|Beach exposure at west end of Ameracam Lane, west of Cranfield, near Greencastle, south Co.Down, showing interbedded thin to thick beds of silty calciturbidites and thin shales and calcareous siltstones of the Carlingford Limestone Group.|
|Site Type: ||Coastal section|
|Site Status: ||PASSI|
|District: ||Newry & Mourne District Council|
|Grid Reference: ||J25861065|
|Rock Age: ||Carboniferous (Arundian, Visean)|
|Rock Name: ||Carlingford Limestone Group|
|Rock Type: ||Limestone, Siltstone, Turbidite|
|Fossil Groups: ||Alga, Brachiopod, Coral, Foraminifera|
|Other interest: ||cross-bedding, Marine sediments|
Summary of site:
The Lane locality shows a small thickness of Carboniferous rocks that can be dated from their fossils and give evidence of the extent of the sea at that time.
Up to 1.5m of limestones, lime-rich mudstones and shales can be seen. The limestones were formed when sheets of sediment flowed as dense mixtures down small submarine slopes, mixing as they went, before settling, coarsest grains first. Storms or slope instability were the probable cause of these flows. Fossils of brachiopods, corals, crinoids with microscopic algae and foraminifera are frequent, indicating warm, shallow water conditions. Filled burrows are found in the shales.
Soldier’s Point to the west shows similar rocks but includes a sandstone. There is also a dolerite dyke.
Fossils at both localities indicate a middle Arundian age and the rocks suggest land close by.