This monograph tests the hypothesis that ecological variance across South Devon is primarily governed by geological basement, with Torquay and the English Riviera Global Geopark forming the coastal carbonate-red-bed end member and Dartmoor National Park forming the upland granite-peat end member. The study synthesizes geomorphology, lithostratigraphy, hydrology, soil science, marine ecology, upland conservation, and climate-risk analysis across a transect extending from Tor Bay's sheltered littoral zone to the exposed Dartmoor massif. The methodology is comparative and systems-based: published geological mapping, cave and tor geomorphology, protected-area documentation, marine conservation designations, habitat inventories, peatland restoration studies, and field-observable diagnostic criteria are integrated into a single interpretive framework. Torquay is treated as a coastal basin where Devonian reef limestones, slates, Permian red beds, and Quaternary karst archives generate alkaline soils, erosional cliff niches, cave sediment records, and biologically rich shore-platform and seagrass systems. Dartmoor is treated as an intrusive upland where Early Permian granite, boron-rich mineral assemblages, periglacial tor evolution, acidic soils, high rainfall, and peat-filled basins create a contrasting ecological regime of blanket bog, heathland, clitter lichen communities, clean headwater streams, and ancient Atlantic oakwood fragments. The analysis finds that geology is not a passive backdrop but an active environmental control. Bedrock chemistry regulates soil pH and nutrient availability; structural fabric governs hydrological pathways and erosion forms; topography changes rainfall interception and microclimate; and historic land use amplifies or suppresses the biological niches made possible by substrate. The Torquay coast supports high beta diversity in compressed gradients between limestone grassland, caves, intertidal reef, and sandy bay habitats, but is exposed to tourism, urban runoff, anchoring, and sea-level rise. Dartmoor supports specialized upland species and large hydrological carbon stores, but its condition depends on grazing intensity, peat rewetting, wildfire prevention, and climate-sensitive water balance. The central conclusion is that conservation planning must couple geodiversity with biodiversity, treating Torquay and Dartmoor as linked components of one South Devon environmental system rather than as isolated scenic landscapes. This integrated framing also defines practical monitoring priorities for resilient restoration, from cave sediments and seagrass beds to peat hydrology, grazing mosaics, river corridors, and future decades.