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Slieve Gullion Ring - Mullaghbawn NorthArmagh
Exposure in north Cashel district, west of Mullaghbawn village, Co. Armagh; darker coloured Porphyritic Felsite on right in contact with lighter coloured Porphyritic Granophyre.
Summary Full report
Site Type: Roadside section
Site Status: PASSI
District: Newry & Mourne District Council
Grid Reference: H977187
Rocks
Rock Age: Tertiary (Palaeogene)
Rock Name: Lislea Granophyre, Porphyritic Felsite, Slieve Gullion Complex
Rock Type: Agglomerate, Felsite, Granophyre, Trachyte
Interest
Other interest: ring-dyke, ring-fault, volcanic vent, Intrusion

Summary of site:

The context of this site is described in the Slieve Gullion Ring Overview, site 1118.

North and south of the minor road, over a distance of 1.5 km the earliest rocks intruded into the ring can be seen and their junction with the rocks of the main intrusion that followed. The first rocks were porphyritic (large crystals in a fine groundmass) felsite associated with the vent agglomerate, evidence of the explosive violence of the eruption. Further north the contact between the felsite and the porphyritic granophyre of the main intrusion is clearly exposed and it is obvious that the granophyre was later because there is clear evidence that it chilled against the felsite and veined it along fractures. South of the road there are further exposures and masses of trachyte, an intermediate rock (between granite and basalt in composition) are recognisable in the agglomerate. Its contact with the felsite can be seen here and, again, the contact of the felsite with the granophyre. This excellent and accessible site is important because it establishes the age relationships of the two main rock types intruded into the ring and the agglomerates are a record of the violence of the initial volcanic blast, all essential to our understanding of the evolution of the Slieve Gullion Ring complex.


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