U-Pb monazite data for the Ardnish and Sgurr Breac pegmatites in the SW Moine block give Knoydartian ages of 827 2 and 784 1 Ma respectively. Structural and metamorphic studies of the pegmatites and the local Moinian metasediments suggest that pegmatite generation was a consequence of localized high-temperature shearing and metamorphism within the pelitic horizons. Petrographic evidence from the sheared pelites is interpreted as indicating that the local garnet-grade metamorphism was contemporaneous with the shearing and pegmatite generation, and was, therefore, Knoydartian in age. Chemical zoning profiles in garnets are consistent with their growth during prograde regional metamorphic increases in P and T. The c. 45 Ma difference between the pegmatite ages implies that the Knoydartian tectonothermal event was diachronous, being either a prolonged or episodic event. The metamorphic and geochronological data are consistent with the presence of Neoproterozoic orogenic events in the SW Moine.

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Methods employed for surveying buildings for condition have traditionally been reliant upon visual assessment and manual recording. Survey of traditional masonry also ostensibly conforms to this approach but, due to the sheer volume of masonry units composing walls, it is often prohibitively time consuming, exceptionally complex and ultimately costly. Notable features of such survey work for ashlar stone types require each stone to be labelled and overlaid with information relative to condition. Further hindering these already costly operations, it has been shown that the accuracy of reporting, including labelling the manifestation of defects and defect diagnosis, is subjective, depending upon the expertise and experience of those evaluating the fabric. Moving beyond these preliminary survey and reporting stages, this situation gives rise to variable repair and maintenance strategies that can have significant cost implications and can debase fundamental conservation activities. The development of digital technologies, such as terrestrial laser scanning, and advancements in novel computer vision statistical techniques can help produce accurate representation of buildings that can be subsequently rapidly processed, achieving many tangible survey functions with greater inherent objectivity. In this paper, an innovative strategy for automatic detection and classification of defects in digitised ashlar masonry walling is presented. The classification method is based on the use of supervised machine learning algorithms, assisted by surveyors' strategies and expertise to identify defective individual masonry units, through to broader global patterns for groups of stones. The proposed approach has been tested on the main façade of the Chapel Royal in Stirling Castle (Scotland), demonstrating its potential for ashlar masonry forms of wall construction. It is important to recognise that the findings are not limited to this culturally significant building and will be of high value to almost innumerable ashlar-built structures worldwide. The research ultimately attempts to reduce the degree of subjectivity in classifying defects, on a scale and rapidity hitherto beyond traditional project cost constraints. Importantly, it is recognised that through automation more effective utilisation of resources that would have been traditionally spent on survey can be redeployed to support fabric intervention or routine maintenance operations.

Two pegmatites and mylonitic rocks from the Grampian Shear Zone yield U–Pb monazite ages of 806 ± 3 Ma, 808 –9 +11 Ma, and 804 –12 +13 , respectively. These confirm that shearing and pegmatite crystallization was essentially synchronous. Lower intercepts of c. 440 Ma indicate disturbance during Ordovician reworking. These new data question the concept of a single latest Proterozoic–early Palaeozoic orogeny in the Grampian terrane and the significance of the Great Glen Fault.

The age and formation of zircons in Neoproterozoie migmatites from the northern Grampian Highlands are assessed using field observations, imaging and U-Pb isotope dilution techniques. Acicular zircons within monzogranitie leucosomes provide evidence for neocrystalline growth during localized anatexis. U-Pb zircon data show that formation of the regional gneissose fabric, melt generation and new zircon growth occurred at 840 ±11 Ma contemporaneous with peak metamorphism. These data and previously dated shear fabrics at c. 800 Ma, confirm that a Neoproterozoic tectonometamorphic event affected at least part of the metasedimentary sequence southeast of the Great Glen Fault. Data from detrital zircons indicate a Palaeoproterozoic/Grenville province, rather than Archaean, as the most likely source for the sedimentary protolith. In the absence of identifiable orogenic discontinuities within the Scottish Highlands, we question current correlations with Laurentian passive margin sequences, and the inferences that the rocks of the Grampian Block only experienced a simple Caledonian (Palaeozoic) orogenic history.