempt to analyze and reconstruct the past. through excavation. In Near Eastern Archaeology, AMS [sup.14]C dating of organics inplaster/mortar should nevertheless be used in association with ceramics,coins, and architectural evidence to provide the strongest possible agecontrol. The precision that can be added by AMS [sup.14]C at a site willdepend on the quality of the stratigraphic, numismatic and ceramicsequence already present, the abundance of organic material withinplaster and mortar at the site, and, due to the nonlinear calibration of[sup.14]C, the age of the material to be dated. Perhaps the greatest potential of the technique is its role insurvey and evaluation. The age of partially exposed structures, orstructures wholly cleared but unpublished, can be estimated without toomuch additional damage and at relatively low cost, and this in turnallows informed decisions to be obtained for the design of programmes ofresearch and conservation. Endnote on processing Organic samples were hand picked to concentrate organic materialand separate any secondary organics, such as rootlets. Samples wereplaced in hot (70[degrees]C) 2 M HCI (Human Computer Interaction) Refers to the design and implementation of computer systems that people interact with. It includes desktop systems as well as embedded systems in all kinds of devices. to remove carbonates, rinsedseveral times with deionized water Deionized water (DI water or de-ionized water; also spelled deionised water, see spelling differences) is water that lacks ions, such as cations from sodium, calcium, iron, copper and anions such as chloride and bromide. , placed in hot NaOH to remove humicacids (weathering products of organic matter that can result inerroneous in [sup.14]C ages) and rinsed again in deionized water.Samples were combusted with CuO and Ag and the C[O.sub.2] gas wascryogenically purified on a vacuum line. Samples were converted tographite by standard methods and submitted to the University ofArizona-NSF Radiocarbon lab. Two line blanks run with the samplescontained <0.0027 and <0.0031 fraction modern [sup.14]C, thenormal range for line blanks. [delta][sup.13]C analyses were run onseparate C[O.sub.2] gas aliquots on a Finnigan Delta S massspectrometer.Table 1. Chronology of recent archaeological periods in GalileePeriod Age RangeCrusader/Late Arab 1099-1291 ADArab 640-1099 ADLate Byzantine 451-640 ADEarly Byzantine 363-451 ADLate Roman 250-363 ADMiddle Roman 135-250 ADEarly Roman 63 BC-135 ADHellenistic 332-63BCTable 2. AMS--[sup.14]C analyses and calibrated agesSample * Age [sup.14]CNumber Lab Number Material yrs[section] B.P.CR-2B AA42272 Organics 1900CR-5A AA41830 Organics 1375CR-8A AA41831 Organics 1900CR-12B AA42273 Organics 1785CR-15B AA42274 Organics 1880CR-16A AA41832 Run1 Olive pit 1910 Run 2 1905 Run 3 1915 Weighted Average 1910CR-16B AA41833 Organics 2015CR-17A AA41834 Run 1 Charcoal 910 Run 2 980 Run 3 975 Weighted Average 960CR-18A AA41835 Charcoal 1295CR-20B AA42275 Organics 1520CR-21B AA42276 Organics 985CR-22A AA41836 Run 1 Charcoal 1575 Run 2 1545 Run 3 1590 Weighted Average 1570CR-22B AA41837 Run 1 Charcoal 1565 Run 2 1658 Run 3 1630 Weighted Average 1655CR-30A AA41838 Organics 1015Sample * Stan. CalibratedNumber Lab Number Dev. 1[sigma] Age[dagger] (1[sigma])CR-2B AA42272 50 34-133 cal ADCR-5A AA41830 45 642-677 cal ADCR-8A AA41831 45 65-132 cal ADCR-12B AA42273 45 145-323 cal ADCR-15B AA42274 40 78-211 cal ADCR-16A AA41832 Run1 45 32-130 cal AD Run 2 40 65-130 cal AD Run 3 35 33-128 cal AD Weighted Average 35 35-129 cal ADCR-16B AA41833 45 cal BC-50 cal ADCR-17A AA41834 Run 1 35 1038-1137 cal AD Run 2 40 1018-1152 cal AD Run 3 35 1019-1152 cal AD Weighted Average 35 1038-1187 cal ADCR-18A AA41835 40 667-774 cal ADCR-20B AA42275 60 435-618 cal ADCR-21B AA42276 40 104-1150 cal ADCR-22A AA41836 Run 1 45 424-540 cal AD Run 2 40 433-595 cal AD Run 3 35 422-596 cal AD Weighted Average 20 432-557 cal ADCR-22B AA41837 Run 1 60 423-595 cal AD Run 2 35 344-425 cal AD Run 3 35 400-433 cal AD Weighted Average 35 358-426 ADCR-30A AA41838 55 984-1034 ADSample * CalibratedNumber Lab Number Age (2[sigma])CR-2B AA42272 15 cal BC-239 cal ADCR-5A AA41830 602-763 cal ADCR-8A AA41831 4-236 cal ADCR-12B AA42273 128-382 cal ADCR-15B AA42274 30-239 cal ADCR-16A AA41832 Run1 15 cal BC-230 cal AD Run 2 5-225 cal AD Run 3 5-210 cal AD Weighted Average 23-214 cal ADCR-16B AA41833 160 cal BC-78 cal ADCR-17A AA41834 Run 1 1024-1217 cal AD Run 2 988-1160 cal AD Run 3 997-1160 cal AD Weighted Average 1024-1217 cal ADCR-18A AA41835 658-801 cal ADCR-20B AA42275 415-654 cal ADCR-21B AA42276 984-1160 cal ADCR-22A AA41836 Run 1 398-600 cal AD Run 2 421-619 cal AD Run 3 401-558 cal AD Weighted Average 425-556 cal ADCR-22B AA41837 Run 1 363-638 cal AD Run 2 261-436 cal AD Run 3 342-536 cal AD Weighted Average 261-527 ADCR-30A AA41838 897-1159 AD* Letter `A' at the end of the sample number indicated a radiocarbonage determination on the acid residue fraction of the organicmaterial, whereas `B' signifies an age determination on the humicacid fraction.[section] Radiocarbon ages and standard deviations rounded to nearestfive-year interval.[dagger] Calibrated age ranges were determined by using the interceptmethod (Method A) in CALIB rev.4.3, 2000. Acknowledgements Radiocarbon analyses were funded by NSF grant EAR97-30699. Fundingfor field expenditures for J.A.R. and A.A.F. was provided by the Qana ofthe Galilee Galilee(găl`ĭlē), region, N Israel, roughly the portion north of the plain of Esdraelon. Galilee was the chief scene of the ministry of Jesus. Excavations. Comments by Jeffrey S. Pigati and P. JeffreyBrantingham greatly improved this manuscript. References BERGER, R. 1992. [sup.14]C dating mortar in Ireland, Radiocarbon34: 880-89. JULL, A. J. T., D. J. DONAHUE, M. BROSHI & E. TOV TOV Ten Opzichte Van (Dutch: with regard to)TOV Tone of Voice (linguistics, branding)TOV Treaty of Versailles (treaty ending WWI)TOV Temple of Veeshan . 1995.Radiocarbon dating of scrolls and linen fragments from the JudeanDesert, Radiocarbon 37: 11-19. JULL, A. J. T. 1998. Accelerator radiocarbon dating of art,textiles, and artefacts, Nuclear News June 1998: 30-38. KEDAR, B.Z. & W.G. MOOK. 1978. 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INTCAL98 radiocarbon age calibration, Radiocarbon 40: 1041-83. WARD, G.K. & S.R. WILSON. 1978. Procedures for comparing andcombining radiocarbon age determinations: a critique, Archaeometry 20:19-30. Jason A. Rech (1) *, Alysia A. Fischer (2), Douglas R. Edwards (3),A.J. Timothy Jull (4) (1) Geology Department, Miami University Miami University,main campus at Oxford, Ohio; coeducational; state supported; chartered 1809, opened 1824. The library has extensive collections in literature and American history, including the William Holmes McGuffey Library and Museum and the Edgar W. , Oxford, OH 45056, USA(*rechja@muohio.edu). 2) Anthropology and Sociology Program, CentreCollege, Danville, KY40422, USA. 3) Professor of Archaeology andReligion, University of Puget Sound, Tacoma WA 98416, USA. 4) NSFArizona AMS Facility and Department of Geosciences, University ofArizona (body, education) University of Arizona - The University was founded in 1885 as a Land Grant institution with a three-fold mission of teaching, research and public service. , Tucson, AZ 85721 Received 7 February 2002; Accepted 19 September 2002; Revised 26January 2003.