For the third time this summer John and I ran a successful and enjoyable field weekend in Northumberland aimed at first year OU students with an interest in geology and ecology (see Fieldwork versus virtual reality). Highlights of our ecology day, learning how to survey plants and lichens on Cullernose Point, included cabaret provided by a pod of dolphins cavorting just a few hundred metres offshore.
Students surveying the vegetation at Sea Houses
Our second day was spent looking at the early Carboniferous limestones and sandstones which make up many of the layers of spectacularly-folded and tilted sedimentary rocks around Howick Bay and the Whin sill which intrudes into these.
The Whin sill of Cullernose point behind the whale-back folds of Swine Den
Some of these sedimentary layers are rich in fossils – both trace fossils of burrowing animals such as Eione and fossil crinoids, corals and plant material.
Eione miliforme burrows in sandstone at Howick Bay
Tiny crinoid stem fragment in the Acre limestone at Howick
However this time we also found another fossil, intriguingly like the bryozoan fossils we had found just a month or so earlier in the Guryul area of Kashmir (see Back to Guryul).
Our mystery fossil in the sandstone at Howick Bay
Bryozoan (Fenestella sp.?) in sandy limestones of the Permian Zewan formation, Guryul
The Guryul site is of particular interest to geologists for being one of the very few places in the world where the oldest Triassic sediments can be seen lying directly on top of the youngest Permian ones. The Permian/Triassic boundary was around 250 million years ago so these rocks are much younger than those at Howick but it would not be surprising to find bryozoans at both. These colonial filter feeders were the last major phylum to appear in the fossil record, some 485 million years ago in the early Ordovician, but were common throughout the Paleozoic era and there are still some 4000 extant species today, mostly inhabiting marine environments. However it now looks as if our ‘mystery fossil’ is probably actually a colonial rugose coral, perhaps Lithostrotion.
Another Bryozoan, possibly Penniretepora sp., also in rocks of the Zewan formation
We’ll be running a trip to Howick Bay again on June 10-12 next year as well as another trip to Kashmir and Ladakh from July 30. If you’re interested in finding out more about either trip, e-mail me on firstname.lastname@example.org.