Tredoux, M.Holmes, P. J.Douglas, Rodney Malcolm2015-09-042015-09-042009-04http://hdl.handle.net/11660/1168English: The Florisbad Quaternary Research Station and archaeozoological site is located 45 km north-west of Bloemfontein, Free State Province, South Africa (28° 46` 05.4”S, 26° 04` 10.7”E), and is sited around a series of highly saline, warm water spring vents. The site is partially covered by a large sand dune. The site is significant for three important reasons. Firstly, the discovery of the Florisbad skull (Homo helmei) in 1932 by Prof. T. Dreyer, secondly, a collection of faunal fossil remains representing at least 31 taxa, including extinct and extant species, and referred to as the Old Collection and, thirdly, a Middle Stone Age (MSA) human occupation horizon representing a temporary butchering site with evidence of a hearth, butchering tools, and faunal fossil remains. Spring- and excavation pit water samples were taken and analysed in 1988 during a high rainfall period, and in 1999 during an average rainfall period. In relation to the spring water, the results show that the total dissolved solids (TDS) of the excavation pit water were, in relation to the spring water, higher during the high rainfall period and lower during the average rainfall period. This was contrary to the norm, where it is expected that high rainfall periods should produce a decrease in TDS due to a dilution effect. The TDS of the spring-water remained stable throughout both high and average rainfall periods. Further analysis showed considerable TDS increases between the excavation pit waters, and between the pit waters and the spring-water. It is concluded that the pit waters were not directly related to the spring water and that the two water bodies were separate entities with the pit water being recognized as groundwater. An analysis of rainfall in relation to the TDS of the spring- and groundwater indicated that short-term rainfall affected the quality of the groundwater, but not the quality of the spring-water, while long-term rainfall had little effect on the quality of the spring-water. The question arose as to why the TDS of the groundwater was so much higher than that of the spring-water, and what factors were causing these differences? Organic-clay (peat) samples from the walls of the excavation pits as well as the walls of the open excavation area were analysed. The results of the analyses, and an examination of the stratigraphy, strongly suggested that minerals had accumulated in the organic-clay layers due to organic matter having a similar colloidal organization to that of clay, with the ability to adsorb large quantities of minerals on their outer surfaces. A comparison of the groundwater and organic-clay analyses results showed that the TDS of the decomposed Peat II organic-clay layer was considerably higher than that of the groundwater, with the same being true for the far less decomposed Peat IV organic-clay layer. By analysing and combing the water and organic-clay layer results with the many factors, mechanisms, and processes involved, it is concluded that the salinization of the organic-clay layers, and the flushing of ions from the organic-clay layers by percolating water during rainfall periods, is responsible for the increased mineralization of the groundwater. Other factors, mechanisms, and processes, such as rainfall, aeolian deposition, evaporation, capillarity, wind, temperature, matrix-suction, pH, Eh, PCO2, PO2, DOC, and biomineralization, all of which support the accumulation of free salts in a semi-arid environment such as Florisbad, were also investigated. Of primary importance was the question as to whether the spring-water was actually responsible for fossilization of the faunal remains, and could fossilization have taken place within the environs of the spring vents, or in the spring vents themselves? Previous research has suggested that the spring-water was calcium-carbonate rich, with evidence of calcium-carbonate deposition further suggesting that faunal remains of the Old Collection must have been in contact with the spring-water in spring vents for some time. An analysis of the spring-water analysed over the past 84 years indicated that there had never been sufficient Ca (under-saturation) in the spring-water for fossilization to occur, and this is confirmed by the current analyses. The contemporary lack of Ca in the springwater, combined with other environmental factors within the environs of spring vents, such as the lack of organic matter and clay, combined with a high Eh environment, also strongly indicated that, historically, fossilization could not have taken place within the environs of the springs. Contrary to earlier hypotheses, it is concluded that the spring water and spring flow would directly assist in the de-mineralization of faunal remains. A detailed investigation of the site, along with an analysis of the stratigraphy and sedimentation, revealed that previous theories on the formation of the site did not sufficiently accommodate the current stratigraphy in the context of the organic-clay layers, the salinization process, and fossilization. From this deduction all the existing and pre-existing evidence was revisited in an attempt to provide a hypothesis which would accommodate the existing morphology of the site, sedimentation, and fossilization. It is hypothesised that the spring site formed around a large drainage-impeded pan which was largely covered by a sand dune that had migrated from the area of the extensive salt pan to the north and north-west (Soutpan). The arms of the dune eventually came to rest up against the windward slope of a dune belt located just south of the spring site, and a dam began to form. High rainfall periods produced organic-clay layers, while sandy layers were produced during drier windy periods. This led to the formation of alternating horizontal layers of organic-clay and sand, eventually building up to almost the top of the sand dune on the leeward face. When the water level in the dam reached the top of the arms of the sand dune, it broke through the eastern arm. The dam water and sediments then evacuated the dam in a flash flood. This flash flood eroded the area to the east of the site to such an extent that the drainage was diverted, and a wide flat-bottomed vlei was formed where much of the dam sediments were deposited. This hypothesis provides an alternative for the formation of the spring site, accommodating all aspects of sedimentation, salinization, and fossilization. The dating of the Florisbad deposits and fossils has been subject to an ongoing debate since the first 14C dating was carried out in 1954. The ages and depths of recently published profiles did not appear to correspond to the assumption of greater compaction with depth and time. In an attempt to resolve this issue, linear, exponential, and logarithmic mathematical trend lines were then experimentally applied to the published profiles of electron spin resonance (ESR) and optical stimulated luminescence (OSL) dates in order to test the theory of compaction, and to validate the results. The hypothetical effect of manipulating ages on trend lines was also tested. A discussion on some possible shortfalls regarding the dating methods used is undertaken. A best logarithmic fit to data was obtained by holding the ESR Middle Stone Age Human Occupation Horizon (MSA) age at 127 ka, and advancing the lower deposit age from 250 ka to 420 ka. The next best fit to data occurred by regressing the ESR MSA age from 127 ka to 78 ka, and holding the lower deposit age at 250 ka. The application of exponential and linear trend lines produced poor fits to data. A suggested compaction trend line was also introduced which produced an ESR MSA age of 75 ka and a lower deposit age of 384 ka. In the final analysis, trend line results suggested an MSA age of 92 ±12 kyr and a basal deposit age of 400 ±20 ka. The logarithmic and suggested compaction trend line ages for the lower deposits both produced ages similar to the suggested Florisain – Cornelian faunal boundary of c. 400 ka. The exercise confirmed that the ages in the published profiles were disjunct and that this disjunction may be related to a number of different physical forces.Afrikaans: Die Florisbad Kwaternêre Navorsingstasie en argeosoölogiese terrein is 45 km noordwes van Bloemfontein, Vrystaat Provinsie, Suid-Afrika geleë (28° 46` 05.4”S, 26° 04` 10.7”E) langs ‘n reeks uiters sout- en swaelryke warmwater fonteine. Die terrein is gedeeltelik bedek deur ‘n groot sandduin. Die terrein is betekenisvol vanwee drie belangrike redes: Eerstens die ontdekking van die Florisbad-skedel deur prof. T. Dreyer in 1932, tweedens `n versameling van dierlike fossieloorblysfsels wat ten minste 31 taksa van uitgestorwe en bestaande spesies verteenwoordig (bekend as die Ou Versameling), en derdens ‘n menslike bewoningshorison uit die middel-Steentydperk (MST) wat ‘n tydelike slagplaas, tekens van ‘n vuurherd, slaggereedskap en dierlike fossieloorblyfsels toon. Monsters van die fonteinwater en sypelwater in die uitgrawings is in 1988 gedurende ‘n tydperk van hoë reënval, en in 1999 gedurende ‘n tydperk van gemiddelde reënval, geneem en ontleed. Die resultate dui aan dat die totale opgeloste vastestowwe (TOV) van die sypelwater in die uitgrawings, in vergelyking met dié van die fonteinwater, hoër was gedurende die nat periode en laer gedurende die gemiddelde reënvalperiode. Dit is teenstrydig met die norm wat sou verwag dat hoë reënvalperiodes ‘n afname in TOV sal oplewer as gevolg van ‘n verdunningseffek. Die TOV van die fonteinwater het stabiel gebly deur beide die hoë en gemiddelde reënvaltydperke. Verdere ontleding het ‘n aansienlike TOV toename tussen die sypelwater van verskillende uitgrawings en tussen die sypelwater en fonteinwater getoon. Die gevolgtrekking is dat sypelwater in uitgrawings nie direk verband hou met fonteinwater nie en dat die twee waterliggame aparte entiteite is waarvan die sypelwater as grondwater beskou kan word. ‘n Analise van reënval in verhouding tot die TOV van die fontein- en grondwater dui aan dat korttermyn reënval die kwaliteit van die grondwater beïnvloed maar nie dié van die fonteinwater nie. Langtermyn reënval het weinig invloed op die kwaliteit van fonteinwater. Die vraag het ontstaan waarom die TOV van die grondwater soveel hoër is as dié van die fonteinwater en watter faktore hierdie verskille veroorsaak. Organiese klei (veen) monsters van die kante van uitgrawings asook die kante van die oop uitgrawing is geanaliseer. Die resultate van die analises en ‘n ondersoek van die stratigrafie het sterk aanduidings getoon dat minerale in die organiese kleilae versamel het, as gevolg van die feit dat organiese materiaal dieselfde kolloïdale struktuur as klei het en die vermoë besit om groot hoeveelhede minerale in hulle buitenste lae te adsorbeer. ‘n Vergelyking tussen die resultate van die grondwater- en organiese klei analise het getoon dat die TOV van die ontbinde Veen II organiese kleilaag aansienlik hoër was as dié van die grondwater, terwyl dieselfde vir die veel minder ontbinde Veen IV organiese kleilaag geld. Deur die resultate van die water en organiese kleilaag te vergelyk met die baie faktore, meganismes en prosesse betrokke, word die gevolgtrekking gemaak dat versouting van die organiese kleilae en die loging van ione uit die organiese kleilae deur sypelwater gedurende reënval periodes, verantwoordelik is vir die toenemende mineralisasie van die grondwater. Ander faktore, meganismes en prosesse soos reënval, aeoliese neersetting, verdamping, kapillariteit, wind, temperatuur, matriks-suiging, pH, Eh, PCO2, PO2, DOC en biomineralisasie wat almal bydra tot die opeenhoping van vry soute in ‘n semi-ariede omgewing soos Florisbad, is ook ondersoek. Van primêre belang was die vraag of fonteinwater eintlik verantwoordelik was vir fossilering van die dierlike oorblyfsels en of fossilering in die omgewing van fonteine of in die fonteine self kon plaasvind. Vorige navorsing het daarop gedui dat fonteinwater kalsiumkarbonaatryk was, met aanduidings van kalsiumkarbonaat afsetting wat verder daarop dui dat dierlike oorblyfsels van die Ou Versameling vir ‘n geruime tyd in kontak met die fonteinwater in fonteinne moes gewees het. Wateranalise van die fonteinwater oor die afgelope 84 jaar het aangedui dat daar nog nooit voldoende Ca (onderversadiging) in die fonteinwater was vir fossilering om plaas te vind nie en dit word bevestig deur die huidige analise. Die hedendaagse gebrek aan Ca in die fonteinwater, in kombinasie met ander omgewingsfaktore in die omtrek van fonteine, soos die gebrek aan enige organiese materiaal of klei en ‘n hoë Eh omgewing, is ‘n sterk aanduiding dat fossielisering nie in die verlede in fonteine kon plaasgevind het nie. In teenstelling met vorige hipoteses word die gevolgtrekking gemaak dat fonteinvloei bydraend is tot die demineralisasie van dierlike oorblyfsels. ‘n Gedetailleerde ondersoek van die terrein, saam met ‘n analise van die stratigrafie en sedimentasie, het aan die lig gebring dat vorige teorieë oor die ontstaan van die terrein nie die huidige stratigrafie ten opsigte van die organiese kleilae, die versoutingsproses en fossilisering, genoegsaam in ag geneem het nie. Met hierdie afleiding in gedagte is al die bestaande en vooraf bestaande getuienis weer nagegaan in ‘n poging om met ‘n hipotese voor ‘n dag te kom wat die bestaande morfologie van die terrein, sedimentasie en fossilering sou kon akkommodeer. Daar word gehipoteseer dat die fontein gevorm het in die omgewing van‘n groot pan met beperkte dreinering. Hierdie pan was grootliks bedek deur ‘n sandduin, wat migreer het van die oorspronklike terrein in ‘n noord- en noordwestelike rigting (Soutpan). Die arms van die duin het uiteindelik tot ruste gekom teen die windkanthang van ‘n duingordel wat net suid van die terrein van die fontein geleë is en het ‘n dam gevorm. Hoë reënval periodes het organiese kleilae gevorm, terwyl sanderige lae gedurende droër winderige periodes gevorm is. Dit het gelei tot die vorming van afwisselnde horisontale lae van organiese klei en sand, wat uiteindelik tot amper by die kruin aan die lykant van die sandduin opgebou het. Die stygende watervlak het deur die oostelike arm van die sandduin gebreek en water en sediment in die dam is d.m.v. ‘n blitsvloed gedreineer. Hierdie blitsvloed het die area oos van die terrein tot so ‘n mate geërodeer dat die dreinering herlei is en ‘n wye vlei gevorm het waar baie van die sedimente van die dam gedeponeer is. Hierdie hipotese verskaf ‘n alternatiewe verklaring vir die vorming van die terrein om die fonteine en sluit alle aspekte van sedimentasie, versouting en fossilering in. Die ouderdom van die Florisbad afsettings en fossiele is sedert die eerste 14C ouderdomsbepaling gedoen in 1954, onderworpe aan ‘n voortgesette debat. Die ouderdomme en dieptes van onlangs gepubliseerde profiele het skynbaar nie ooreengestem met die aanname van hoër kompaksie met diepte en tyd. In ‘n poging om hierdie kwelvraag op te los, is lineêre, eksponensiële en logaritmiese wiskundige tendenskrommes op die gepubliseerde profiele van ESR en opties gestimuleerde luminessensie (OSL) ouderdomme gebruik om die teorie van kompaksie te toets en die resultate daarvan te bekragtig. Die hipotetiese effek van die manipulering van ouderdomme op tendenskrommes is ook getoets. Die moontlike tekortkominge van die dateringsmetodes wat gebruik is, word ook bespreek. ’n Beste logaritmiese datapassing is verkry deur die ESR Middel Steentydperk Menslike Bewoningshorison (MST) ouderdom van 127 ka konstant te hou en die laer afsettingsouderdom van 250 ka na 420 ka te verander. Die volgende beste datapassing is verkry deur die ESR MST ouderdom van 127 ka na 78 ka terug te skuif en die laer afsettingsouderdom op 250 ka konstant te hou. Die aanwending van eksponensiële en lineêre tendenskrommes het swak datapassings opgelewer. ‘n Voorgestelde kompaksietendenskromme is ook toegepas. Dit het ‘n ESR MST ouderdom van 75 ka en ‘n laer afsettingsouderdom van 384 ka opgelewer. In die finale analise het die tendenskromme resultate ‘n MST ouderdom van 92 ±12 ka en ‘n basale afsettingsouderdom van 400 ±20 ka voorgestel. Die logaritmiese en voorgestelde kompaksie tendenskromme ouderdomme vir die laer afsettings het beide ouderdomme opgelewer soortgelyk aan die voorgestelde Florisiaans – Corneliaanse fauna grens van c. 400 ka. Die oefening het bevestig dat die ouderdomme in die gepubliseerde profiele disjunk was en dat hierdie disjunksie verwant kan wees aan verskilende fisiese kragte.enThesis (Ph.D. (Geology and Geography))--University of the Free State, 2009Groundwater -- South Africa -- FlorisbadFossilizationHydrogeology -- South Africa -- FlorisbadGeology -- South Africa -- Free State -- FlorisbadFlorisbadArchaeozoological siteSpring-waterOrganic-clay layersSalinizationChemistryGeohydrologyDepositional environmentFormation of siteDatingThesisUniversity of the Free State