2.6

COLQUHOUN G.P., HUGHES K.S., DEYSSING L., BALLARD J.C., FOLKES C.B, PHILLIPS G., TROEDSON A.L. & FITZHERBERT J.A. 2023. New South Wales Seamless Geology dataset, version 2.6 [Digital Dataset]. Geological Survey of New South Wales, Department of Regional NSW, Maitland.

This data is part of the New South Wales Seamless Geology database, version 2.6, which is a statewide compilation of the best available digital geological mapping data in an internally consistent GIS format.

Dataset Authors:

Colquhoun, G.P.

Hughes, K.S.

Deyssing, L.

Ballard, J.C.

Phillips G.

Troedson, A.L.

Folkes C.B.

Fitzherbert J.A.

Scheduled updates to this dataset are planned as new data becomes available.

Disclaimer

The information contained in this product is based on knowledge and understanding at time of writing [May 2026].

Users should not rely solely on the information in this product in making decisions but should make their own inquiries and obtain professional advice. Users can check the currency of the information at the NSW Resources website.

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Copyright Statement

© State of New South Wales through the Department of Primary Industries and Regional Development (NSW Resources) 2026.

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Version 6.2 (Build 9200) ; Esri ArcGIS 10.4.0.5524

The dataset covers the land areas of New South Wales, Australia (including Lord Howe Island). A 10 km buffer into Queensland and Victoria is also included.

The NSW Seamless Geology Project team has compiled the best available geological data for the state into an internally consistent geodatabase. As part of the compilation process, contributing datasets were organised into a series of layers, or time slices, that represent the major lithotectonic subdivisions of the state’s geology. The data was then stitched/smoothed along existing map and dataset boundaries to create a seamless dynamic model of the geology of NSW. Important datasets and projects that contributed to the NSW Statewide Seamless Geology dataset are detailed below.

The Seamless Geology Project commenced in 2013 when merges of the best available datasets began to be assembled in the Statewide Geology Geodatabase (v.2) format. The source datasets for these merges are shown in the feature class “Seamless_V1_Source_Datasets” in this geodatabase. This merged dataset was divided into stratotectonic layers which were then edited by a small team of geologists, resolving edge-match issues and nomenclature problems between the geology of adjacent map sheets, and interpreting various layers under the cover of overlying layers. This produced a series of seamless geology layers which showed, for the first time, the actual distribution of rock units and structures, both in outcrop and under cover. These datasets were released progressively across the state as this work was completed, with three packages having been previously released; a Zone 56 dataset (Colquhoun, Phillips, Hughes, Deyssing, Fitzherbert & Troedson 2015), a Zone 54 dataset (Colquhoun, Phillips, Ballard, Hughes & Deyssing 2016) and a Zone 55 East dataset (Colquhoun, Deyssing, Ballard, Hughes & Troedson 2017). Zone 55 West was completed in mid-2018 but was not released as a separate dataset. Instead, the Zone 55 West data was merged with the previously released Seamless Geology datasets from the various zones and merged and harmonised to produce the first statewide Seamless Geology of NSW (version 1) in October 2018.

Updates to the Seamless Geology dataset have occurred every year since its release in 2018. These changes are detailed in a GS Report which can be accessed via the Download and links section above. Changes to the current version (v. 2.6) are detailed below:

What's new in Version 2.6 (May 2026)?

• Rockley–Gulgong Volcanic Belt (North) upgrade – the northern Rockley–Gulgong Volcanic Belt (RGVB) was comprehensively remapped during the 2024–26 RGVB project, integrating new fieldwork, age dating, and extensive georeferenced datasets to refine key Macquarie Arc units and adjacent Silurian and Ordovician sequences. This major upgrade unifies detailed legacy mapping with modern geophysics and high-resolution imagery to greatly enhance geological accuracy across the region.

• Broughton Island geology upgrade – the geology of Broughton Island was comprehensively

remapped by Neil Fraser (2025), leading to a major upgrade that included a new stratigraphic framework and the definition of the Gandja-baa Formation and its volcanic members, supported by petrography, geochemistry and a SHRIMP zircon age of 328 ± 2.6 Ma. Quaternary deposits were added separately using soil-landscape mapping and coastal imagery to complete the Seamless Geology update.

• Canbelego 1:100,000 map sheet area geology upgrade – a major update was made to the Canbelego 1:100,000 sheet, incorporating new reinterpretations of the Lachlan Orogen and Cenozoic Sedimentary Province based on geophysics, remote sensing and limited field mapping. The revisions refine structural relationships within the Girilambone and Kopyje groups and provide a more detailed depiction of regolith and alluvial systems, including newly mapped palaeochannels.

• Lord Howe Island – a small calcarenite outcrop on Lord Howe Island, part of the Neds Beach Formation (QP__n), has been documented through the karst studies of speleologist John Wylieand the Sydney Speleological Society.

• Moss Vale 1:100,000 map sheet area – several mapping updates were made in the Moss Vale 1:100,000 map sheet area based on suggestions from Steven Trigg, including adding a major railway-cutting void (centred on 150.2057194° -34.6795201°, GDA94) that exposes the Hawkesbury Sandstone, reshaping Cenozoic sediment boundaries, and incorporating new exposures of Snapper Point Formation and Grassy Gully Rhyolite along the Shoalhaven River(around 150.4071238° -34.8309831°, GDA94).

• Gunderbooka area changes – minor updates were made to 2 polygons in the Gunderbooka area following Liann Deyssing’s recommendations, reassigning one from the Narrama Formation to ungrouped Palaeozoic siltstone (145.7528999° -30.3493948°, GDA94) and the other from the Narrama Formation to the Ballast Formation (145.5580742° -30.9328485°, GDA94).

• Canbelego 1:100,000 map sheet area – minor revisions were made in the Canbelego 1:100,000 mapsheet area based on advice from Liann Deyssing and Steven Trigg, updating Chesney

Formation mapping to the Bee Conglomerate Member in its type area(146.0584197° -31.7528982°, GDA94).

• Rookery Fault, Wrightville 1:100,000 map sheet area – a small adjustment was made to the interpreted Rookery Fault (around 145.9673392° -31.5943303°, GDA94) in the Wrightville1:100,000 map sheet area, shifting it slightly north so it remains beneath Quaternary cover, consistent with the original 1985 mapping (Glen et al. 1985) rather than cropping out.

• Changes to the Meryula Formation, Cobar Basin – 2 updates were implemented for the Meryula Formation in version 2.6 of the NSW Seamless Geology: the Dederang Siltstone Member was removed and its polygons reassigned to undifferentiated Meryula Formation, and 24 polygons of unnamed basal conglomerate were reinterpreted and reassigned to the Drouin Conglomerate Member.

• Jugiong Shear Zone, Young Granodiorite – a duplicated representation of the Jugiong Shear Zone in version 2.5 of the Seamless Geology was corrected to keep it only in the faults layer and adjusting its position to align with the mapping of Stuart Smith (1990).

• Harrington area, New England Orogen and Cenozoic Sedimentary Province changes – several corrections were made to the Harrington area geology in version 2.6 after detailed fieldwork by Lindsay Gilligan, including converting mis mapped Cenozoic cover to basement outcrop, reassigning multiple polygons from the Cowangara Formation to the Permian Giro Beds, and adding a small Laurieton Conglomerate polygon where newly confirmed in quarry exposure.

• Seamless Geology updates to an unconformity between the Winduck and Mulga Downs groups –revisions were made by Steven Trigg to correct an exaggerated (cartographic enlargement)unconformity between the Winduck and Mulga Downs groups in the Wrightville 1:100,000 mapsheet area, with updated linework—validated by RA (Dick) Glen—extending to natural outcrop breaks and the reinterpretation of key formation boundaries and structural data for geological consistency.

• Updated rock unit descriptions – around 80 rock unit descriptions were updated using new, detailed information from the NSW Stratigraphic Units Database, aligning Seamless Geology attribution with the enhanced stratigraphic summaries now published in MinView.

• Rocky Creek Conglomerate, Clifden Formation, Lark Hill Formation and Caroda Formation –previously unnamed tuffs within the Rocky Creek Conglomerate, Clifden, Lark Hill and Caroda formations have been formally reassigned to their correct member units based on Roberts et al. (2003), bringing the Seamless Geology dataset into alignment with established Carboniferous stratigraphy as defined in ASUD.

• Misattribution updates − several polygons in the New England Orogen were corrected where units had been misattributed, with updates reassigning them to the appropriate formations or member units—Clifden Formation, Rocky Creek Conglomerate, Peri Rhyodacite Tuff Member, and Plagyan Ignimbrite Member—based on earlier departmental maps and Roberts et al. (2003).

• Lachlan Orogen and Permian–Mesozoic Igneous Province Changes − void polygons incorrectly derived from PMIP intrusions were merged into the surrounding Tannabutta Group after identifying the intrusives as sills, and a polygon (at 150.16487° -32.40441°, GDA94) was

reassigned to the Cenozoic Igneous Province as Airly Volcanics based on original mapping by Yoo (1998).

• Glenariff Granite – the Glenariff Granite’s type locality (146.5839° -30.7267°, GDA94) was located within an unassigned Silurian pluton polygon in Seamless Geology, conflicting with earlier interpretations by Hegarty (2017); this mismatch has now been corrected in the current dataset.

• Benolong Volcanic Suite – a polygon (148.5632470° -32.3967692°, GDA94) previously misattributed to the Dunoon Dacite was correctly reassigned to the Mesozoic trachyte of the Benolong Volcanic Suite, with the unit moved into the PMIP and the corresponding area voided from the Lachlan Orogen to match the Dubbo 1:100,000 mapping (Raymond et al. 2000).

• Permo-Triassic Basin (PTB) dyke – a Permo-Triassic Basin dyke near the Bayswater ash dam was extended ~3.5 km north-east following new advice from Conte Constante who is a local hydrogeologist.

• Reference updates – reference management in the seamless geology database was improved by consolidating all references into a central database. Each feature is now linked to its source using a PUB_ID, which populates the reference field in the attribute table. This creates a single source of truth, enables easy updates to reference formatting (currently author–date style), eliminates duplication across feature classes that use the same sources, and significantly improves the consistency and long-term management of reference information.

dataset

ISO 19139 Geographic Information - Metadata - Implementation Specification ISO 19139 Geographic Information - Metadata - Implementation Specification

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