Irish Geo Travels – Northern Ireland

Traveling to Ireland has been something I’ve wanted to do. So, when the opportunity came up to go to Scotland, I couldn’t leave the general area without seeing at least some of both Northern Ireland and the Republic of Ireland. I only made it as far south as Dublin, but I guess on the positive side, that leaves many places that I need to visit on a future trip.

I flew from Glasgow into Dublin, rented a car, and first headed for Northern Ireland which is the subject of this blog. The causeway coastal route in Northern Ireland (from the North Channel coast eastward to the Irish Sea coastline) is a drive that I wanted to try. I ended up driving only about half of it – from Ballycastle east to Port Stewart because I spent so much time stopping to look at rocks and scenery.

The area that I drove through is a part of the Causeway coastline that cuts into the Antrim lava plateau. Beginning about 62 million years ago and continuing for several million years, extensive volcanic activity associated with the opening of the north Atlantic Ocean occurred here.  In fact, igneous activity was so extensive in the nascent north Atlantic area, that the Antrim plateau basalts are only a small part of the North Atlantic Igneous Province, which is centered on Iceland.  But – coming back more locally to the Antrim area, basaltic lava here intruded into Cretaceous marine strata, mainly chalk beds (which makes a striking visual contrast along the coastline). As noted on a Queen’s University Belfast website for the Giant’s Causeway:

The total area of these flows is now much reduced compared to their original extent, but they still constitute, at 3,800km2, Europe’s most extensive lava field. Traditionally the lavas of the Antrim Lava Group have been divided into three main phases of activity, separated by two extended periods of quiescence or limited, local activity.

The two areas that I spent most time at during my coastal causeway drive are the Carrick-a-rede Bridge and the Giant’s Causeway. These areas are developed within the Lower and Middle Basalts of the Antrim Lava Group and contain an Inter-basaltic Bed of reddish-weathered regolith and paleosols. A photo tour of the two areas are shown below –

Carrick-a-Rede Rope Bridge

A rope bridge connects the mainland with Carrick-a- Rede island. The first rope bridge was built in 1755 to facilitate fishing of Atlantic salmon. The salmon fishery has since died out, but the bridge is maintained as part of National Trust lands.

The Coastal Highway is cut into the Antrim Plateau where Paleocene basalt overlies Cretaceous chalk strata. The Lower and Middle Basalts of the Antrim Lava Group are in this area separated by a reddish-colored paleosol zone.
The hike to the Carrick-a-Rede Bridge goes over Paleocene basalt of the Antrim Lava Group.
A closer view of bridge – not too much wind when I visited, so it was a pleasant walk across the bridge.

Giant’s Causeway:

The Giant’s Causeway is a UNESCO World Heritage Site. As noted on its UNESCO website:

The Giant’s Causeway lies at the foot of the basalt cliffs along the sea coast on the edge of the Antrim plateau in Northern Ireland. It is made up of some 40,000 massive black basalt columns sticking out of the sea. The dramatic sight has inspired legends of giants striding over the sea to Scotland.

UNESCO World Heritage Site signage at the entrance to the Giant’s Causeway.
A Giant’s Causeway marker – This area was inscribed as a World Heritage site in 1986.
The paleosol zone of the lower Inter-Basaltic Bed exposed on the road to the Giant’s Causeway.
The onion skin basalt rocks at Windy Gap, on the road to the Giant’s Causeway basalt columns. These rocks have undergone much spheroidal weathering.
Causeway basalt columns…
More columns…
…and more columns. Halfway up the far slope is the reddish-colored lower inter-Basaltic bed that separates the Lower Basalt from the Middle Basalt of the Antrim Lava Group.

Cenozoic Sequence Stratigraphy of Southwestern Montana

Much of my research has been focused on Cenozoic sequence stratigraphy of continental basin-fill in southwestern Montana. This approach to the stratigraphy of continental deposits has facilitated correlation of stratigraphic units both within and among the various basins of this area. I recently gave a talk about my work in this area at Montana Tech of the University of Montana. Here’s the You Tube version of my talk:

The Field Season Is Going Strong in Southwestern Montana

My field season is in full swing. I recently spent time with students from the Webb Schools in Claremont, CA, during their annual sojourn to southwestern Montana. We prospected a few Tertiary localities, with the students making some good fossil mammal and fossil invertebrate finds. We were also extremely lucky to have a southwest Montana landowner give us a tour of a buffalo jump that is on his land. The following photos are from our various fossil site and buffalo jump field adventures.

Tertiary fossil snails (about 25 My in age) at one locality captured the interest of students. Once one snail was found, everyone was intent on finding more.
Bob Haseman talks about a buffalo jump in the Toston Valley. He is standing by one of the many tepee rings associated with the jump site.
Bob Haseman talks about a buffalo jump in the Toston Valley of southwestern Montana. He is standing by one of the many tepee rings associated with the jump site. The small boulders on the surface between Bob and the students are part of a tepee ring.
Webb School students hiking up to the "Looking-Out" site associated with the buffalo jump. A eagle catchment area is immediately below the highest point of the "Looking-Out" site.
Webb School students hiked up to the “Looking-Out” site associated with the buffalo jump. A eagle catchment area is immediately below the highest point of the “Looking-Out” site.
The eagle catchment area is a shallow depression where a person would hide beneath brush awaiting the approach of an eagle. A nearby animal carcass would aid the quest to capture a eagle which was then used for its feathers.
Chadronian (about 36 Ma) age rocks yielded a few brontothere teeth and bone fragments.
Chadronian (about 36 My in age) rocks near Three Forks, Montana yielded a few brontothere teeth and bone fragments for the curious students.
Chadronian strata in this area contain brown to reddish, popcorn textured floodplain deposits and whitish-colored fine-sand channel deposits.
Chadronian strata in this area consist of brown to reddish popcorn-textured floodplain deposits that contain paleosols and whitish-colored fine-sand channel deposits.