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Lifeboat House, Cushendall - small island south ofAntrim
Small 'island' 200m S of Lifeboat House, Cushendall, Co.Antrim, showing Unconformity A of Simon (1984) separating conglomerates of Units 1 and 2 (top) of Red Arch Formation; Wilson (1953) thought this separated Upper Palaeozoic from Lower Mesozoic rocks.
Summary Full report
Site Type: Coastal section
Site Status: PASSI
District: Moyle District Council
Grid Reference: D24382676
Rocks
Rock Age: Devonian (Upper Devonian)
Rock Name: Red Arch Formation
Rock Type: Conglomerate, Sand, Sandstone
Interest
Other interest: No data, Unconformity, braided stream

Summary of site:

The outcrops along this stretch of coastline show a clear unconformity (a break in time) between units 1 and 2 of these supposed Devonian rocks. To place them in context, the account for Key Site 1148 ‘Devonian - Red Arch Formation; Cushendall to Red Arch, Glenariff’ should be read with this one. The lowest rocks, forming the top of Unit 1, are red, pebbly sandstones and fine to medium grained conglomerates formed in transitory braided streams draining from debris cones banked against uplands in a hot desert. Unit 2 is separated from Unit 1 by the unconformity and there is a difference in the dip (tilt) of the beds between the two of 15-20º. Unit 2 is 20m thick and consists of coarse, red cobble conglomerate with the cobbles in direct contact with each other, probably part of a later debris cone swept out of an upland valley by a flash flood following a violent rain storm.

These shore outcrops are the best exposures of the unconformity and should be preserved.


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