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Earth Science Conservation Review
| Hill's Port, The Gobbins - site of local interest | Antrim |
| Site number: | 755 | ||
| Locality Type: | Coastal section, Roadside section | Status: | local interest |
| Grid Reference: | J485971 Approximate | ||
| Google maps: | 54.80019,-5.69078 | ||
| County: | Antrim | Council area: | Mid & East Antrim Borough Council |
| Period: | Tertiary | ||
| Stages: | Palaeogene | ||
| Lithostrat: | Antrim Lava Group, Lower Basalt Formation | ||
| Site Description | |
|---|---|
| Highlights: | |
Roadcut and sea-cliff exposures of amygdaloidal Lower Basalt Formation (Palaeogene) containing unusual zeolite minerals are exposed at Hill’s Port at the south end of The Gobbins cliffs on Island Magee. This site is the type locality for the zeolite mineral gobbinsite. | |
| Description: | |
The lay-by on the Gobbins Road due east of Hill’s Port, opposite the lane descending to the shore, is a convenient place to park and is also of mineralogical interest. The 6m high roadcut exposes the uppermost part of a basaltic flow within the Lower Basalt Formation (Palaeogene), which is increasingly amygdaloidal upwards and is overlain by the basal massive part (1m thick) of another flow. Natrolite and analcite are the dominant zeolite species, and samples can be obtained from loose boulders and cobbles at the base of the cliffs. The shore at Hill’s Port is accessible on foot. The Gobbins cliff and waterfall form impressive features north of Hill’s Port. By going through the short tunnel next to the carving of ‘Gobbins Path’ and following the path around a small headland, a rocky bay is reached where the path has been destroyed by erosion and landslips. Boulders in this area (some 10m2 in extent) are of amygdaloidal basalt containing a wide variety of zeolite minerals: analcime, chabazite, cowlesite, gonnardite, gobbinsite, heulandite, levyne and mesolite have been observed. Some vesicles also contain calcite and travertine. | |
| Importance: | |
The site has some mineralogical significance due to the mineral assemblage within the basalts and the fact that this site is the type locality of the zeolite mineral gobbinsite. | |
| Interpretation: | |
Zeolite minerals are alkali-bearing aluminosilicates that contain chemically-bound water molecules (Tschernich, 1992). Their occurrence in amygdales is characteristic of flood basalt lava piles such as in the Irish and British Tertiary Province and Iceland. Walker (1960 and earlier papers) studied the distribution of zeolite mineral species in the lava piles of Ireland and Iceland, and was the first to demonstrate that zeolite mineralogy related to (a) rock type i.e. whether the host basalt is olivine-bearing or tholeiitic, and (b) depth in the lava pile, i.e. the temperature attained during hydrothermal alteration. The zeolite mineral assemblage at Hill’s Port is characteristic of olivine basalt alteration within the scolecite-mesolite zone (Walker, 1960), whereas the roadcut exposures are probably within the topographically higher (lower temperature) analcime zone. Although analcime-zone zeolite-bearing basalts are widely distributed in County Antrim, Hill’s Port provides a reasonably accessible site where specimen material is abundant. The zeolite minerals gobbinsite (named after The Gobbins cliffs) and gonnardite are of restricted occurrence elsewhere. | |
| Notes: | |
This is an area of spectacular coastal scenery and historical interest. See also ESCR Key Site 527 - Hill's Port, The Gobbins, Island Magee [Mineralogy and Metallogenesis Block]. | |
| Keywords | |
|---|---|
| Minerals: | Analcime, Calcite, Chabazite, Gobbinsite, Natrolite, Zeolites, Heulandite, Levyne, Cowlesite, Mesolite, Gonnardite, Travertine |
| Rocks: | Basalt |
| Structures: | amygdales |
| Access | |
|---|---|
| Approach: | This site comprises roadcut and seacliff exposures at The Gobbins, Islandmagee. |
| Record type: | SLNCI Report | ||
| Entered by: | E M Porter | ||
| Last updated: | 09/10/03 | ||
| Enlander, I., Dempster, M. & Doughty, P., 2026. Hill's Port, The Gobbins - site of local interest, County Antrim, site details. [In] Earth Science Conservation Review. https://www.habitas.org.uk/escr/site.php?item=755. Accessed on 2026-11-06. |
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