FOSSIL SITES IN IRELAND - Section 3-4 - County Sligo - Streedagh Point - Mississippian

 Contents - Fossils sites in Ireland

Section 1-1 - Fossil collecting in Ireland
Section 1-2 - Where are the dinosaurs?
Section 1-3 - The good news

Section 2-1 - Precambrian/Cambrian
Section 2-2 - Ordovician
Section 2-3 - Silurian
Section 2-4 - Devonian
Section 2-5 - Carboniferous/Mississippian
Section 2-6 - Carboniferous/Pennsylvanian

Chapter 3 - Fossil sites in Ireland
Section 3-4 - County Sligo - Streedagh Point - Mississippian 

Resources 

Chapter 3 - Fossil sites in Ireland

by Jutta Kruse, version April 2025

This chapter gives examples of fossil specimens from several sites in Ireland. Each location is covered in a separate section. Full citations at Resources.

The locations are relatively easy to find, accessible and open to the public.

Visits to all locations are taken at your own risk. Coastal rocks can be very slippery at times, especially when wet. Winds, tides and large waves add risk factors. Please inform yourself on local conditions and always be safe.

Please leave fossils in Ireland where you find them. Search, find, identify, photograph and post them online, but do not specify the exact location where they were found to protect them from damage.

If you spot any errors or omissions, please let me know, Jutta at info@fossils.ie

Images ⓒ Jutta Kruse unless otherwise noted.


Section 3-4 - County Sligo - Streedagh Point - Mississippian

Fig. 3-4.1 - Location of Streedagh Point, county Sligo.


The prominent landmark of Benbulben in county Sligo comprises many of the Mississippian fossil-rich limestones and shales which also occur in the surrounding landscape, for example the Benbulben Shale Formation, the Glencar Limestone Formation and the Dartry Limestone Formation (GSI, Benbulben, undated). 

Fig. 3-4.2 - The mountain Benbulben is visible from many locations in county Sligo, including Streedagh Point. Image © Michael O'Connell 2022, used with permission of the author.


The Glencar Limestone Formation (Asbian, late Viséan, Mississippian) of county Sligo comprises numerous coral species (e.g. Siphonophyllia samsonensis, Siphondendron martini and Siphonodendron pauciradiale) as well as brachiopods, bryozoa, crinoids and foraminifera (McAteer & Parkes, 2004) (Holland & Sanders, 2009, pp 253-260).

The coastal locality in Sligo with perhaps the most impressive specimens of the solitary, rugose coral Siphonophyllia samsonensis is Streedagh Point (Somerville et al., 2009, pp 165-192) (GSI, Streedagh Point, undated). Some of the individual corals are up to 1m long and 10cm thick.

Fig. 3-4.3 - Corals Siphonophyllia samsonensis, Glencar Limestone Formation at Streedagh Point, county Sligo.


Fig. 3-4.4 - Corals Siphonophyllia samsonensis, Glencar Limestone Formation at Streedagh Point, county Sligo.


The typical 'elbow curvature' of the coral Siphonophyllia samsonensis is probably due to an adaptation of the corals to short-term changing living conditions at this location (pers. comm. Ian Sanders, 2022).

Fig. 3-4.5 - Corals Siphonophyllia samsonensis, Glencar Limestone Formation at Streedagh Point, county Sligo.


The daily, monthly and annual growth bands of corals reveal that years on Earth in the Palaeozoic had more months than today (for example, 13 months in the Devonian) and the Earth's axial rotation is continuously slowing down (Scrutton, 1965) (Wyse Jackson, 2019, pp 72-73).

Fig. 3-4.6 - Growth bands of Siphonophyllia samsonensis, Glencar Limestone Formation at Streedagh Point, county Sligo. Length of the specimen is 21cm.

Fig. 3-4.7 - Longitudinal section through a Siphonophyllia samsonensis, Glencar Limestone Formation at Streedagh Point, county Sligo.



Fig. 3-4.8 - graphic - transverse section of a rugose coral. Image credit: geological-digressions.com


Fig. 3-4.9 - Transverse sections of Siphonophyllia samsonensis, Glencar Limestone Formation at Streedagh Point, county Sligo.


Fig. 3-4.10 - Siphonodendron colony, Glencar Limestone Formation at Streedagh Point, county Sligo.


Fig. 3-4.11 - Brachiopod Gigantoproductus, Glencar Limestone Formation at Streedagh Point, county Sligo.