Sunday, October 11, 2009

Summer Adventures Part 6: Fieldwork with Richard Hilton - the "North Coast Project" continued

So now comes part 6 of a 435 part series, better know a... sorry, I thought of Colbert when typing this first sentence. NO, I assure you, my summer wasn't that long. Shortly after I returned home for the summer, my family and I retired to Lake Tahoe for the 4th of July weekend. From there I took a beautiful drive up through the eastern side of the northern Sierras, skirting Mt. Lassen and Mt. Shasta, took I-5 up to Grants Pass, and then down to Crescent City, and further on up the coast from there to meet Richard Hilton, a paleontologist at Sierra College in Rocklin, and the writer of the lavishly illustrated Dinosaurs and other mesozoic reptiles of California (If I recall correctly, Richard is doing some fieldwork with fellow blogger/faithful visitor Neil Kelley, who is researching Triassic marine reptiles). Richard also brought along his close friend Paul Goldsmith, a cinematographer.

The beach here is safe enough to drive a regular 4x4 on, without modified low pressure tires.

Hilton typically goes prospecting for mesozoic marine tetrapods and dinosaurs in California, and Neogene mammal bearing localities in Nevada. However, he did some fieldwork in the Purisima Formation at Point Reyes in the 1960's, and thus he has a soft spot for marine mammal remains.

Sea lion femur in calcareous nodule.

After a few hours of looking, I finally spotted a concretion that looked like a fossil. Sure enough, there was some bone poking out of the sides. After a split second I was able to identify it as a sea lion (Eumetopias) femur. I got this puppy prepared just before SVP, and it is covered in fossil barnacles.

Richard Hilton fifty feet up a cliff of predominantly unconsolidated sand (read: not sandstone). This photo was taken nearly straight down.

Here I triumphantly show off the gigantic mysticete scapula fragment.

Later in the day, I found a huge chunk of bone (as float) about 80 feet up a cliff. However, after spending an hour and a half looking, the three of us couldn't find the rest of the bone - we found two more pieces which attach well, but nothing else in the loose talus, or in the exposure. Perhaps it was the last remnant of something big that had eroded out of the cliff, and the rest of it had already continued down to the river below. It is a very small chunk of a very large scapula (best guess); it is difficult to say exactly what it is because of its incompleteness. However, there are two important aspects to this fossil: 1) Mysticete bones are extremely rare at this outcrop, and rare from Pleistocene deposits in general (at least in North America); 2) there are two very large shark tooth bite marks on this bone, which are subparallel (which means that tooth spacing can be determined) ; one of these marks is nearly 5 inches long! That'll make a good short paper some day.

Richard Hilton ascends the cliff, looking for more fragments of the mysticete scapula.

Very strange trace fossils from this unit.
Closeup of the strange trace fossils.

One prominent feature of this unit I found on my first visit here over a year ago were the presence of bizarre, spiky trace fossils. I've seen cross-sections of these in the Purisima Formation, but this is the only other unit I've seen these in (which also happens to be a marine, Neogene, blue sandstone deposited in the lower shoreface). F.A. Perry hypothesized in his UCSC senior thesis that these were larval chambers for some invertebrate, potentially calianassid shrimp, and that the little spikes were larval escape structures. Here at this Oregon locality they are preserved in 3D, so study of them from this locality may prove much easier than in the Purisima.
Richard searching tirelessly for bones.

Displaying the mysticete scapula fragment at the end of the day.
Wisps of dust from the overlying late Pleistocene terrace pour down as veils over the shelly early Pleistocene deposits.

Other stops on our trip were the Miocene St. George Formation near Crescent City, the Pleistocene Moonstone Beach Formation, and the Plio-Pleistocene Centerville Beach section of the Wildcat Group. We returned empty handed from these other localities.


Neil said...

Just got back from the trip up to Shasta Lake with Dick, in fact. Had a bit more luck than you it appears - found loads of marine reptile bone within about 10 minutes of looking! We only managed to see about 1/1000th of the outcrop area it looks like we have some work cut out for us. We will probably head back up next spring, let me know if you are interested in joining us - the poison oak wasn't too bad, at least where we were...

Brian Lee Beatty said...

You and Neil are lucky, it is difficult to find fossil localities of marine vertebrates in New England. I'm trying to work out some marine-nonmarine correlations near here, including a place in Martha's Vineyard, but no one wants to let anyone collect in such expensive real estate here.... :-(

Robert Boessenecker said...


Awesome! If I have *time*, I might be able to join you guys. That's awesome that you guys found so much material! If there's very little poison oak, then I can totally manage...

Brian - I take it that's the Gay Head unit (can't remember if its an actual formation). A couple years ago I got an email about a Carcharocles megalodon tooth fragment from Maine, if you can believe that - the person actually thought it was a Troodon tooth, so my advisor at the time (Dave Varricchio) was emailed and he forwarded it to me. If I can find that email and the person who sent it... the promise of an as-yet unknown miocene unit in Main is very intriguing.

Yeah, I forgot how horrible a place New England was! Next to no marine vertebrate bearing units... This is partially why I'd like to end up at a university on the west coast, preferably in CA, near the coast.