Hyperspectral imaging data holds great potential for the different stages of the mining life cycle in active and post-mining environments. However, the technology has yet to reach the stage of large-scale industrial implementation and acceptance. While hyperspectral satellite imagery can achieve high spectral resolution, signal-to-noise ratio (SNR) and global availability with break-through satellite systems like EnMAP, EMIT and PRISMA, limited spatial resolution poses chal-lenges for sectors like mining, which require decimetre to centimetre scale resolution for applica-tions such as reconciliation, ore/waste estimates, geotechnical assessments and environmental monitoring. Hyperspectral imaging from drones (referred to herein as Uncrewed Aerial Systems; UASs) offers high spatial resolution data relevant to the camp/ mine scale, with the capability for frequent, user-defined re-visit times. This has been made possible by the miniaturization of hy-perspectral imaging systems. Collection of data in the visible to near and shortwave infrared (VNIR-SWIR) wavelength regions enables the detection of different minerals and surface altera-tion patterns potentially revealing crucial information for exploration, extraction, re-mining, waste remediation, and rehabilitation. In this paper, we provide a review of relevant studies de-ploying hyperspectral imaging in or applicable to the mining sector, especially for the use of hy-perspectral VNIR-SWIR Uncrewed Aerial Systems. Where required, we draw on previous in-sights derived from satellite or ground-based systems. We also discuss UAS survey planning, and sampling considerations for validation and interpretation.

Sedimentation on river floodplains is a complex process that involves overbank flooding, crevasse splaying, and river avulsion. The resulting floodplain stratigraphy often exhibits floodplain aggradation cycles with alternating fine-grained overbank flooding deposits that underwent significant petrogenesis, and coarser-grained, avulsion-belt deposits largely devoid of pedogenic impact. These cycles are linked to lateral migration and avulsion of channels driven by internal dynamics, external factors, or a combination of both. To better understand the spatial and vertical variability of such floodplain aggradation cycles, we map these in three dimensions using a photogrammetric model of the lower Eocene Willwood Formation in the northern Bighorn Basin, Wyoming, USA. This allows identifying 44 floodplain aggradation cycles in ∼300 m of strata with an average thickness of 6.8 m and a standard deviation of 2.0 m. All the cycles are traceable over the entire model, pointing to their spatial consistency over the 10 km2 study area. At the same time, rapid lateral thickness changes of the floodplain aggradation cycles occur with changes up to 4 m over a lateral distance of 400 m. Variogram analyses of both field and numerical-model results reveal stronger consistency of floodplain aggradation cycle thicknesses along the paleoflow direction compared to perpendicular to paleoflow. Strong compensational stacking occurs at the vertical scale of 2−3 floodplain aggradation cycles (14−20 m), while full compensational stacking occurs at larger scales of more than six floodplain aggradation cycles (>41 m). The lateral and vertical thickness variability of the floodplain aggradation cycles, as well as their compensational stacking behavior, are interpreted to be dominantly driven by autogenic processes such as crevasse splaying and avulsing that preferentially fill topographic lows. External climate forcing may have interacted with these autogenic processes, producing the laterally persistent and vertically repetitive floodplain aggradation cycles. The spatial variability of floodplain aggradation cycles demonstrated in this study highlights again the need for three-dimensional data collection in alluvial floodplain settings rather than depending on one-dimensional records.

Abstract Traditionally, field geology and the use of outcrop analogues have been crucial to aid subsurface understanding, with fieldwork and excursions playing an important role in the training and continued professional development of multidisciplinary geoscientists. The COVID-19 pandemic caused a major disruption to industry training programs and university geoscience courses as travel restrictions and lockdowns created the need for digital alternatives. Although virtual field trips (VFTs) had been gaining traction prior to the pandemic, the sudden need to replace physical field activities has driven a rising interest to allow geologists and geoscientists to keep in touch with the rocks. In this contribution we present the state of the art of virtual field trips, covering the process of conceptualizing and building a VFT, as well as delivery methods available. We argue that VFTs have an important place in geoscience education, not as a replacement for physical field trips, but as a complement to assist participants’ orientation prior to a course, retention of learning outcomes post-trip, as well as an enabler of accessible and non-discriminatory experience of field geology to a wider group of people than those conventionally given the opportunity for physical excursions. Central to the successful creation of virtual field trips is the availability of 3D virtual outcrops and other geospatial data to populate a VFT. Databases of virtual outcrops, such as SAFARI and V3Geo, make it efficient to create a high-resolution framework for a field trip, which is then used to integrate conventional field or subsurface data. Finally, the VFT leader adds their narrative and learning process around the 3D virtual environment and delivers the content to participants. A VFT can be organized by topic (e.g. depositional environment or structural setting) rather than restricted to a limited geographical area. In addition, a VFT can be created to fit any available timescale, from a tour lasting minutes to look at a particular geological feature, through to a multi-day agenda mirroring a conventional field trip. We illustrate our contribution using example VFTs designed for different audiences and geological topics.

V3Geo is a cloud-based repository for publishing virtual 3D models in geoscience. The system allows storage, search and visualisation of mesh models typically acquired using techniques such as photogrammetry and laser scanning. The platform has been developed to handle models at the range of scales typically used by geoscientists from microscopic, hand samples and fossils through to outcrop sections or terrain covering metres to tens of kilometres. The cloud storage system serves the models to a purpose-built 3D web viewer. Models are tiled to ensure efficient streaming over the Internet. The web viewer allows 3D models to be interactively explored without the need for specialist software to be installed. A measurement tool enables users to gauge simple dimensions, such as widths, thicknesses, and fault throws. V3Geo allows very large models comprising multiple sections and is designed to include additional interpretation layers. The specific focus on geoscience data is supported by defined metadata and a classification schema. Public and private storage is available, and public models are assigned Creative Commons licenses to govern content usage. This paper presents V3Geo as a sustainable resource for the geoscience community, including the motivation and main characteristics and features. Example usage scenarios are highlighted: from undergraduate geology teaching, supporting virtual geoscience education and preparing virtual field trips based on V3Geo models. Finally, best practice guidelines for preparing 3D model contributions for publication on V3Geo are included as the Appendix.

Geological models from outcrop analogues are often utilized as a guide, or soft constraint, for distributing reservoir properties in subsurface models. In carbonate outcrops, combined sequence stratigraphic, sedimentological, and petrographic studies constrain the heterogeneity of geobodies and diagenetic processes, including dolomitization, at multiple scales. High-resolution digital outcrop modeling further aids geometric mapping, geobody definition, and statistical analysis, though its usefulness for detailed mineralogical and lithological mapping is limited. Hyperspectral imaging offers enhanced spectral resolution for mapping subtle mineralogical differences. In both outcrops and subsurface, differences in carbonate composition can provide key information for distributing porosity and permeability, yet this mapping is highly challenging in field studies due to access difficulties, visible material differences, and sampling resolution. Spectral analysis of limestone-dolomite ratios conducted in laboratory studies indicates theoretical measures for quantitative identification and mapping of dolomite degrees within carbonate rocks. In this study, close-range hyperspectral imaging is applied to outcrops of the Alacon Member, Barranco del Mortero, northeastern Spain, to identify exposed limestone-dolomite geobodies and to quantify the degree of dolomitization across outcrop faces. Hyperspectral imaging is supplemented with photogrammetric outcrop modeling, field spectroscopy, and laboratory sample analysis for empirical validation and uncertainty analysis. Hyperspectral mapping shows that earlier fieldwork utilizing visual inspection of difficult to access outcrop surfaces had overestimated the amount of dolomite in the outcrop. Results indicate that hyperspectral imaging identified dolomite bodies more accurately and reliably than conventional field methods and facilitates the mapping of dolomite contribution in areas modified by dedolomitization, where dolomite content changes by more than similar to 20%.

The advent of photorealistic, 3D computer models of cliff sections (virtual outcrops) has improved the immersive nature of virtual geological field trips. As the COVID-19 pandemic led to widespread national and international travel restrictions, virtual field trips (VFTs) became practical and essential substitutes for traditional field trips and accelerated the development of VFTs based on virtual outcrop data. This contribution explores two such VFTs delivered to a masters level Integrated Petroleum Geoscience course at the University of Aberdeen. These VFTs are based on traditional field trips that are normally run to the Spanish Pyrenees and Utah (USA). The paper summarizes the delivery mechanism for VFTs based on virtual outcrops and examines student perception, gauged primarily through questionnaires and learning outcomes. The VFTs were run in LIME, a software specifically designed for the interpretation of 3D models and the delivery of VFTs. Overall, the student perception was very positive and comparable to satisfaction with the conventional trips. Staff feedback and student assessments suggest that the learning outcomes were satisfied and highlight the value of this method of teaching for students who are unable to attend the field trip and as an addition for those who can.

This paper compares the feasibility of classifying building façade materials in situ via a low-cost multispectral imaging camera with 5 bands compared to a high-cost, short-wave infrared hyperspectral unit with 240 bands. The sensors were used to classify five common façade materials: brick, mortar, stone, painted window frames, and rendering. The data were subjected to a Partial Least Squares Discriminant Analysis by selecting 95 training pixels and 65 validation pixels for each material. Across all materials, the hyperspectral imaging demonstrated a moderate advantage over multispectral imaging (with a correct classification rate of 99% versus 80%) for the selected data and stronger qualitative matching to the entire façade. While the hyperspectral data were consistently superior, the multispectral data still produced valuable results, thereby demonstrating potential as a fast, easy, and much cheaper technology compared to hyperspectral units for in situ façade materials classification.

Abstract. The Covid-19 pandemic occurred at a time of major revolution in the geosciences – the era of digital geology. Digital outcrop models (DOMs) acquired from consumer drones, processed using user-friendly photogrammetric software and shared with the wider audience through online platforms are a cornerstone of this digital geological revolution. Integration of DOMs with other geoscientific data, such as geological maps, satellite imagery, terrain models, geophysical data and field observations strengthens their application in both research and education. Teaching geology with digital tools advances students’ learning experience by providing access to spectacular outcrops, enhancing visualization of 3D geological structures and improving data integration. Similarly, active use of DOMs to integrate new field observations will facilitate more effective fieldwork and quantitative research. From a student’s perspective, geo-referenced and scaled DOMs allow an improved appreciation of scale and of 3D architecture, a major threshold concept in geoscientific education.In view of the Covid-19 pandemic, DOMs allow to bring geoscientists to the outcrops digitally. At the University Centre in Svalbard (UNIS), located at 78° N in Longyearbyen in Arctic Norway, DOMs are actively used even in non-pandemic years, as the summer field season is short and not overlapping with the Bachelor “Arctic Geology” course package held from January to June each year. In 2017, we at UNIS developed a new course (‘AG222: Integrated Geological Methods: from outcrop to geomodel’) to encourage the use of emerging techniques like DOMs and data integration to solve authentic geoscientific challenges. In parallel, we have established the open access Svalbox geoscientific portal, which forms the backbone of the AG222 course activities and provides easy access to a growing number of DOMs, 360° imagery, subsurface data and published geoscientific data from Svalbard. Considering the rapid onset of the Covid-19 pandemic, the Svalbox portal and the pre-Covid work on digital techniques in AG222 allowed us to rapidly adapt and fulfill at least some of the students’ learning objectives during the pandemic. In this contribution, we provide an overview of the course development and share experiences from running the AG222 course and the Svalbox platform, both before and during the Covid-19 pandemic.

Abstract. Virtual geological fieldtrips have become increasingly popular over the last decade, with the advent of remote piloted vehicles (RPVs; drones) leading to progressively sophisticated photorealistic virtual outcrops (VOs). As the COVID-19 pandemic led to widespread international travel restrictions, virtual fieldtrips (VFTs) became practical, and necessary substitutes for traditional fieldtrips. This contribution explores two VFTs delivered to a master’s level Petroleum Geoscience course at the University of Aberdeen, normally run as traditional fieldtrips to the Spanish Pyrenees and Utah. The paper describes the delivery of these VFTs and examines student perception, gauged primarily through questionnaires. The VFTs were run in LIME, a software specifically designed for the interpretation of 3D models and the delivery of VFTs. Overall, the student questionnaires reflect the satisfaction of group with the teaching method and feedback was more positive for the virtual fieldtrips than the equivalent real-world trips in earlier years. Our findings also highlight several notable advantages associated with VFTs, including the ability to examine geology data at a range of scales, financial and access inclusivity, and reduced environmental impact. Several disadvantages with VFTs were also highlighted, including a reduction in social cohesion, and missing out on the experience of travelling and being outdoors. Our findings highlight implications for future application of VFTs and the opportunity to utilise both traditional fieldtrips and VFTs within a blended learning approach.

13 Interaction of allogenic and autogenic forcing in building alluvial stratigraphy remains a complex 14 subject that is critical for paleoenvironmental and paleoclimate reconstruction and subsurface rock 15 property prediction. Astronomical forcing of alluvial stratigraphy is poorly documented so far as this 16 driver strongly interacts with autogenic and other allogenic processes making it difficult to trace 17 astronomical climate changes in these laterally highly variable sediments. In the lower Eocene Willwood 18 Formation, Bighorn Basin, Wyoming, USA, a lot of evidence has been gathered to relate dominant 19 floodplain aggradation cycles to precession-scale climate change. One floodplain aggradation cycle 20 consists of two phases: (1) a longer overbank phase with relative channel stability and strong paleosol 21

Over the past five years the use of 3D models in the Earth Sciences has become ubiquitous. These models, termed Virtual outcrops, are most commonly generated using Structure from Motion (SfM) photogrammetry, an image-based modelling method that has achieved widespread uptake and utilization. Data for these models is commonly acquired using remotely piloted aerial vehicles (RPVs), commonly called drones. The purpose of this document is to present a basic acquisition methodology, which is based on the workflows used by the authors for the acquisition of over 500 virtual outcrops over the last decade. This article is part of a series from the editors of V3Geo, which is an online forum for sharing high quality virtual 3D geoscience models. Virtual outcrops submitted to V3Geo are subject to a technical quality control to ensure that data can be reliably utilized by the wider professional and scientific community. This document provides guidelines for the robust acquisition of data which are required to build high quality models suitable for sharing in V3Geo. The document focuses on outcrop selection, mission planning, RPV setup, data acquisition and management. Related documents in this series cover data processing and model building.

The study describes the depositional development and sediment partitioning in a prograding paralic Triassic succession. The deposits are associated with the advance of large prism-scale clinoforms across a shallower platform area. Approaching the platform, the limited accommodation and associated relative higher rates of deposition generated straighter clinoforms with lower foreset angles. The vertical restriction across the platform is interpreted to have amplified the tidal signature. Sediment was redistributed from the coast into increasingly sandy delta-front deposits, compared to offshore equivalents. The deposits comprise extensive compound dune fields of amalgamated and increasingly clean sandbodies up-section. Rapid deposition of significant amounts of sand led to differential subsidence and growth-faulting in the delta front, with downthrown fault blocks further amplifying the tidal energy through funnelling. A mixed-energy environment created along-strike variability along the delta front with sedimentation governing process-regime. Areas of lower sedimentation were reworked by wave and storm-action, whereas high sedimentation rates preserved fluvially dominated mouth bars. A major transgression, however, favoured tidally dominated deposits also in these areas, attributed to increasing rugosity of the coastline. Formation of an extensive subaqueous platform between the coast and delta front dampened incoming wave energy, and tidally dominated deposits dominate the near-shore successions. Meanwhile formation of wave-built sand-bars atop the platform attest to continued wave influence. The strong tidal regime led to the development of a heterolithic near-shore tidally dominated channel system, and sandier fluvial channels up-river. The highly meandering tidal channels incising the subaqueous platform form kilometre wide successions of inclined heterolithic stratification. The fluvially dominated channels which govern deposition on the delta plain are narrower and slightly less deep, straighter, generally symmetric and filled with cleaner sands. This study provides important insight into tidal amplification and sand redistribution during shallowing on a wide shelf, along with along-strike process-regime variability resulting from variations in sediment influx.

V3Geo is a cloud-based repository for virtual 3D models in geoscience, allowing storage, searching tools and visualisation of 3D models typically acquired through photogrammetry (structure-from-motion), laser scanning or other laboratory-based 3D modelling methods. The platform has been developed to store and access 3D models at the range of scales and applications required by geoscientists – from microscopic, hand samples and fossils through to outcrop sections covering metres to tens of kilometres. A 3D web viewer efficiently streams the model data over the Internet connection, allowing 3D models to be explored interactively. A measurement tool makes it possible for user to measure simple dimensions, such as widths, thicknesses, fault throws and more. V3Geo differs from other services in that it allows very large models (consisting of multiple sections), is designed to include additional interpretations in future versions, and focuses specifically on geoscience through metadata and a classification schema.The initial version of V3Geo was released in 2020 in reaction to the COVID-19 pandemic, with the aim of providing virtual tools in a time of cancelled field excursions, field-based courses and fieldwork. The repository has been accepting community contributions, based on a guideline for preparing and submitting high quality 3D datasets. Contributions are subject to a technical review to ensure underlying quality and reliability for scientific and professional usage. Model description pages give an overview of the datasets, with references, and datasets themselves are assigned Creative Commons licences. The 3D viewer can be embedded in webpages, making it easy to include V3Geo models in virtual teaching resources. V3Geo allows increased accessibility to field localities when travel or mobility is restricted, as well as providing the foundation for virtual field trips. The database currently includes around 200 virtual 3D models from around the world, and will continue to develop and grow, aiming to become a valuable resource for the geoscience community. Future updates will include tools to facilitate upload and technical review, interpretations and Digital Object Identifiers.

In September 2020, the Corona crisis offered us an opportunity to develop and test a blended real and virtual interdisciplinary field mapping class, as well as revealing the need for, and stimulating development of new web-based tools for structural interpretation.Universität Mainz’ usual Master’s advanced field mapping, and Universität Tübingen’s usual Bachelor’s mapping classes were replaced with combinations of (i) virtual field mapping of Jurassic-Cretaceous sedimentary units at Molinos, Teruel Province, Spain, and (ii) field mapping of metamorphic rocks in the Mittelrhein Gorge and the Arh Valley, and outcrops of sedimentary rocks near Tübingen, Germany, which the students were mostly able to access on day trips using public transport or by bicycle.For the Molinos part of the exercise both groups were offered hand specimens containing distinctive fossils, linked to locations (and pseudo-locations) by google .kmz files, a variety of structural measurements also linked via .kmz files, and detailed satellite imagery within which mappable geological units display distinct characteristics. Introductions to the stratigraphy were made in three virtual outcrop sections examined in Google Street View from within Google Earth, and via web-based photogrammetric 3D outcrop models made available on the V3Geo virtual 3D geoscience platform. The students then extrapolated this stratigraphy based on the satellite imagery and .kmz file information.Our perception, validated by student feedback, is that the real parts of both field excursions were very important since they allowed us to teach and refine mapping and compass methodology and best demonstrate how to analyze 3D geometries of geological structures. Universität Mainz students particularly benefited from being able to visit locations where we had already made 3D outcrop models and offered a digital excursion, in the Ahr Valley (Rhenish Massif). They were able to compare real structural measurements with those derived from the precisely georeferenced 3D models, which enhanced their ability to subsequently obtain such information solely from the models. Although final student maps were of comparable quality to those produced in the field, structural interpretations were hampered by a lack of field measurements. In many cases, the Google Earth DEM is of too low resolution and ways should be found to include higher-resolution DEMs in web-based data sets.Overall, we think there were advantages compared to traditional field mapping, such as (i) enhanced evidence that methods like ‘structure contouring’ were used in all mapping, (ii) we were stimulated to teach the students to use digital methods to acquire field data, such as StraboSpot and Stereonet11 Apps. We observed these tools, and others we were unaware of, being used in combination with traditional paper and compass during the real mapping exercise. We hope to continue to employ this blended teaching approach even when the Corona crisis passes. This will be facilitated by our development of further 3D outcrop models, .kmz files with key information about outcrops in the Mittelrhein, and especially, web-based (rather than PC-based) tools to extract structural data such as plane and line orientations from 3D outcrop models and enable collaborative work on one data set.

Retrograde metamorphism corresponds to the metamorphic processes that occur during orogenic uplift (diminishing temperatures) and cooling (lowering temperatures). These pressure and temperature conditions induce fracturing and fluids circulation which may prompt the crystallization of fibrous actinolite and tremolite within magnesium-iron rich rocks. Such fibrous amphiboles may result from the destabilization of earlier minerals (magmatic or metamorphic pyroxenes and/or amphiboles). In all cases, fibrous occurrences concern discrete locations and limited extents in space. These Naturally Occurring Asbestos minerals only form along fracture planes (in slip-vein mode) or within open veins (cross-vein mode). That is in the space where fluids circulated. Actinolite and tremolite minerals also crystalize inside mafic rock matrix, though not under their asbestiform habitus. Altering fluids diffuse from vein walls into the rock and actinolite and tremolite substitute themselves to destabilized pyroxenes and amphiboles of the matrix. This deliberately simplified geological logic may be used to predict the location of Naturally Occurring Asbestos (NOA) on different rock outcrops.We contend that 3D digital outcrop models commonly acquired by photogrammetry (ground- or UAV-based) alone or together with lidar, are efficient supports to map NOA presence susceptibility using this conceptual model. The rock assemblage architecture is best interpreted either in 3D, on a photorealistic textured meshed model itself, or on 2D orthophotos projected on a vertical plane. Geometric processing of dense (centimeter-resolution) 3D point clouds enables identifying host structures (fractures, faults and layer contacts) in the outcrop relief. Already, with these information supported by field observations, a first model may be produced for most likely NOA sites on the outcrop. If hyperspectral imaging in the shortwave infra-red (1300-2500 nm) spectral range, constrained by point-based field spectrometer acquisition, is added to the pool of available data sets, diffuse alteration rings of the mafic rock matrix may be imaged and included to the presence susceptibility model. Amphibole mineralogy provides diagnostic spectral properties due to hydroxyl absorption and can be therefore identified and mapped by hyperspectral imaging in the outcrop.This theoretical approach to mapping NOA presence susceptibility is demonstrated on examples from Norway and France. Ground-based photogrammetric survey replicates the geometry and colour of the outcrop with a dense point cloud spacing of 1pt/15-20 mm and a photorealistic textured meshed model. Lithological architecture and structural interpretation were performed manually using LIME software (virtualoutcrop.com). Geometric fracture mapping was undertaken using CloudCompare (cloudcompare.org) with the Compass and Facets plugins. Both lithological and structural information were brought together on a 2D NOA presence susceptibility map using Geographic Information System. This output, validated in the field, guides rock sample collection for laboratory analysis and objectivates their spatial representatitivity for NOA presence susceptibility reports.

The high Arctic is a remote place, where geoscientific research and teaching require expensive and logistically demanding expeditions to make use of the short field seasons. The absence of vegetation facilitates the use of modern photogrammetric techniques for the cost-effective generation of high-resolution digital outcrop models (DOMs). These georeferenced models can be used in pre-fieldwork activities to help prepare for traditional geological fieldwork, during fieldwork to record observations, and post-fieldwork to conduct quantitative geological analyses. Analyses of DOMs range in scale from mm-cm (e.g., size and spacing of dinosaur footprints), to hundreds of meters (e.g., seismic modeling of outcrops and outcrop-well-seismic correlations) and can advance research objectives. This integration is strengthened if key geoscientific data, like geological and topographical maps, subsurface profiles, borehole data, remote sensing data, geophysical data and DOMs can be integrated through a common database, such as the Svalbox database that we present in this commentary. Svalbox geographically targets the Svalbard archipelago, where fieldwork is challenging due to the harsh polar environment, risk of polar bear encounters and demanding transport to the field area. The University Centre in Svalbard nonetheless relies on utilizing the natural Svalbard environment for its field-based education, and now makes use of Svalbox to make geological fieldwork more efficient and post-fieldwork analyses more quantitative. Experience and usage of such tools in geoscientific education, particularly in the polar regions, is not well documented. Therefore, we share experiences on both developing and optimizing Svalbox, and on student and lecturer usage. Svalbox includes a web-based interface through which DOMs are shared and displayed together with relevant public-domain geoscientific data sets. Svalbox also serves as a platform to share student and teacher experiences on the entire DOM workflow, from acquisition to data distribution. For the Svalbox users questioned by the project group, DOMs were found to provide many benefits, including quantitative analyses, extended field season, appreciation of scale and data sharing that significantly outweigh present-day challenges, such as the need for expensive hardware and lack of easily accessible interpretation software, the latter being surmountable within the near-term.

Despite the importance of channel avulsion in constructing fluvial stratigraphy, it is unclear how contrasting avulsion processes are reflected in stratigraphic-stacking patterns of channelized fluvial sand bodies, as a proxy for how river depocenters shifted in time and space. Using an integrated, geospatially referenced, three-dimensional data set that includes outcrop, core, and lidar data, we identify, for the first time in an outcrop study, a predictive relationship between channelized sand body architecture, paleochannel mobility, and stratigraphic-stacking pattern. Single-story sand bodies tend to occur in vertically stacked clusters that are capped by a multilateral sand body, indicating an upward change from a fixed-channel system to a mobile-channel system in each cluster. Vertical sand body stacking in the clusters implies reoccupation of abandoned channels after "local" avulsion. Reoccupational avulsion may reflect channel confinement, location downstream of a nodal avulsion point that maintained its position during development of the sand body cluster, and/or aggradation and progradation of a backwater-mediated channel downstream of a nodal avulsion point. Sand body clusters and additional multilateral sand bodies are laterally offset or isolated from each other, implying compensational stacking due to "regional" switching of a nodal avulsion point to a new, topographically lower site on the floodplain. The predictive links between avulsion mechanisms, channel mobility, and resultant sand body distributions and stacking patterns shown in our findings have important implications for exploring and interpreting spatiotemporal patterns of stratigraphic organization in alluvial basins.

ALONGSIDE THE GROWTH and expansion of spatial data in the geosciences and society in general, virtualand augmented-reality technology has been providing exciting avenues to explore spatial data in an immersive, intuitive and collaborative way. New virtual and augmented headsets and the growth of 3D spatial data have allowed the creation of novel immersive experiences within the scientific community, in industry, in education and within the public at large. Following the establishment of the virtual geoscience series, the 3rd Virtual Geoscience Conference (VGC 2018) explored the theme of immersive geoscience. The series aims to be a long-lasting forum to explore the exciting developments at the confluence of geomatics, computer science, visualisation and the variety of disciplines in the geosciences. The six peer-reviewed research papers forming this special issue highlight recent developments within the VGC series and VGC 2018 themes.

The use of three-dimensional (3-D), photo-textured representations of topography from laser scanning and photogrammetry is becoming increasingly common across the geosciences. This rapid adoption is driven by recent innovations in acquisition hardware, software automation, and sensor platforms, including unmanned aerial vehicles. In addition, fusion of surface geometry with imaging sensors, such as multispectral, hyperspectral, thermal, and ground-based radar, and geophysical methods creates complex and visual data sets that provide a fundamental spatial framework to address open geoscience research questions. Despite the current ease of acquiring and processing 3-D photo-textured models, the accessibility of tools for analyzing and presenting data remains problematic, characterized by steep learning curves and custom solutions for individual geoscience applications. Interpretation and measurement is essential for quantitative analysis of 3-D data sets, and qualitative methods are valuable for presentation purposes, for planning, and in education. This contribution presents LIME, a lightweight and high-performance 3-D software for interpreting and co-visualizing 3-D models and related image data. The software allows measurement and interpretation via digitizing in the 3-D scene. In addition, it features novel data integration and visualization of 3-D topography with image sources such as logs and interpretation panels, supplementary wavelength imagery, geophysical data sets, and georeferenced maps and images. High-quality visual output can be generated for dissemination to aid researchers with communication of their results. The motivation and an overview of the software are described, illustrated by example usage scenarios from outcrop geology, multi-sensor data fusion, and geophysical-geospatial data integration.