Geological folds are complex wave-like 3D deformation structures. The identification and measurement of characteristic geometric elements of folds (e.g., wavelength, amplitude, orientation of fold axis and fold axial plane) in rocks constitute core skills of field-based Earth scientists and prove to be challenging teaching topics for novice undergraduate geologists. This paper presents an immersive, interactive VR tool for visualising geological folds for educational purposes. We describe a novel geological folding visualisation system, designed to scaffold students in learning this complex spatial concept. Through a user-centered design with geologists, a new tool for digitally visualising geological folds for low financial and computational cost was developed. We describe its major components and visualisation approach, along with its interaction approach for providing fold visualisations. We further report findings from a usability testing (N=11) and report future design considerations.