Tuesday, July 6, 2010

Cretaceous Oz: North by Northwest

Following field work in Victoria, Ruth and I went on holiday for our last few weeks in Australia, first to Sydney (New South Wales), then to Queensland. As Ruth and many other spouses/partners can attest, though, there’s one drawback with going on vacation with geologists or paleontologists. And that’s their insatiable drive to see more rocks or fossils. In that respect, then, Sydney seemed safe, being a big city with heaps of concrete and steel covering the good bits (geologically speaking). But Sydney also has great (and free!) museums, containing all of the items that catch the attention of the earth-inclined, and even has some outcrops of cross-bedded Triassic sandstone along its world-famous shorelines, including in front of the Sydney Opera House.

Why do photographs of the Sydney Opera House always omit the Triassic sandstone in front of it? This just goes to show you how even geologists can be temporarily distracted by dazzling architecture.

But how could a geologist not notice that the oldest brewpub in Australia – The Lord Nelson Brewery – is located in a part of Sydney called The Rocks? Out of a sense of scientific duty, we had to go there and sample a few of their brews, too.

A close-up of some of the local Triassic sandstone along a stairway in The Rocks part of Sydney, showing a transition from planar to rippled to some gorgeous convoluted bedding, the last a result of soft-sediment deformation, made before the sediment was cemented into rock. I can’t remember if this was seen and photographed before or after the visit to the brewery, which de facto means it was after.

Nonetheless, our main reason for going to Sydney was to view art, which was already plentiful, but made more so by a biannual art event named (oddly enough) The Biennale. Venues hosting art associated with this event were scattered throughout parts of the central business district (CBD) of Sydney, but most works were either at the Museum of Contemporary Art or on Cockatoo Island, which is located just north of the Sydney Harbor Bridge. For those of you who revel in using both sides of your brain and want to learn more about an artist’s perspective on this year’s artworks, please read Ruth’s take on it (written under her persona of Hallelujah Truth).

We also took in a few hours of the Australian Museum, which has a nicely done section on Australian indigenous cultures (including art styles of different regions), and the obligatory dinosaur hall, which seem to be required of all major natural-history museums. Nonetheless, I was pleased to see how the dinosaur-hall exhibit – which thankfully was not just about dinosaurs, but included other biota, even from outside of the Mesozoic Era – included much information based on the Cretaceous of both Victoria and Queensland.

A reconstruction of Qantassaurus intrepidus, the only dinosaur named after an airline (Qantas), but more importantly is a small ornithopod dinosaur that lived in southern Victoria during the Early Cretaceous Period, about 105 million years ago. Sadly, this detailed reproduction is mostly speculative, as this species is represented by only a few isolated bones, which also took considerable human labor to uncover.

A reconstruction of another small ornithopod from the Early Cretaceous of Victoria, Leaellynasaura amicagraphica. Unlike Qantassaurus, this dinosaur was named after a person (Leaellyn, daughter of paleontologists Tom Rich and Pat Vickers-Rich) and the friendship of the National Geographic Society, respectively. Also unlike Qantassaurus, Leaellynasaura is represented by a partial skull, as well as bones from below the skull.

Note the presence of a villainous raptorial claw entering the frame, about to victimize this poor, defenseless little dinosaur. Might be a good idea to duck into a burrow for safety, eh?

An ankylosaur is loose in the Australian Museum! What a waste! Oh, the humanity! The ankylosaur is Minmi, named in honor of creator spirits in indigenous cultures of northern Australia. Minmi is the most complete ankylosaur in Australia, and its skeleton was discovered in Early Cretaceous rocks of central Queensland, dating from about 95 million years ago.

As loyal readers know, I now have a little bit of experience with the Cretaceous rocks of Victoria after walking over a great amount of these (hmmm, some of those key words might be worked into the name for a blog some day). In contrast, I have much less experience with the Cretaceous of Queensland, which actually is far more extensive and produces vastly greater numbers of fossils than Victoria.

Now, I am not being disloyal to Victoria when I make such a statement: it’s just a fact, supported by the near-constant discovery and recovery of skeletons of large dinosaurs and marine reptiles. For example, last year the world learned about just how special Queensland dinosaurs were, when the Australian Age of Dinosaurs Centre unveiled three new species: two beautiful sauropods and one very nasty-looking theropod (and I mean “nasty” in a good, wholesome Janet-Jackson sort of way). Much, much more about those dinosaurs and the Centre will be discussed in a future entry.

But long before dinosaur bones were found in abundance in Queensland and new dinosaur species were described, people had found something even more important in central Queensland, and I say that with the fully biased opinion of an unrepentant ichnologist. That would be the Lark Quarry dinosaur tracksite, located about 110 kn (60 miles) south of Winton.

This tracksite is arguably one of the most important in the world (and yes, I will argue in favor of that designation, and yes, you will lose if you take up a contrary view). In a relatively small area on a single bedding plane are more than 3,000 dinosaur tracks preserved in natural relief. That in itself is remarkable, but the tracksite also records a few moments of dinosaurian behavior not interpreted from anywhere else in the world. More about that will be explored later, too.

So the following entries, based on our two weeks in Queensland, might be more aptly titled: The Great Cretaceous Drive, as not so much walking was done while we drove many kilometers in the outback. Fortunately for marital stability, there was a lot of paleontologically inspired art along the way too. So Ruth and I were able to combine our interests to each learn about why the Cretaceous of this part of Australia is also rich in stories that inspire our creative juices. So stay tuned for some juicy revelations, coming up soon!

The End of the Great Cretaceous Walk (Victoria Version)

(Field work along the Victoria coast ended last month, and now my wife – Ruth – and I are on holiday in Queensland, Australia. Strangely enough, we are still very much interacting with the Cretaceous in Queensland, so look for future entries dealing with that. The following is the last of the Victoria entries.)

The last day of field work in the Cretaceous of Victoria was on Wednesday, June 23, and it was mercifully laid-back and casual in comparison to our field experiences at Rotten Point and Dinosaur Cove the day before.

Mike Hall had left Apollo Bay the night before for home (which was in Melbourne), and Greg Denney was not joining us in the field, either. So it was just Tom Rich, my wife Ruth, and me going out on this fine day, one of the nicest weather-wise we had encountered during my month of field work in Victoria. Not surprisingly, we had some wild and wooly days during the course of a month: after all, it is winter there.

Our goals were to briefly scout two localities in the westernmost part of the Otway Ranges, which by happy coincidence were relatively close to The Twelve Apostles. This was Ruth’s third visit to this part of Victoria, yet she had not seen these natural wonders of Australia, the scenic centerpiece of the Great Ocean Road (albeit it was nowhere near the “center” of the drive, but more like the end of it if traveling from Melbourne). Tom insisted that Ruth would not miss The Twelve Apostles this time, a very gracious offer on his part, and justifiable for me as a geological-education stop. My students at Emory University can look forward to my showing them photos in their environmental geology class this upcoming September, whether they like it or not.

The Twelve Apostles, dwindling in number now but perhaps someday being joined by new seastacks through constant weathering and erosion. The ocean giveth, the ocean taketh away.

On the way to these seastacks, we first stopped at Moonlight Head, which was a bit difficult to pinpoint. In trying to find it, Tom had mistakenly conflated Moonlight Head with Wreck Beach, which led us to Moonlight Head, but it was not the same place he recalled, which we later found out was Wreck Beach. Wreck Beach he had visited only a few years ago, but he clearly remembered that 300+ steps were needed to reach the beach from the carpark. And of course, you had to climb back up those same steps if you wished to see the carpark again. (Life is full of choices, except when it’s not.)

Anyway, Moonlight Head was our first stop, and we parked the vehicle in a small space in front of a sign announcing that we were indeed at Moonlight Head.

Moonlight Head: The Sign. Note that the sign does not prohibit the use of wombats and explosives, a gross oversight by the park service, indeed.

We walked for only five minutes before stopping at a gorgeous overlook of the Victoria coast. Green coastal forest and scrub undulated downward to the sea, and far off in the distance were the tectonically tilted strata of the Otway Group, beseeching us to visit them and look for Cretaceous trace fossils.

Alas, its siren call fell on deaf ears, as our peals of laughter drowned it out. Our shared amusement was provoked by the thought of our walking for the next few hours downhill on a trail to such a faraway land – with no promise of trace fossils awaiting us there – then turning around and walking back up. Today was not the day for such athleticism or time consumption, especially with Wreck Bay and its 600+ steps happening later in the day. So with the GPS unit, I duly noted our position on the overlook, we took some photos, marveled at the scenery, and unceremoniously departed.

Wow, what fantastic Cretaceous outcrops! If only we felt like visiting them. Whoa, look at the time! Shouldn’t we be having a cuppa about now?

A little bit of backtracing in the vehicle brought us to a fork in the dirt road where we had originally taken a left, so now we took a right, which led to Wreck Beach. Fifteen minutes later, we arrived at a small carpark and got out to take a look. Yes, this was the place Tom had seen a few years before, and yes, the steps were there. A sign informed us of the precise number, which was 366, but for those people who like precision in their lives, more steps were required to walk from the vehicle to the start of the steps. Falsities abound when you live your life as an accountant.

Down we went, and quickly. Cretaceous sandstones and conglomerates were to my right and left, so I arbitrarily chose to go right. Cross-bedded sandstone was followed by more cross-bedded sandstone, which in turn was succeeded by cross-bedded sandstone. The lithological monotony was interrupted briefly by thin conglomerates, which were composed of broken bits of shale and fossil plant debris. After walking for about 20 minutes, no trace fossils made themselves apparent to me. All I saw was very nicely defined stratification, unsullied by burrows. A month of field work had led to my being able to discern which rocks were most likely to have trace fossils, and these were not those rocks. Ruth and Tom likewise saw no evidence of biological activity preserved in the rocks, either.

This space was left intentionally blank. That’s because I took no pictures of the rocks along Wreck Beach, out of protest at the lack of trace fossils there.

Soon we turned around, went back to the steps, and worked our way up, which took twice as long as going down, a result of that phenomenon known to some people as gravity (which is, after all, just a theory).

The way up from Wreck Beach, however many steps it might be.

Oh well – good exercise, fresh air, more rocks seen, and another locality in the Otway Ranges placed in the category of “There ain’t no trace fossils here.” And it was our last official stop in the Otways, and the last official stop of The Great Cretaceous Walk. After Wreck Beach, it was off to the Twelve Apostles (for which Ruth was grateful), and then to Melbourne for the night, before heading off to Sydney for a few days of rest, relaxation, and a big-city experience that was both interesting and jarring in its juxtaposition with our time along the Victoria coast.

But is this really the end? Not really, and I really mean that (for once). Following Sydney, Ruth and I made our way to Queensland for more vacation, but we passed through the Cretaceous of outback Queensland area, including a pilgrimage to Winton and the world-famous dinosaur tracksite, Lark Quarry, that is “only” 110 km (60 miles) south of town, as well as a visit to the very exciting Australian Age of Dinosaurs Centre just east of town. So keep tuned for a few more steps taken in The Great Cretaceous Walk in Australia. Will there be other years in Victoria, with more walking along Cretaceous outcrops? We shall see. In the meantime, on to New South Wales and Queensland!

Me, with my hand on the Tertiary Period and my feet in the Cretaceous Period at Dinosaur Cove, symbolizing how we oftentimes straddle great spans of time of which we cannot conceive nor comprehend. Also, I was trying really hard not to slip down the outcrop, and needed to hold onto something. Photo by Ruth Schowalter.