NSW Seamless Geology Version 2.5

The NSW Seamless Geology Project was originally a five-year initiative of the Geological Survey of New South Wales which commenced in late 2013 and aimed to provide a statewide compilation of the best available digital geological mapping data in an internally consistent format. The overarching aims of the NSW Seamless Geology Project were to: (i) compile the different original scales, formats and rock unit naming conventions into a consistent, statewide format; (ii) edge-match the geology across existing map sheets; and (iii) interpret the basement geology under cover. The resulting geodatabase comprises a series of layers which include: (i) solid basement geology; (ii) cover rocks (defined as undeformed and unmetamorphosed); (iii) Mesozoic igneous rocks; and (iv) Cenozoic sedimentary and igneous rocks. Due to the size of the project, the work was divided into UTM zones, starting in the east with Zone 56, then moving west to Zone 54, and finishing with Zone 55. The western half of Zone 55 was completed in 2018, after which the results were merged with the previously completed Zones to produce version 1 of the NSW Seamless Geology dataset. Completion of this stage saw the end of phase 1 of the Seamless Geology Project, but it is intended that the Seamless Geology dataset will be continually updated and refined as new digital geological mapping data becomes available. Updates to the Seamless Geology dataset generally occur on an annual basis. Version 2.5 is the 7th major update to the NSW Seamless Geology and was released in May 2025. This release includes: a new layer to capture Cenozoic ‘sub-basaltic gravels and deep leads’; significant upgrades to the mapping of numerous areas in the Lachlan Orogen (particularly the Coolac Serpentinite Belt, Gilmore Fault Zone, and the Eden-Merimbula area); a major update to the mapping of the Gunderbooka 1:100,000 map sheet area and the Port Macquarie–Laurieton area; and attribute updates, data additions, and minor error fixes to all layers. NOTE: A substantial amount of overlay, erase and intersect geoprocessing of the original multi-layered Seamless Geology was undertaken to produce the single layer surface NSW Seamless Geology dataset. Due to small tolerance differences between different layers in the Seamless Geology dataset, this has, in some places, created small “sliver” polygons between boundaries common to more than one layer of the original multi-layered NSW Seamless Geology. This is a known issue with the current single layer Seamless Geology dataset and while some attempt has been made to resolve these issues, a number of small “sliver” polygons remain. Users are cautioned to be aware of this problem when using this dataset at high zoom levels (ie. under 1:1,000 scale) and to refer to the full Seamless Geology dataset for clarification.