|Lifeboat House, Cushendall - small island south of||Antrim|
|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.|
|Site Type: ||Coastal section|
|Site Status: ||PASSI|
|District: ||Moyle District Council|
|Grid Reference: ||D24382676|
|Rock Age: ||Devonian (Upper Devonian)|
|Rock Name: ||Red Arch Formation|
|Rock Type: ||Conglomerate, Sand, Sandstone|
|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.