284 research outputs found
Coastal problems : geomorphology, ecology and society at coast/ Viles
No full textx, 350 hal.: ill, tab.; 25 cm
Ecosustainable and phytobased alternative methods for the conservation of biodeteriorated stone materials
No full textIl presente lavoro di tesi propone di sviluppare un metodo finalizzato al trattamento di materiali lapidei biocolonizzati, tramite l’impiego di sostanze chimiche di origine naturale (i.e. fitochimici), caratterizzati da un basso impatto ambientale, una bassa tossicità per l’uomo e che non compromettano lo stato conservativo dei beni culturali.
In questa prospettiva, sono state sfruttate le già note proprietà biocide di tre Oli Essenziali (EOs) già largamente studiati e impiegati in diversi ambiti, tra cui quello della conservazione dei beni culturali. Tali sostanze sono ottenute a partire da piante molto comuni della flora mediterranea, ed in particolare si tratta degli oli di Origanum vulgare, Thymus vulgaris e Clinopodium nepeta. Ogni olio essenziale ha una composizione chimica molto eterogenea, sebbene siano sempre presenti uno o due componenti chimici maggioritari, anche definiti Principi Attivi (APs), che ne definiscono il chemiotipo e sembrerebbero condizionarne l’azione biocida, sebbene non sia ancora stato sistematicamente dimostrato. In virtù di quanto detto, l’effetto biocida dei tre oli essenziali è stato confrontato con quello dei loro rispettivi principi attivi ovvero: carvacrolo per O. vulgare, timolo per T. vulgaris e pulegone per C. nepeta.
Per valutarne un possibile incremento dell’azione biocida, ogni olio è stato applicato singolarmente e in combinazione con gli altri due, in modo da creare diverse miscele contenenti rispettivamente, uno, due e tre composti, e lo stesso è stato fatto per i principi attivi. L’applicazione sulle superfici lapidee biocolonizzate ha previsto l’incapsulamento delle sostanze attive all’interno di una matrice idrogel (HG) di nuova formulazione, composta dalla miscela di sostanze polimeriche e tensioattivi, i cui più grandi vantaggi sono legati all’atossicità nella composizione chimica e alla capacità di formare un film omogeneo, pelabile, facile da rimuovere dalle superfici una volta asciutto. I composti sono stati testati su diversi biofilm presenti su substrati lapidei in granito e travertino. In particolare, le sperimentazioni hanno previsto l’applicazione su campioni di granito (in laboratorio) e su due superfici murarie, una in granito e una in travertino, esposte a diverse condizioni ambientali. Per la valutazione dell’azione biocida e pulente dei composti fitochimici, sono state effettuate misure non invasive di colore e di fluorescenza che potranno essere replicate anche sui beni culturali. Il sistema ottenuto dalla combinazione dell’idrogel e dei fitochimici (phyto-HG) ha mostrato buoni risultati per quanto riguarda l’azione pulente e biocida nei confronti di differenti biofilm, anche rispetto a quelle dimostrate da un sistema classicamente utilizzato per la pulitura meccanica dei beni culturali (spazzolatura) e di un comune biocida (Preventol® RI80).
Le prove sperimentali hanno messo in evidenza l’efficacia dei principi attivi i quali, possono essere considerati, nella maggior parte dei casi, più efficienti rispetto ai corrispondenti oli essenziali. Questo risultato è molto incoraggiante per le future sperimentazioni riguardanti lo sviluppo del metodo, che potrebbe prevedere l’impiego dei soli principi attivi per la realizzazione delle formulazioni biocide, con i notevoli vantaggi legati ai minori costi di produzione e alla possibilità di ridurre i limiti legati all’impossibilità di controllare le composizioni chimiche degli estratti naturali.
L’azione ottenuta dalla combinazione di più sostanze necessita ulteriori approfondimenti, in quanto sembrerebbe che la loro azione sia condizionata dalla sinergia che si ottiene da più sostanze nei confronti di specifici microorganismi presenti.
Il monitoraggio a medio e a breve termine effettuato sui campioni sperimentali ha evidenziato un’azione prolungata delle sostanze nel tempo. Sebbene questo non possa essere considerato sempre vantaggioso, in quanto ci si potrebbero aspettare delle reazioni secondarie che potrebbero verificarsi tra i residui e la matrice lapidea, è importante comunque sottolineare i vantaggi legati all’inibizione a lungo termine nei confronti di una possibile ricolonizzazione della superficie. Per queste ragioni, risulta importante analizzare più approfonditamente la stabilità dei fitochimici nel tempo, tramite l’osservazione di possibili modifiche delle proprietà chimiche ed estetiche dei materiali.The present PhD thesis aims to develop a valid strategy for the treatment of the biocolonization of stone materials, by employing natural chemical substances (i.e. phytochemicals) harmless towards ecosystems, human health, and cultural heritage materials. To achieve this goal, the well know biological properties of the Essential Oils (EOs) have been exploited, by employing three of these plant extracts that have already demonstrated inhibitory effects towards different microorganisms. These oils are obtained from Mediterranean plants of the Lamiaceae family, in particular: Origanum vulgare, Thymus vulgaris and Clinopodium nepeta. Each EO is characterized by the presence of one or two mayor chemical components, also defined Active Principles (APs). It seems that the biocidal action of each EO is established by the presence of specific APs, although this was not systematically proven. To demonstrate what has just been said, in this study, the effect of the EOs has been compared to the one of the respective APs, which are carvacrol for O. vulgare, thymol for T. vulgaris and pulegone for C. nepeta. Each EO has been applied alone and combined with the two others, in mixtures containing two and three EOs. The same process occurred with the APs. This was done to assess a possible empowerment of the biocidal action when more substances are combined. For their application on biodegraded stone surfaces, the phytochemicals were incorporated inside an innovative hydrogel (HG) matrix based on a mixture of polymeric substances and surfactants; whose main advantage is linked to its ability of forming a peelable layer when applied on surfaces. The compounds were tested on biofilms, colonizing granite and travertine surfaces. The experimentations were performed on granite samples and on two biocolonized walls, one in granite and the other in travertine. The biocidal and cleaning properties of the systems composed by the phytochemical substances and the hydrogel have been assessed through non-invasive colorimetric and fluorescence measurements. The phyto-HG systems demonstrated good cleaning and large spectrum biocidal properties against different biofilms, also compared to the ones of a commonly employed mechanical cleaning tool (brushing) and a common biocide (Preventol ® RI80).
The APs also showed their broad-spectrum biocidal action, which can be considered, in many cases, higher than the one of the respective EOs. This is an encouraging result, in sight of possible future developments of the method, that will provide the employment of the only APs for the creation of the formulations, with notable advantages linked to the reduction of the production costs and the possibility of reducing the limits linked to the impossibility of controlling the chemical composition of the natural extracts (i.e. the EOs).
The action of the combined substances compared to biofilms needs to be further analysed, because it seems that their action is strongly linked to the synergism occurring between two substances and the specific microorganisms present.
The short-term and medium-term monitoring carried out on the experimental samples evidenced a prolonged action of the substances in time. Even though this is not always encouraged, since possible secondary reactions may occur between the chemical residuals and the mineralogical matrix, it is important to stress the advantage related to the long-term inhibition towards a secondary biological growth on the surfaces. For these reasons, it will be important to further analyse the stability of the substances in time, by observing possible modifications in the properties of the stones during the time
What controls algal greening of sandstone heritage? An experimental approach
No full textRecent observations have shown that many sandstone buildings, including important components of the UK’s cultural heritage, are becoming covered with green algal growths. This is likely to result from recent changes in air quality and the impacts of a changing climate. The northern regions of the UK in particular have an abundance of sandstone heritage and, given the likelihood of warmer, wetter winters here, algal growth on vulnerable monuments is likely to become a primary conservation concern over the next 50 years. Observations of sandstone monuments in the northern regions of the UK, in particular in Belfast (Northern Ireland), Sheffield and Edinburgh have highlighted that algal greening is notably patchy. This is likely due to the array of factors which affect the bioreceptivity of host substrates such as sandstone. The bioreceptivity of a substrate (its ability to become colonised by microbes such as green algae) is dependent on inherent, external and architectural factors. The role of these factors and the interrelationships between them requires further study.
This thesis aims to investigate the inherent, external and architectural factors which encourage colonisation of sandstone by green algae through an integrated programme of laboratory and field experimentation. The primary objectives of this study are: to develop improved laboratory experimental methods to control and monitor algal growth, to investigate the role of external, inherent and architectural factors and to explore the fundamental role of moisture in the development of algal greening.
In order to address these objectives, laboratory and field experiments have been linked within an integrated overall methodology. Short-term laboratory experiments have investigated the bioreceptivity of four British sandstones (Peak Moor, Dungannon, St Bees and ‘baluster stone’) to single and mixed green algal treatment with Stichococcus bacillaris, Chlorella vulgaris and Desmococcus olivaceus, under controlled conditions. Two field experiments have also been conducted. The first exposed unweathered blocks of Dungannon sandstone in the wet environment of Derrygonnelly, Northern Ireland for 30 months. The second exposed reclaimed sandstone balusters in a shaded and exposed site in central Oxford for 12 months. The laboratory and field experiments presented utlilise a range of simple and accessible methods to monitor biofilm development (for example novel methods to map biomass) and changes in substrate condition (such as monitoring surface moisture movements with weight change and hand-held moisture meters, and using light microscopy to help visualise the impact of green algal biofilms).
The results presented in this thesis confirm that moisture plays a fundamental role in the development of green algal biofilms. In laboratory experiments, colonisation often occurred within a consistent moisture zone and preferential greening in field experiments was observed in areas of frequent moisture movement. External factors have been shown to have a strong influence, in laboratory experiments where marine salts were applied, these were found to delay colonisation by around seven days. Furthermore, salts resulted in inhomogeneous patterns of colonisation, similar to those observed in scoping studies conducted in Sheffield. Laboratory experiments have also demonstrated that inherent substrate factors such as high porosity and presence of certain minerals (such as clay laminations in Dungannon) can increase the primary bioreceptivity of sandstone surfaces.
Field experiments have demonstrated that architectural factors such as aspect and geometry can increase the bioreceptivity of exposed samples. In particular, preferential greening was observed on the dynamically wetted south west facing blocks in Derrygonnelly and on exposed compared with shaded balusters in Oxford. Greening was also concentrated in areas of rainwater flows and stores.
Investigation of the role of external, inherent and architectural factors in the development of algal greening as provided by this project, supplies useful information for those managing our sandstone cultural heritage. This will enable more informed decisions to be made over appropriate management and conservation strategies for the future
Conservation of history in a changing environment: a geomorphological approach
No full textOne brief glance at the UNESCO World Heritage List (August 2010) shows that currently 18 cultural sites are ‘under severe threat’. Of these, 14 are situated in arid environments. The harsh nature of these climates in combination with the often inaccessible and instable nature of their geographical location means that cultural heritage is often difficult to monitor, manage and conserve. Of the number of threats described in the ‘Case studies on Climate Change and World Heritage’ report (UNESCO, 2007), many apply specifically to arid regions such as increased erosion and weathering through desertification and salt weathering, ground water fluctuations, changes in wetting and drying cycles and extreme temperature fluctuations.
Whilst our knowledge of the causes of decay and how to control it is continually progressing, monuments are deteriorating at an alarming rate. Many stone monuments which are a testimony to and record of our history and cultural development are now at risk of fading away into the past rather than standing tall for future generations to see. Even when deterioration does not appear to be catastrophic, weathering processes are slowly chipping away at statues, fountains, doorways and foundations. This is a problem for stone-built heritage in any environment; Durham Cathedral (UK) for example recently had to be completely surveyed and substantial parts of its structure had to be replaced due to honeycombing and flaking of the stone work (Attewell and Taylor, 1990). Similarly, pollution has created problems for the future of the Cathedral of Cadiz, Spain (Torfs and Van Grieken, 1997) while sandstone weathering is damaging monuments such as Giza, Egypt (Fitzner et al, 2003). In addition, numerous reports are available discussing rapid deterioration of well-known heritage such as Petra, Jordan (Heinrichs, 2008) and Angkor Wat, Cambodia (Uchida et al, 2000). What makes weathering in arid environments different from weathering in temperate climates is the astonishing process rate. Research has shown, for example, that test blocks of stone left in the Namib desert virtually dissolved over the span of a few years (Goudie et al, 1997; Viles and Goudie, 2007). Furthermore, there are many examples of structures such as newly built housing as well as pipelines decaying badly in a matter of years (Goudie and Viles, 1997).
Arid environments are home to a vast range of different heritage sites; these vary from the stunning remains of Babylon (Iraq), where wholly intact temples, murals and houses can still be seen, to the fantastic rock art sites of the Tradat Acacus (Libya) to the extensive ruins of the trade city Paquimé Casas Grandes (USA). The entire area just north of the Tropic of Cancer is home to a vast number of UNESCO Cultural Heritage Sites, showing not only the density but also the importance of the historical and archaeological sites found in this region.
The questions that beg to be answered are ‘How bad is stone weathering in arid environments, what can we about it and what implications does it have for the future enjoyment of stone heritage?’ Placing heritage in the larger picture of war, food and water shortages and lack of education opportunities, how important is it to focus our efforts on understanding the decay of heritage? Keats’ statement could actually go a long way towards explaining the importance of preserving cultural heritage. Many of these structures are ‘things of beauty’, positive additions to our cities and landscapes and reminders of cultural achievements. The ones that are not obviously beautiful but bear historical significance such as the barracks at Auschwitz also provide an important reminder of our past. Not only can joy be found in the aesthetically pleasing structures, structures such as Auschwitz also often remind us of the ugly parts of history as well, events that should never be repeated. They may not be able to solve world-wide problems, but they can act as a reminder to prevent future events that should never take place
Royal Geographical Society (with IBG) Medals and Awards celebration 2020 and 2021
No full textThe Royal Geographical Society (with IBG) annual Medals and Awards recognise achievements in researching, communicating and teaching a wide range of geographical knowledge. The speeches and citations are a record of both the 2020 and 2021 celebrations, which were delayed and combined because of COVID-19, with contributions from Heather Viles, Andy Eavis, Rita Gardner, Jonathan Rigg, Chris Philo, Peter Kraftl, Patricia Noxolo, Emma Mawdsley and Nina Laurie. The event concluded with comments from the Society’s Patron, Her Royal Highness The Princess Royal. The speeches included comments on inspirational students and teachers; the importance of collaboration, of equity and inclusivity; understanding places, making connections and crossing boundaries; earth-writing and earth-righting
Deterioration and conservation of rock-hewn sandstone cave-temples in Longdong area, China
No full textCave-temples are multivalent types of immovable cultural heritage which link spiritual values as places for Buddhism rituals, aesthetic values because of the Buddha sculptures, inscriptions and murals they contain, historic values as significant objective evidence of the history of the eastward spread of Buddhism, as well as economic values as tourist attractions. It is, therefore, highly necessary to preserve them in a sustainable manner and pass them on to the next generation.
The Longdong area refers to the area to the east of the Long mountains, i.e. the southern section of the Liupanshan mountain chain, in Gansu Province, China. This region was also the eastern section of the Silk Road connecting the Central Plain in China to western countries. A great number of cave-temples are hewn from outcrops of the widespread sedimentary sandstone units in the region and face severe deterioration problems endangering their values and integrity. Thus, study regarding deterioration process is required in order to understand the impacts of these deterioration risks.
Accordingly, the research presented in this thesis focuses on studying and evaluating the rock deterioration and its impacts aiming to clarify the major weathering mechanisms of these cave-temples. The North Grotto Temple (NGT), situated near Qingyang, is the oldest site representing the highest artistic value of grotto art in the Longdong area, hence, was selected as the study site. The overall research comprised three phases. The first phase involved field investigation and survey of weathering features; the second phase focused on in situ detection, modelling prediction and laboratory characterization of deteriorating salts, and the third phase comprised laboratory simulation of salt weathering at North Grotto Temple and how it affects the rock properties. A range of portable non-destructive devices (including Karsten tube and surface hardness tester (Proceq Equotip® 3 and 550), ultrasonic instrument (Proceq PunditLab) were used in the research, along with a non-invasive method of sampling salts (fiber paper pulp poultices), a range of laboratory analysis and experimental methods (including ion chromatography and environment cabinet) and modelling software (thermodynamic model - ECOS-RUNSALT).
According to the research, several deterioration patterns, such as granular disintegration, efflorescence, alveolar, were identified on the NGT sandstone façade, which illustrate that salt weathering is probably the leading weathering agent at the site. A mixture of salts was predicted to form in the site, i.e. aphthitalite, bloedite, picromerite, darapskite, mirabilite, hexahydrite, starkeyite, nitromagnesite, halite, niter, and sylvite. Large diurnal variation of humidity in the site enhances the likelihood of salt weathering. Laboratory simulation showed experimentally that the salt mixtures can cause material loss, appearance changes and modify the petrophysical properties of sandstones, which badly affects the integrity of rock.
In sum, this study illustrates that the sandstone cave-temples in the Longdong area are under cumulative damage from salt weathering. Environmental control is a necessary measure in order to manage the risks threatening the on-going preservation of the sandstone cave-temples
A holistic approach to evaluating the performance of consolidants on sandstone
No full textSandstone, one of the most ubiquitous building materials around the globe and across time presents a complex range of characteristics and responses to environmental and physical erosion over time. The range of sandstone sub-types that have been used for structure and decorative carving through history was highly variable but is diminishing as a resource as more and more quarry sites are worked out or closed. This process has led to the use of ‘replacement’ stones in conservation work which are sourced from a small number of known sites and are similar to historic types in appearance if not age or internal characteristics. This project examines one of these replacement stones, Locharbriggs sandstone from Dumfries in Scotland, and couples it with two of the most commonly used silane consolidants in order to improve the understanding of the performance of both in lab and field conditions.
The project begins by taking observations on site at Kenilworth Castle (Warwickshire, UK) shaping the research through the identification of areas of concern for the conservation of historic sites, such as erosion driven by visitor footfall and the effects of prior treatment applications. These are used to formulate an experimental programme which combines lab and field experiments, and begins with the development of a method for artificially weathering the stone substrate using the controlled application of heat, in preparation for consolidation.
The field-based experimental work, hosted at the Wytham Woods research site near Oxford UK, examines the uses and limitations of two forms of field trial; the exposure of laboratory-prepared stone samples on a purpose-built exposure rack, and the incorporation of stone samples of variable size and treatment within a purpose-built test structure. Both experiments trial a range of assessment metrics for the detection and monitoring of consolidants applied to the samples, within the context of exposure to local weather conditions. In addition to these experiments, a further trial was hosted by SATRA Technologies (Kettering, UK) which utilises a mechanical prosthetic leg to simulate physical abrasion analogous to that observed on site, modelling the type of wear driven by footfall across exposed stone surfaces.
These experiments trial the use of a range of systems for the assessment of stone condition and consolidant performance, combining those which are understood in other heritage contexts with the novel combination of handheld optical and laser scanners for the detection of change on samples. These are formalised into a ‘toolkit’ of methods and instruments that can be applied to sandstone- consolidant experiments, including novel methods of visualising and analysing data.
The thesis concludes that the range of assessment techniques trialled here have a range of useful applications in the detection of consolidants in heritage sandstone and for the detection of change on site and in laboratory conditions, and that there is significant scope to employ them in a range of conservation applications
Developing relations between heritage conservation and urban revitalization: lessons from China
No full textThe overall aim of this thesis is to further understanding of the developing relations between heritage conservation and urban revitalization, by following the on-going World Heritage List nomination process for the Grand Canal in China. A review of the history and current situation of heritage conservation and urban revitalization establishes several key gaps in knowledge, for example, the field of systematic heritage conservation is still left blank. Taking advantage of the opportunity to work with this on-going nomination, the project examines the nature and challenges of heritage conservation research and practice for a heritage property of large scale and complexity, in the form of four linked studies. A critique of the national level nomination process to date illustrates the complexity of the task, and concludes that systematic heritage conservation has not been established as a concentrated and nation-wide heritage conservation activity in China. Focusing on the municipal level nomination process to date through a case study of the city of Zhenjiang (and Yangzhou as a comparator) establishes key reasons why one city has been more successful than the other in its participation in the World Heritage List nomination. A second case study, of the Xi Jin Ferry area in Zhenjiang (Jiangsu Province), provides a fuller account of the ways in which heritage conservation can contribute to, and work with, urban revitalization. Drawing on the case of Xi Jin Ferry, a theoretically-informed, but practically-viable approach to linking heritage conservation and urban revitalization is developed which learns from the past and looks to the future. Building on the empirical research projects, a critique of existing approaches to heritage conservation of large, complex sites leads to a proposal for a 'Heritage System' framework which would facilitate future evaluations and improve the prospects for on-going management of the Grand Canal
The effects of open shelters on the preservation of limestone remains at archaeological sites
No full textShelters, as preventive conservation methods, have traditionally been considered a better option than leaving the site exposed. However, there has been limited research on their effect on the preservation of heritage materials and, as a result, there is no clear scientific evidence to support sheltering. This study aims to provide the first rigorous scientific assessment of the effect of lightweight, open shelters on limestone deterioration at archaeological sites. A method based on the use of low-cost environmental monitoring equipment and limestone blocks and tablets (as indicators of decay) has been developed to determine the degree of protection provided by the shelters at the Bishop’ Palace (Witney, England) and Hagar Qim (Malta). Preliminary visual assessments of the field sites were followed by 12-18 month exposure trials. Temperature extremes and fluctuations, frost events, relative humidity extremes and fluctuations, NaCl crystallisation events, solar radiation, wetting events, salt content, atmospheric pollutants and dust deposition were monitored. In addition, stone decay was studied by analysing changes in weight, elasticity, surface hardness, ultrasonic pulse velocity, surface colour, moisture content and general appearance (microscopic and macroscopic pictures) in stone samples. An exhaustive assessment of the shelter at the Bishop’s Palace was carried out using Chalk, Cotswold and Portland limestone blocks as well as Portland limestone tablets (specifically for studying dissolution, soiling and biological growth). Additionally, a comparative assessment of the effects of the two shelters in contrasting climatic environments, the Bishop’s Palace (temperate maritime) and Hagar Qim (Mediterranean), was undertaken by monitoring Globigerina and Coralline limestone blocks simultaneously at both sites. The research has shown that lightweight, open shelters do not exclude decay completely but minimise it. However, there are some areas at higher risk of decay, i.e. top parts of the walls and the periphery. In addition, problems with the shelter design can enhance some decay mechanisms, such as biocolonisation on the periphery at the Bishop’s Palace and dust deposition under the shelter at Hagar Qim. Therefore, the effectiveness of shelters should not be assumed
A holistic approach to diagnose deterioration of rock-cut structures in Lalibela, Ethiopia
No full textRock-cut architecture is made through a subtractive process of removing material from rock outcrops or cliff faces to create spaces. Rock-cut sites are at the intersection of the natural and built environments, producing a unique semi-natural setting in which both naturally existing geological features and human activities contribute to their deterioration. This thesis develops a holistic approach to diagnosing deterioration of rock-cut structures by focusing on the rock-cut church complex at Lalibela, Ethiopia. The diversity of rock-cut church types in the UNESCO world heritage site of Lalibela makes it a suitable case study to investigate the factors that influence the deterioration of rock-cut structures.
In semi-natural settings, key drivers of weathering can be broadly classified into climate, lithology, architectural form and history of conservation. These drivers were investigated in Lalibela using field studies, laboratory-based experiments and archival resources to develop a comprehensive understanding of weathering of rock-cut sites.
Rock-cut sites share lithological characteristics; many of them are built in low-strength rock outcrops. This inherent characteristic is correlated with the presence of secondary minerals such as swelling clays. The churches at Lalibela are carved from basaltic scoria that contains > 30 \% swelling clays. The climate at Lalibela is characterised by intense seasonal rainfall (main rains season) and high rock-surface temperature fluctuations (dry season). High, but fluctuating relative humidity (RH) and intense rainfall during the main rains season are favourable conditions for surface and deep-seated wetness and for frequent wetting-drying cycles to occur. To determine the impact of wetting-drying cycles on clay swelling/shrinkage and salt crystallisation/dissolution cycles, dilatation was measured in salt-free and salt- contaminated basaltic scoria samples in simulated wetting-drying cycles. Results showed that the introduction of salt (NaCl) to clay-rich basaltic scoria can substantially accelerate decay and that the range of RH fluctuations at Lalibela can cause significant dilatation.
The architectural form influences the degree of exposure of rock-cut structures to climatic variables such as rainfall and insolation. Moisture dynamics assessments done in the main rains and dry seasons demonstrated that the saturation state of the walls is influenced by exposure of the roofs to rainfall. Salt distribution assessments showed that the thickness of the walls (which lack foundations to retard the flow of moisture) influences salt loading. Conservation at Lalibela has mainly focused on protecting the exposed roofs from water ingress and has often been destructive or altered the cultural landscape. Revisiting traditional conservation techniques that mimic soft capping may present a new opportunity to preserve the sites in a manner that is in keeping with the intangible heritage values of the site.
A holistic methodology to understand the processes that lead to the deterioration of rock-cut architecture should be based on a semi-natural site framework, as has been attempted in this thesis. Two scales of approach are recommended to assess the state of and threats to the preservation of rock-cut structures: architectural form and landform. The architectural form will influence micro-climate, moisture dynamics and salt distribution, and overall, the post-exposure history of transformation and conservation of rock-cut sites. At the landform scale, inherited properties (pre-exposure history) such as topography and geological discontinuities can influence weathering.
By identifying and assessing the key drivers of weathering of rock-cut structures, this thesis lays the foundation for a scientific approach to understanding the deterioration of rock-cut architecture, which can be applied elsewhere beyond the seasonal tropical environments of northern Ethiopia
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