Impact Glass Specimens from the Darwin Crater - Part I

Teardrops, Buttons, Balls, Boats and Dumbbells...

Just a few of the descriptive names for the array of shapes that tektites are found in. The study of these forms (morphology) helps provide clues to how the shapes were created. Each tektite form tells a story of how it was sculpted in mid-air as it dropped back to earth.

Less explored is the study of impact glass morphology. Impact glasses differ from tektites in slight ways. They usually have more inclusions, a slightly higher water content and are rarely found in aerodynamic forms. Also, the area they are found in (known as a strewn field) is much smaller.

Whereas the Australasian strewn field stretches for thousands of kilometers- the diameter of the Darwin Glass strewnfield is estimated to cover about 40 kilometers. This area is probably one of the best sites on the planet to compare and contrast the differences of form between impact glass and tektites.

The most common forms for Darwin Glass are twisted, irregular, globular masses. Looking like abstract black-green glass sculptures these are the ones that you're most likely to see for sale on the internet. Rarely, Darwin Glass can take on beautiful, aerodynamic shapes similar to tektites. These are the shapes I hope to showcase over the coming weeks.

Over the next couple of weeks, I will be providing book updates and I'll be posting some of the nicest pieces I found during my recent visit to Tasmania.  I welcome your comments about these shapes and would love to hear about unique examples from other collections.

One of the most interesting shapes I've found can best be described as a “U”-shape. Out of the many pieces of glass I found- only 5 showed anything approaching this form. Has any other impact site in the world produced anything close to this?

Measures 3.4 cm long x 2 cm wide and weighs 5 grams. Believe it or not- this was a surface find! I've never seen anything else like it! Have you?

Measures 4 cm x 2.2 cm and weighs 5.3 grams. This was one of the first pieces I found and is one of my favorites! Note that this piece also has a "U" shape that formed on its surface. I tried backlighting the specimen to show the flow lines emanating from the center. Reminiscent of "angel-wing" Moldavite.

Book Update #1
You may be wondering- How can someone write an entire book about a dull-colored and little-known stone locked away in one of the remotest rain forests on the planet?

It is a question that I asked over and over when I first got the idea to work on a book about tektites.  Unlike the hundreds of contemporary books written about brightly colored gemstones and diamonds- I can't wax poetic about human desire or color. Rather, there is a lot of new and interesting earth science to introduce to the general public.

This first book (of a series) is partly an introduction to impacts on earth and attempts to explain how and why impact glass is created. Juxtaposed with this scientific narrative is a travel story that explores Tasmania's unique ecology, cultural history and hundreds of years of scientific thought as it pertains to life on the island.

The more I discover about these stones the more fascinating they become. I hope that you'll share in this fascination that I, and many others, have developed for these very uniquely formed stones.

Kickstarter

I'm almost ready to launch a "kickstarter" campaign to help finance the many costs associated with the publication and professional editing of the book. If you're unfamiliar with kickstarter- its a type of crowdsource funding where I need to reach a monetary goal in order to be successfully funded. To help fund the publication of the book you'll be able to pre-order a copy of the book or purchase other unique and interesting rewards. Next blog post will have a link to the campaign.

2012 Darwin Crater Trip Report

Poison snakes. Leeches. Endless rain and knee-deep mud. The path to Tasmania's Darwin Crater is fringed with hazards. The old woods track leading down to the crater is unmaintained, thickly overgrown, crossed with downed trees and pocked with muddy bogs.

Very few people in the world have made it into Darwin Crater. If you want to be part of the elite few to visit this impact crater- the blog post that I've written out should be all the information you need to get there.

If you haven't come across the one other Darwin Crater trip report (from 2009)- check out this link:

http://kauscience.k12.hi.us/~ted/Craters/darwin.htm

There are some nice pictures of snakes and good images from google earth showing the crater.

Make sure you bring waterproof hiking boots, full rain gear (pants and parka), TASMAP's “Engineer #3831” 1:25000 scale map, and a GPS / Altimeter. The latter is needed to let you know when you are at the proper elevation. The crater is not readily discernible and the condition of the trail can make it a little difficult to know when you are in the right area. 

GETTING TO THE CRATER

The drive to the crater is very scenic. Give yourself plenty of time to explore the local area. Queenstown, the nearest town to the crater, is a worthy and useful stop. It has numerous hotels, a museum, petrol station, two grocery stores and a half dozen or so places to get a meal and a beer. There's an authentic feel to the town and tons of mining history everywhere.

You'll need a key to a forest service gate if you plan on driving to the crater parking area. Keep in mind that the Forestry Office, located on the outskirts of Queenstown, is open only from 8:30-9:30 AM. Be sure to give them a call if you need or want a key for gate access. If you don't manage to get a key- you can park nearby and have a 1km walk uphill to the trailhead.

From Queenstown, take Mount Jukes Road south towards the Darwin Dam on Lake Burberry for (approximately) 20-25 km. As you get closer, there are a couple of scenic pullovers for great photos:

Sunshine hits the peaks over Lake Burberry for a brief moment. White blossoms of leatherwood in the foreground make the best tasting honey in the world!

After descending towards the lake, you'll pass one camping area along the shores. It's very basic- pit toilets, a barbecue and picnic tables. The ground was really swampy when I was there. You wouldn't really want to pitch a tent there if it has been raining heavily. It's a fine spot if you have a camper van.

After passing the dam, the pavement ends and a very well-maintained unsealed road continues onward. You'll pass a dirt track on the right. This goes to the former town of Darwin. Today, nothing remains of this short-lived mining settlement. Then, you'll cross a bridge and the sign for the Franklin Gordon Rivers Wilderness. This is probably a good place to mention that, try as I did, I never found any Darwin Glass on or along the road. The road appears to have been resurfaced since the 2009 trip report.

Eventually, you'll reach a fork in the road. The left turn (Franklin River Rd.) goes up and towards the Darwin Crater. You'll reach the gate. It's a bit tricky and takes some awkward finagling to get the lock open and closed.

The trailhead is easy to find. It is on the left side of the road about 1 kilometer past the gate.

PATH TO THE CRATER

At first glance, the trail looks decent. However, in a little while, you'll be completely swallowed by the dense forest. There are a series of gentle ups and downs. For the first kilometer or two you'll generally gain elevation.

Typical trail conditions. Small patches of swampland are the only clearings you'll come across. Fallen trees along the entire way make for very slow progress along the 3.5km length.

Tussocks of Cutting Grass provides a welcome respite to the dense and overgrown brush.
Just don't touch the sharp, sand-papery leaves!

Eventually, the track cuts into a ridge and descends straight down for about a 100m. Portions can be steep and slippery. You'll know when you hit the area of the crater when these three things happen:

1. the track becomes an overgrown tangle completely impenetrable to man.

2. you wonder to yourself, “why did I try walking in this far?”.

3. mosquitoes start to bite you.

The crater elevation is about 175 meters while the high elevation along the trail is about 330 meters. If you're using a GPS- expect the elevations to be off due to thick forest cover and the fact that a handheld GPS doesn't produce ultra-accurate elevation readings. However, a GPS is still useful for measuring that 150 meter difference.

I found the hike back much quicker. Keep your eyes out for the forest's apex predator- the Spotted Quoll. They're common in the area and they let you know it with the abundant scats and tracks they leave all over the trail.

The rest of my time in the area was spent finding quality specimens of Darwin Glass- outside of the National Park and well away from the vicinity of the crater. That's an adventure in itself and I'm happy report that I found some amazing specimens very different from what is seen on the internet and on the collector's market. The next blog posting will get into detail about what I found.

If you have the time on the drive back down- take the turn onto the Bird River Road. Its at the fork where you make the turn onto the road to the Darwin Crater.

This well-maintained road consists of an old railroad cut through tall, dark thickets of man-ferns and rainforest. You'll end at a parking lot near a restored railroad bridge and a trail that will take you to Macquarie Harbor and the ghost town of East Pillinger. This gently sloping 15km (round trip) trail was one of the highlights of my visit to Tasmania and I highly recommend it. It more than makes up for the difficult visit to the crater!

Crumbling kiln walls. Nearly all that remains of East Pillinger.