THOMAS SOPWITH’S BOOK OF GEOLOGIC MODELS AND THE ORIGINS OF 3D SPATIAL THINKING SKILLS

In 1841, Thomas Sopwith (1803–1879) began producing sets of beautiful wooden geologic models bound in handsome book-like cases. Produced in limited quantities, these models represent the first widely available instructional aids designed to help students develop 3D spatial thinking skills. Despite their pedagogical, artistic, and scientific significance, knowledge of Sopwith’s models is rare outside the UK despite the enthusiastic support of contemporaries, including William Buckland and Charles Lyell. We present a series of high-resolution, digital SKETCHFAB 3D renderings made from a complete set of blocks using the improved focus-picking, double-masking photogrammetric workflow, after Hollister et al. (2020). This approach combines lighting, photographic, and post-processing techniques to generate digital models that capture large depth-of-field variances so they are accurate even at sub-millimeter magnifications. Early 19th century practitioners of the new science of geology developed the visual vocabulary and techniques needed to observe, interpret, and communicate geologic phenomena through the use of 2D geologic maps and vertical sections. The practical applications of maps and sections delineating the distribution of geologic units to mining, surveying, and engineering quickly led to the need to use spatial thinking skills to extrapolate 3D subsurface relationships. While Sopwith is not the first to experiment with block models, his training as a cabinet maker, surveying experience, observations of subsurface mine workings, and interest in isometric projections made him ideally suited for creating truly effective representations of geologically admissible subsurface relationships. Sopwith’s blocks are the first accurate illustrations of cross-cutting relationships, arrays of synthetic and antithetic normal faults, and V-shaped map patterns created by interactions between topography and flat or homoclinal sequences of dipping strata. His models are constructed from 27 separate boards of different hardwood species with thicknesses scaled to represent the stratigraphy of the coal and lead mining districts in northern England. Models were produced in hand-sample sizes and accompanied by a book containing detailed descriptions of the geology captured in each block.