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Carricklongfield QuarryTyrone
Carricklongfield Quarry, 5km ENE of Aughnacloy, Co. Tyrone, exposes Carrickaness Sandstone Formation.
Summary Full report
Site Type: Quarry (disused)
Site Status: PASSI
District: Dungannon District Council
Grid Reference: H716544
Rock Age: Carboniferous (Visean)
Rock Name: Carrickaness Sandstone Formation, Tyrone Group
Rock Type: Sand, Sandstone
Fossil Groups: Alga, Brachiopod, Crinoid
Other interest: No data, Marine sediments

Summary of site:

Since the full report for Carricklongfield Quarry was written, new relative datings of rocks in this area have been conducted, based largely on microscopic fossils. Following from this work, the geology of the area has been revised and the sandstone in the quarry is no longer considered to be part of the Carrickaness Sandstone Formation. It is now known to belong to the Aughnacloy Sandstone Formation.

In the quarry, up to 12m of well bedded, often finely laminated pale grey to pale brown lime-rich coarse sandstone can be seen, with ooliths (see glossary) and obvious broken shelly material in some beds. Major bedding planes are more widely spaced at around 2m. Recognisable fossil algae and large lamp shells of a group called the gigantoproductids are also found, suggesting an Asbian age for the sandstone of around 338 million years. The fossils all indicate that the sandstone was formed in a marine environment and the broken shelly material, the ooliths and the fine laminations are all consistent with fairly high energy winnowing in shallow water. Such deposits are usual on inshore shoals and the presence of a thin coal seam in the same sandstone at the abandoned quarry at Legane Lough (2.5km to the east) shows that the sands dried out long enough for forests to become established. It is worth noting that the Aughnacloy Sandstone has been used extensively in the area as a building stone and has proved durable with excellent weathering properties. The joints cutting across individual beds are widely spaced, permitting wide window sills and imposing steps to be dressed (a particularly desirable characteristic for masons). The quarry is the finest example of the Aughnacloy Sandstone Formation available and should be protected. Its threats are those common to all abandoned quarries, particularly landfill and dumping.

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