Waterloo
Also within
Climate exposure
This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.
Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.
Geology & landscape
Geological Feature: Geological Fault, Igneous Intrusion, Rock Outcrop · Geological Period: Cretaceous, Jurassic, Triassic · Rock Type: Basalt, Limestone, Mudstone, Shale
Landscape processes: Coastal, Volcanic / Igneous
Description
Waterloo Jurassic stratigraphy, Triassic stratigraphy The area is of special scientific interest because of the sequence of Penarth Group, formerly Rhaetic, Upper Triassic, some 201 million years old and Lower Lias Lower Jurassic, 184-200 million years old strata, offering some of the best exposures in Ireland. Earlier Triassic Keuper and later Cretaceous strata are also present. During this period Ireland was positioned in sub-tropical latitudes, some 30°-40° north. Outcrop mainly takes the form of a wave-cut platform and former sea cliffs. The lowest beds southernmost seen are poorly-exposed red Mercia Mudstones of the Port More Formation. A short distance north 'Tea-Green Marls' of the Collin Glen Formation-actually greenish gray mudstones-are seen in the cliffs and on the foreshore. These mudstones are about 12m thick with numerous pseudo-pisoliths and pseudo-oolites, probable signs of low-grade metasomatism connected to the proximity of the Larne Lough Fault, here not far offshore. The Penarth Waterloo Mudstone succession recorded on the foreshore consists of a series of calcareous and non-calcareous mudstones and shales, together with minor sandstones. The Penarth holds an abundant marine bivalve fauna characterised by the presence of Rhaetavicula contorta and Protocardia rhaetica. In the Larne No 1 Borehole, about 2km to the south-west of Waterloo, the Penarth Group is about 20 m thick, but the succession at Waterloo totals only about 14 m. Two small faults seen on the foreshore may have cut out some of the Mudstone succession. At the top of the Waterloo Mudstones, there is an apparently conformable passage to the lowest beds of the Jurassic, the Psiloceras planorbis Zone of the Lower Lias. The lowest beds are shales and a thin limestone with a few fossils, including Protocardia cf. rhaetica and Pteromya tatei, but after about 7m the lithology changes to massive gray mudstones with abundant fossils, including the Zone fossil Psiloceras planorbis. These planorbis beds, totalling some 26m, can be followed as a series of small reefs up to the line of a Tertiary dolerite dyke which crosses the foreshore following the strike of the Lias beds. North-west of the dyke, a poorly exposed sequence of mudstones, rotten basalt and sheared strata suggests another fault zone trending north-east to south-west. Beyond this, the foreshore is heavily covered by loose boulders and only small, scattered exposures are seen. This shows that the strike swings to nearly north-south, while the dip remains about 25° to the west. West of the small low-water embayment, the lithology changes from the grey mudstones of the planorbis Zone, through an unproved thickness of mudstones of the liasicus Zone, to the alternating mudstones and thin limestones of the anqulata Zone. The foreshore, some 27m east of Waterloo Cottages, shows a section with nearly 7m of anqulata Zone beds, consisting principally of limestone, calcareous shale with Schlotheimia sp. in places, together with coprolites fossilised faecal pellets towards the base. Higher beds of more massive mudstones are seen in a small cliff immediately south of the Cottages. The planorbis, liasicus and anqulata Zones are within the Hettangian stratigraphic stage. About 150m north of these exposures, a small outcrop of a shelly crinoidal limestone and gray mudstones is seen among the boulders just east of Pebble Cottage, apparently separated by a fault from an exposure of gray shale and limestone with a northerly dip, about 20m north. Although no diagnostic fossils are presently evident in either outcrop, specimens in collections, apparently from these exposures, include Coroniceras Metaphioceras sp. and Arnioceras cf. bodleyi indicating the presence of the bucklandi and possibly the semicostatum Zones within the Sinemurian stratigraphical stage. https://www.daera-ni.gov.uk/publications/waterloo-assi