Monday, 29 October 2012

SVP field trip: Basins of the Newark Supergroup

SVP field trips have earned a reputation as being high-quality and fascinating excursions guided by knowledgeable experts who understand the locations visited and their wider context within paleontological research. They often give the attendees access to museum collections and other behind-the-scenes insights at relevant institutions, which allow you to see great stuff not on public display, and they often take you to sites that might not always be accessible otherwise. This year's trip entitled Exploring Newark Supergroup Basins in North Carolina and Virginia was no exception.

The group study the exposures at the Virginia Solite Quarry.

 The Newark Supergroup was deposited in the Triassic as a series of rift basins extending from the Gulf to Canada, and North Carolina and Virginia have the southernmost surface exposures. We visited sub-basins in two of these basins over the three-day trip, the Dan River basin and the Deep River basin.

We were led by Andy Heckert (Appalacian State University), Nick Fraser (National Museums Scotland) and Vince Schneider (North Carolina of Natural Sciences), with on-site guidance at a couple of sites from Russ Patterson, a veteran local collector with unparalleled knowledge of these sites. We were driven by Jerry Reynolds, who is also a naturalist and was of great assistance to those of us who are unfamiliar with the flora and fauna of North Carolina and Virginia.

There were twenty-two of us on the trip, which meant most of us fitted into Jerry's bus with a couple of others in the van driven by Andy. We set off from the Marriott early on Sunday morning for three days of Triassic goodness, heading firstly to the Triangle quarry.

Unfortunately the Triangle Quarry owners had pulled our permission to enter the quarry the day before, so we had to be content with standing outside where the leaders gave an excellent introduction to the geology of the Newark Supergroup and showed us some of the fossils we would be looking for. We then headed back to the North Carolina Museum of Natural Sciences for a look in the collections (always a real treat) and then lunch.

A phytosaur tooth found by the author at the Little Egypt site.

 After eating we headed out to Jordan Lake to examine a small outcrop on the margin of the lake for around 15 minutes before heading off to the spoil heaps of the Little Egypt mine of the Sandford Fm, where we were guided by NC resident Russ Patterson, who gave us a description of the site, the works that had been here, what exposures were present and what to look for. This proved to be a most fruitful spot, and as we scraped away the accumulated detritus of the forest floor we exposed slabs we could split with hammers. We found phytosaur teeth and conchostracans in the shales, black widows and ring-necked snakes in hidey-holes.

The road construction site, with blocks blasted from the Crumnock Formation on the right.

 Our final stop that day was at a road construction site, where thousands of large boulders that had been blasted out of the Crumnock Fm during construction were piled up at the road margin, awaiting processing for hard-core. These boulders contained rare bones and occasional trace fossils, and we spent some time prospecting these piles of rocks. Several small bones were found, and I recorded some ichnofossils present in the hard, red sedimentary rock. Dinner that night was in the Cafe Vesuvio, and we all enjoyed a beer with a fine meal.

A quarry opened by some of the group at the Boren Clay pits.

Next day saw us team up with Russ again at the Boren Clay pits, an overgrown and partially flooded site (great for raisin’ skeeters!) with plant remains in the sandy upper layers of the outcrop of the Pekin Fm we were prospecting. We then set off for Alton Creek, which we reached after a short hike through the woods. This was a small outcrop of Crumnock Fm shales eroded by the creek, and here we found well-preserved conchostracans. We also found an Eastern Box Turtle, (Jerry thought it was a male, around 10 years old) who didn't appreciate the attention he was getting and subsequently closed his hinged plastron very tightly for the duration of our visit.

The rather charming Eastern Box Turtle found on at Alton Creek,
photographed just before he decided to shut out those pesky palaeontologists.

Then it was off to a road cutting on Highway 220, close to the Dan River. This site, with it's fine-grained and easily-split shales yielded a diverse range of fossils including ostracods, conchostracans, coprolites, vertebrate teeth and at least one fish scale.

Prospecting the cut close to the Dan River Bridge on highway 220.

We finished the day at the Virginia Museum of Natural History in Martinsville, where Alton Dooley led us around the excellent collections and who then fed and watered (beered?) us most satisfactorily before we retired to the characterful Dutch Inn.

Tranytrachelos tail found at the Virginia Solite Quarry.
Note the linear traces to the immediate right of the tail, which
appear to have been made when the tail moved over the sediment.

The Virginia Solite Quarry was our next location and this proved to be most exciting. Next to the site office is a large block containing ripple-marks and several Grallator trackways. The quarry section we were there to see consists of seventeen 20,000 year-old sedimentary cycles of the Upper Cowbranch Fm that are tilted at around 50 degrees. These grade from dark shales at the base of each cycle to massive sandstone beds at the top, and several beds are known to contain fossils. Some of these had been exposed in a trench excavated a few years previously and now sectioned by the quarry rim and most of the crew headed up to start digging there, however three of us stayed on the quarry floor where we searched the blocks for ichnofossils, the best of which were found by Beth Southwell and we interpreted as small tetrapod swim marks. However, the undoubted highlights of this site were the Tranytrachelos fossils found by several of the crew. This small, long-necked semi-aquatic tetrapod has bene found with soft tissue and whilst we didn’t spot these in our samples, after an hour or so of digging several partial specimens of this animal had be recovered.

A small tetrapod swim trace found at the Virginia Solite Quarry site.
We found several of these very small tracks in the fine-grained sediments of the quarry.

 Finally we headed back (via the VMNH) to Raleigh and the start of the SVP.

Big thanks to the trip leaders Andy, Vince and Nick, who proved to be excellent guides to this part of the Newark Supergroup. Extra kudos goes to Nick who stepped in for Paul Olsen who was supposed to lead but was prevented from doing due to family reasons. Thanks also to Alton at the Virginia Museum of Natural History, Jerry the driver and identifier of flora and fauna (as well as his fascinating explanation of how to handle venomous snakes) and Russ for being so generous with his extensive local knowledge. One of the great things about this trip was the amount of time we spent prospecting and digging and it really felt like we’d been doing good fieldwork during the three days we spent out and about.

Finally, a big thanks to the other attendees for being such excellent company for three days; as with Utah last year it feels like I've made good friends and I look forward to our next meeting, and perhaps working with them in the future.

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