This dataset contains a petrel project and associated horizon grid, surface, and point data interpreted using the Glencoe 3D seismic reflection survey as part of the NERC Pushing the Frontiers MAGMA (Magma Accommodation and Ground Movement Analysis) project led by Dr Craig Magee (c.magee@leeds.ac.uk) between 10/23 to 03/27. Specifically, we use this data to map the top and base reflections of a thick sill and the corresponding top of an overlying forced fold. This data accompanies the published manuscript (see also its supplementary data): Magee, C., Ebmeier, S.K. and Hickey, J., 2026. Testing volcano deformation models against 3D seismic reflection imagery of ancient intrusions. Journal of Geophysical Research: Solid Earth, 131(2), p.e2025JB032007.https://doi.org/10.1029/2025JB032007 The Glencoe 3D seismic reflection survey and associated well data used in this project can be accessed through either through Geoscience Australia (http://www.ga.gov.au/nopims) or the NGDC at: https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html?simpleText=glencoe#item172421, record number 172421