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Tasmanian Field Studies

Geology and Natural History of Tasmania and The Great Barrier Reef

Geosciences/Environmental Studies 295

June 7 - July 1, 2013

Eugene Domack, the Joel W. Johnson Family Professor of Environmental Studies, led a group of 18 Hamilton students to Tasmania for a three-week field excursion that highlighted the geology, botany and natural history of the region. Their field work focused on the geology of the southern continents, economic resources and wilderness conservation and included a one-week trip to the Great Barrier Reef. This trip was subsidized by the Joel W. Johnson Family Professorship in Environmental Studies and the Donald Potter Endowment in Geology, and was offered as part of Hamilton’s participation in the International Antarctic Institute.

The students who participated in the course submitted the following photos and journal entries to summarize their field work.

June 26 - Hellyer Gorge
By Joseph Coons

Today we left our cabins in the Cradle Mountain National Park and headed towards the north shore of Tasmania. On the way we stopped at a number of areas that exhibited Parmeener Supergroup geology.

The first was at the Hellyer Gorge, which was stratiagraphically located at the base of this formation. Here we found Diamictite that was over 500 meters thick, which made it the largest in the state. There was also evidence of true tillite deposition, which occurs with the progression of glaciers. In this case, the ice sheets that had started on the west coast of Tasmania moved inland until they were diverted north by the Cradle Mountain range. As a result, boulder pavements with isodirectional striations and foliations from ice stress formed. As well, there were many examples of marine mud and shale, as well as laquestrine deposits from lake beds. These varvites and rhythmites contained a number of insect fossils and seed ferns. 

After looking at this we progressed to another location that viewed the upper sections of the Parmeener groups. Here, we explored the evolution of fossil plants. Specifically, we observed fossil Glossopteris leaves and compared them to Cordiate leaves. The Cordiates have leaves with parallel veins while the Glosopteris has leaves that contain veins that branch off a larger central vein. In the Mesozoic, as the climate transitioned to more arid temperatures, there was an evolutionary shift to the Cordiate leaves, which required less energy to maintain.

 

June 25, 2013
By Caroline Gregory '14

Today, we left behind the views of the Bass Strait and headed south to Mole Creek. Our first stop was a retired tasmanite oil shale mine. Tasmanite is shale with very high concentrations of small algal cysts (organic content >20%). It is colored light gray to yellow-brown when it is fresh, but gradually weathers to red-brown. Because the tasmanite was not buried deeply enough to naturally produce oil, in order to make usable products, the rock must be heated in a device called a retort. In the past, the cost of labor to heat the rock outweighed the profit that could be gained from selling the oil and gas. Although tasmanite mines are retired now, a company called Boss Resources, a mining company based out of Perth, is considering reopening it as the prices of oil and gas continue to rise. They would mine the tasmanite and then ship it to China, where it could be processed and the hydrocarbons could be utilized and sold, since China lacks abundant reserves of natural oil and gas.

In the afternoon as we approached Mole Creek, we stopped at the nearby cave system, the Marakoopa Caves. The caves are sacred to Aboriginal history: Marakoopa is an Aboriginal word for the word handsome. The cave system, a geological formation called karst terrain, is comprised of limestone and was formed about 450 million years ago when Tasmania was part of the supercontinent Gondwana and located close to the equator. The tropical seas were full of corals and small marine animals that gradually contributed to the formation of the limestone. Over time the rocks were gradually lifted up to sea level. Approximately 50 million years ago, as Australia was separating from Antarctica, a large river exposed the limestone in the area. Then 30 million years ago the drainage from this river was disrupted by basalt flows, forcing the channels to either side. These channels, now called the Mersey and Forth Rivers, began eroding the limestone, thus beginning the formation of the karst. Percolating groundwater gradually dissolved the calcium carbonate of the limestone. Slowly the small cavities dissolved becoming larger and larger and eventually connecting to one another. Over the last two million years, several glaciations have occurred that further eroded the limestone, depositing sand and gravel in the valley and even right into the caves through these underwater channels. Today water continues to pass through the caves and erode the limestone, further developing the Marakoopa system.

The group ended the day discussing possible project ideas with Professor Domack.  Students are thinking back to all of the field course stops and trying to pick a topic that is both interesting to them and possible to research. We cooked a big spaghetti dinner as we watched the pink sunset over the Western Tier Mountains in Mole Creek.

Professor Domack collects a sample of the Tasmanite from the abandoned mine. The exposed surfaces have weathered over time to the red-brown color.
Professor Domack collects a sample of the Tasmanite from the abandoned mine. The exposed surfaces have weathered over time to the red-brown color.
Stalagmites and stalactites form when water dissolves calcium carbonate from the limestone and evaporation or changes in temperature can cause the calcium carbonate to precipitate out of the water. Here, they have met and become one structure.
Stalagmites and stalactites form when water dissolves calcium carbonate from the limestone and evaporation or changes in temperature can cause the calcium carbonate to precipitate out of the water. Here, they have met and become one structure.
This helmet shell fossil is approximately 3ft long and is from the Gordon Limestone. It was on display at the entrance to the cave system.
This helmet shell fossil is approximately 3ft long and is from the Gordon Limestone. It was on display at the entrance to the cave system.

 

June 24, 2013
By Lindsay Pattison '16

On our second day in Wynyard we first drove to Rocky Cape, known to the aboriginals who occupied this land previously as Tangdimma. Here Gene gave a brief lecture on the rock type of this area, Precambrian quartzite, and how it differs from nearby Table Cape, which is composed of basalt, seen in the distance from Rocky Cape. We also discussed how the rocks at this site indicated more and less resistant bed sets in addition to cross bedding dipping S/SE at an angle of 30-60 degrees. By observing the cross bedding we were able to determine the axial zone of anticline (the line at which the dip in the cross bedding switches from a S/SE dip to a S/SW dip). At Rocky Cape we sketched the landscape and labeled the rock structures and then had a little time to scour the beach for interesting rocks and shells, before taking a short walk up to an aboriginal cave at Rocky Cape. The cave we visited was previously inhabited after ice ages and changes of sea level by the Rarerloihenna people, and in the cave we were able to see middens, remnants of the aboriginal people’s feasts on periwinkle (winna), abalone (makranya), and other sea creatures.

After our stop at Rocky Cape we drove to Table Cape, composed of iron containing basalt from the Eocene to Miocene. Gene gave a lecture at Table cape about the long rift valley that was created between Antarctica and Australia and Tasmania during the early Cretaceous period. The sediments that were dumped into the rift as it subsided contain some of the best dinosaur fossils. The rift process was later and more protracted than most of the separation and rifting that occurred with the rest of the continents composing Gondwana. However, instead of creating a rift basin, a fracture zone occurred between Tasmania and Antarctica resulting in a strike-slip motion rather than a divergence motion. The rift also resulted in a saddle where the area under the ocean closer to southern Australia and East Antarctica landmasses are older than the area directly along the midline (South East Indian Ridge) between the two, where there is a depression of younger ocean crust. When the Tasmanian fracture zone opened it formed a deep passage between Tasmania and Antarctica during the earliest Oligocene and Miocene. This opening resulted in a circular Antarctic current through the Tasman Ocean Gateway, allowing the Westerly Winds to encircle the world and causing thermal isolation of Antarctica, making it much colder than other parts of the world to the north of the Westerly Winds. The separation between Tasmania and Antarctica was the last pathway for transferring animals, which is indicated by the fossil record of marsupials in Antarctica.

Gene then discussed the Bass Strait, which was directly behind us as he explained the geology of the area we were sitting in. The Bass Strait is an alucogen, a failed shallow marine rift. The Bass Strait had higher sediment depths and was less well oxygenated, preserving organic matter better, and was therefore high in hydrocarbons used to make oil and gas, evidence of which was first discovered in the Bass Strait by Lewis G. Weeks.

After a quick ride in the vans, we arrived at Fossil Bluffs in Burnie. After a lunch break, we decided to take a geology break as well and one of the grad students who were driving us on our overland trip, Ben, taught us how to play Aussie Rules Football. We had an epic Aussie Rules game, which the ‘hats’ team won, although the other team put up a strong fight.

The tide was low enough after our game that we were able to walk along the beach and across some boulders to the a couple different sites along the Fossil Bluffs. Here we observed the nature of the contact between the gray horizontal bed unit, and the pale buff colored unit directly above, littered with fossils of gastropods and other sea creatures. We drew another sketch of the bluff and indicated differing stratigraphic layers. The lower interval was composed of recessive, finer grained siltstone and mudstone with isolated mudstones and Calcium Carbonate lenses. Above this layer, the sandy buff unit was a conglomerate, coarse grained, and had a diverse collection of fossils that became less diverse as one looked up higher on the bluff face. In between these two distinct areas was a sharp erosive contact, indicating that there was some missing link due to a low angular unconformity between the two layers of approximately 280 million years, between the Miocene and the late carboniferous. In this area, the ydensis the most primitive marsupial to be found, dating from the early Miocene, was discovered, and is a possible stem lineage for wombats or koalas. Because of the discovery of this fossil, combined with the other fossils in the rock at Fossil Bluff, the area was near shore marine before it emerged as the sea levels subsided.

At another part of the lower interval below the paler upper layer is diamictite, which we have seen and discussed at other stops along our overland trip. However, this diamictite bed is slightly tilted, and farther down the beach, the diamictite is actually going under the mudstone.

After studying the stratigraphy of the site, we roamed the beach and looked at the millions of fossilized gastropods and mollusks before getting back in the vans and heading home to Leiusureville in Wynyard for a delicious home cooked supper.

A group of students and Gene stand on Table Cape. Behind them is the Bass Strait, a failed rift with a plethora of organic matter. Table Cape is composed of basalt, which was deposited by a volcano in the nearby distance.
A group of students and Gene stand on Table Cape. Behind them is the Bass Strait, a failed rift with a plethora of organic matter. Table Cape is composed of basalt, which was deposited by a volcano in the nearby distance.
As a break from studying the geology of the surrounding areas, we play a game of Aussie Rules Football. The ‘hat’ team won by ten points, but the non-hat team came pretty close to winning until the last couple minutes.
As a break from studying the geology of the surrounding areas, we play a game of Aussie Rules Football. The ‘hat’ team won by ten points, but the non-hat team came pretty close to winning until the last couple minutes.
 Three students sketch the Rocky Cape landscape. The rock outcrop in the background displays dipping cross bedding. This area was home to the aboriginal Rarerloihenna people.
Three students sketch the Rocky Cape landscape. The rock outcrop in the background displays dipping cross bedding. This area was home to the aboriginal Rarerloihenna people.
Students observe the erosion and study the fossils at Fossil Bluff. The boulders here were once part of the pale buff upper unit of rock filled with fossils. Just above this beach is the grassy flat where we played Aussie Rules Football.
Students observe the erosion and study the fossils at Fossil Bluff. The boulders here were once part of the pale buff upper unit of rock filled with fossils. Just above this beach is the grassy flat where we played Aussie Rules Football.

 

Figure 1 - Famous iconic imagery of Cradle Mountain seen at a distance before students began their strenuous climb.
Figure 1 - Famous iconic imagery of Cradle Mountain seen at a distance before students began their strenuous climb.
Figure 2- Scenic view of Crater Lake in the foreground and Dove Lake in the background.
Figure 2- Scenic view of Crater Lake in the foreground and Dove Lake in the background.
Figure 3 - Students were able to observe these cute little guys all at close distances during the day and night.
Figure 3 - Students were able to observe these cute little guys all at close distances during the day and night.
Figure 4 - Madison Beres '15 and Nora Boylan '15 celebrate as they reach the summit of Cradle Mountain.
Figure 4 - Madison Beres '15 and Nora Boylan '15 celebrate as they reach the summit of Cradle Mountain.
Figure 5 - Gorgeous example of the angular unconformity seen on the Cradle Mountain hike. Notice the distinct variation in composition.
Figure 5 - Gorgeous example of the angular unconformity seen on the Cradle Mountain hike. Notice the distinct variation in composition.
June 22, 2013 - Cradle Mountain
By Nora Boylan '15

Today we had the outstanding opportunity to explore yet another World Heritage Site, the impressive Cradle Mountain. Cradle Mountain was named by the Van Diemen’s Land Company due to the large dip between the two peaks of the mountain which resembles a baby’s cradle (Figure 1). This towering mountain is surrounded by open moorland and heath, with scattered lakes and tarns throughout the region. Early in the morning our entire group packed up our bags and headed out to conquer the 15,000 meter ascent.

Over the course of this seven-hour hike, not only did we get to see crystal clear lakes (Figure 2), furry wombats (Figure 3), and breathtaking views, but we were also exposed to some world-class geology. The entire hike up the mountain exposed us to white quartzite of Precambrian age, the main rock that makes up this region. The peaks of Cradle Mountain are mainly composed of the same dolerite we have been seeing throughout our entire trip. Towards the summit of the mountain there are several talus falls with boulders reaching impressive sizes. We had to scour these boulders in order to reach the top of the mountain and see first hand the columnar jointing of the dolerite. Basically, this means that the dolerite has formed structures resembling “organ pipes” due to the cooling of the dolerite as it intruded into the country rock. These structures were similar to the ones we saw when we hiked Mount Wellington. Although it was quite the strenuous trek to get to the summit, we were all thrilled to experience this spectacular geology coupled with the magnificent view and perfect weather (Figure 4).

Another unique aspect of the Cradle Mountain stratigraphy is the huge unconformity that occurs between the Precambrian Quartzite of Cradle Mountain and the horizontal beds of the Parmeener Supergroup. The quartzite and schist that make up Cradle Mountain are broken with an angular unconformity from the St. Clair surface. This angular unconformity is composed of flat boulder and pebble conglomerates with some tillite (Figure 5).  This unconformity represents the glaciation over two separate eras, the Cenozoic and the Paleozoic. These separate events both had glacial movement from the northwest into this region of Tasmania. It is due to these separate glaciation periods that there is a large, and very visible, unconformity at Cradle Mountain. It is also important to keep in mind that there are no marine beds in these region and instead all of the formations are composed of  glacial outwash or breccia from these two separate glacial events.

Apart from the geology we also loved the wilderness we were surrounded by. Throughout our entire hike up the mountain there were numerous King Bill Pines, conifers we had been previously exposed to. We also saw swamp gums like those in the Styx Valley. We all made sure to take the time to stop and look around during our ascent so we could witness these once in a lifetime views

 

June 20, 2013
By Kevin Herrera '16

Today the group departed from the Giant’s Table Cottages to continue the overland trek across the state of Tasmania. We passed the namesake of the cottages, the Giant’s Table, on our way to Strahan. The Giant’s Table is a large dolerite mountain with a flat top, hence the word table in its name.

We continued our trip along the overland track, which is the only east-west viaduct that cuts across the World Heritage Area that covers 25% of Tasmania’s landmass. Apart from a few trails that lead off into the thick forests, this area has been largely unexplored. We passed the Derwent Bridge and eventually reached the Burns and King Williams Plains from which we saw Mt. King William and the other mountains in the King William Range. After adequate time for photos we continued our journey across the largely untamed wilderness.

The Frenchman’s Cap, a large knob of Cambrian quartzite in the Plain of the Mists, was our next stop. After eating most of us went down the trail to the Franklin River. This river is untouched by humans and is one of the many rivers that leads to the Gordon River, which in turn dumps into the Macquarie Harbor. The trail continues on to the peak of the Frenchman’s Cap, a 3-5 day return. This mountain is one of the last major peaks before the West Coast Range. According to the people walking the trail, on arriving at the peak, there is another trail that has a 3-5 week return, only for experienced hikers and mountaineers.

From our rest stop at the Burns and King William Plains. Mt. King William is in the distance. Photo by Eugene Domack
From our rest stop at the Burns and King William Plains. Mt. King William is in the distance. Photo by Eugene Domack
The sparsely vegetated slopes around Mt. Lyell and Queenstown. Due to the acid rain     produced by the mine’s noxious fumes, all the vegetation perished and left the mountain     bare. It is slowly regenerating but some parts will never fully recover.
The sparsely vegetated slopes around Mt. Lyell and Queenstown. Due to the acid rain produced by the mine’s noxious fumes, all the vegetation perished and left the mountain bare. It is slowly regenerating but some parts will never fully recover.

Our next stop was to the historic town of Queenstown. It is the largest town on the west coast of Tasmania and is known for its mining. The Mt. Lyell mine was the richest mine in precious metals in the Southern Hemisphere. Gold and other metals such as lead, tin and zinc were discovered in the area in the 1880’s which lead to the clear felling of trees on the surrounding hills to fuel smelters. Smelting produced pollution, which created acid rain. The soil has no buffering capacity to absorb the acid rain and that killed much of the vegetation in the area and the hills around the town. This created bare, colored rocks and an odd lunar landscape that we were able to see today. We saw patches of green on the hills that demonstrate that vegetation is starting to recuperate in the area. In the upper hills however, the vegetation may never return.

After our stop in Queenstown, we continued on our way to Strahan. Once there we arrived at the Strahan Bungalows where we put our belongings down and went to witness the sunset on Ocean Beach, a long expanse of sand along the western Tasmanian coast. This beach was formed not only by the waves but also the Westerly Winds. The Westerly Winds, also known as the Roaring Forties, are interrupted only by Patagonia and Tasmania. This means that after crossing Patagonia, these winds do not encounter any land mass. We then walked along the beach and observed the rocks and shells present. The rocks on the beach were rounded by the wave action and we observed different types of rocks such as conglomerate, sandstone, and granite. Seeing the sunset along the pink and blue sky was the perfect way to end our day.

 

June 19: Valley of the Giants, Styx River Valley at Maydena
By Catherine Smith '13 and Alexander Kerman '14

We set out today to examine the Styx River Valley in the area surrounding the small town of Maydena. We began low on the slopes of a forestry service logging road measuring a section of tillite in the Maydena section of the Parmeener Supergroup. Although the authors of our section labeled it a “tillite,” this is technically incorrect, as formation names are meant to be based on descriptive rather than genetic terms. Tillite therefore implies that the sediments forming the rock were deposited as an unsorted glacial till. We practiced analyzing sedimentary rocks and measuring sections. The rocks we looked at were dominantly diamictities with clasts ranging from pebbles to small boulders with a muddy matrix, although there were some areas that were conglomeratic. The dominant lithology of the clasts was quartzite due to its resistance to weathering, although there were clasts of phyllite, limestone, and some igneous rocks too. Many clasts bore glacial striations as well. Although the section is not dated (due to an absence of fossils), we know that this represents the late Permian or Early Carboniferous based on its position below the Woody Island Formation that we explored next.

After measuring the section, we drove into an area of the Woody Island mudstone that was well-exposed at a quarry used to make road fill. This formation had enough fossils to assign a rough absolute date, but the fossils and sediments were so reworked that better age constraints are still needed. This fossiliferous mudrock was dark gray to red-brown in color depending on the weathering of iron bearing minerals in the rock, especially pyritized organic matter. We found several well-preserved specimens, including a nice Glossopteris leaf, a brachiopod mold, and a large pyritized coprolite (possibly from the marine giant Mososaur!). We also found many “lone-stones,” much larger clasts in the muddy matrix, and some glendonite, diagenetic calcite crystals that form in very cold organic rich environments, throughout the formation. There were no primary sedimentary structures such as bedding or crossbedding, which reflects some sort of reworking such as bioturbation post-deposition. We also spent some time breaking apart and smelling the rock, as it was petroliferous, due to high trapped organic content, and fresh surfaces smelled quite strongly of gas. In fact the Woody Island Formation bears much in common with areas such as the Marcellus Shale (Devonian in age) in the United States and other mudrocks in Africa and South America that are potential sites for hydraulic fracturing. Because Tasmania has largely been able to meet its electricity needs from hydraulic energy, it has not yet explored this as a source for energy. These two units represent important periods in Earth history, especially in the environment of Gondwana. The tillite represents the Paleozoic glaciation of Gondwana, while the mudrocks represent a transgressive marine sequence. By studying the contact between the two units, we can begin to understand how the climate shifted into the warm Mesozoic.

After we returned to the cabins, we took some time to hike down the Styx River and walk along the Tolkien Track (named for eucalyptus trees which appear similar to the “Ents” of the Lord of the Rings series). These majestic eucalyptus trees towered above the surrounding canopy, some reaching up to 87 meters! Afterward we discussed the definition of true wilderness and the threats facing the old growth forests of Tasmania. Finally before bed, we discussed the Stable Plateau that we were going to drive through on June 20, including the crystalline rocks that are radically different than the Permeener Supergroup we saw in Hobart and Maydena.

The Styx River was named after the mythological Styx River and was believed to separate the world of the living from the world of the dead. Its blood-red color is caused by tannins released from decaying organic matter in the forest around the river.
The Styx River was named after the mythological Styx River and was believed to separate the world of the living from the world of the dead. Its blood-red color is caused by tannins released from decaying organic matter in the forest around the river.
The Woody Island Formation. This mudrock is well exposed in this area, which allows it to be used as a quarry for road fill.  Analogous mudrocks are present in other parts of Tasmania, South America, Africa and Antarctica.
The Woody Island Formation. This mudrock is well exposed in this area, which allows it to be used as a quarry for road fill. Analogous mudrocks are present in other parts of Tasmania, South America, Africa and Antarctica.
Gandalf’s Staff is an 84m tall eucalyptus tree located on the Tolkien Track in the Valley of the Giants. This walking track is named for the large eucalyptus trees that resemble the massive Ents in the Lord of the Rings series.
Gandalf’s Staff is an 84m tall eucalyptus tree located on the Tolkien Track in the Valley of the Giants. This walking track is named for the large eucalyptus trees that resemble the massive Ents in the Lord of the Rings series.

 

June 18, 2013
By Aubrey Coon '16, Adriana Fracchia '14 and Michael Weinzierl '15

On June 8, we got an early 8 a.m. start and began our journey to Mt. Field National Park and Fern Tree Mudstone in Maydeanna. We spent the first hour and a half of our trip on the Tall Tree Trail, which was a prime example of a temperate forest. The forest was home to Eucalyptus regnans, one of the tallest trees in the world, second only to the American redwoods. The tallest recorded Tasmanian regnans were 98 meters high. The forest was replete with loud bird calls, which belong to the largest parrots in the world, the yellow-tailed black cockatoos. The forest looked prehistoric with giant ferns, loud bird calls, rugged topography and mossy undergrowth. After our serene walk through the forest, we continued to see a beautiful outcrop of fern tree mudstone in the form of a trickling waterfall. The layers of the fern tree mudstone, deposited in the Permian, show evidence of alternating ice rift debris. The group then left the rainforest to check into the Giant Table Cabins, our homes for the next two days and also home to a resident platypus.

After lunch, we left the cabins to get back on the trail to Lake Dobson, which was a half-hour drive up the side of Mt. Field. Here, we saw a superb example of a subalpine fern environment. We were witness to thousand-year-old pencil pines, beautiful snow gums and towering pandanis on the Pandani Grove Walk. The geology of this peak was very similar to that in Figure 4.

After this tiring day, the group returned to the Cabins to recharge for the next day trip to Styx River Valley of the Giants.

Professor Domack and student Katy Smith pose by the Ferntree mudstone waterfall.
Professor Domack and student Katy Smith pose by the Ferntree mudstone waterfall.
A beautiful example of a local treefern.
A beautiful example of a local treefern.
Students posing in front of the Pandani near Lake Dobson.
Students posing in front of the Pandani near Lake Dobson.

 

June 17, 2013

By Aubrey Coon '16, Adriana Fracchia '14 and Michael Weinzierl '15

We began our adventures today at The Bonorong Wildlife Sanctuary in Brighton, Tasmania. Once we passed through the gate, the group was immediately greeted by friendly resident kangaroos. The kangaroos were encouraged by the food we had to feed them and we were given a tour of the myriad local wildlife and fauna of Tasmania, including the famous Tasmanian devil, wombats, peacocks, exotic birds and parrots, koalas, etc. The sanctuary acts as a rehabilitation center for injured or endangered animals, especially the devil, which is currently a species suffering from Devil Facial Tumor Disease. This epidemic is transferred through infected skin-to-skin contact and is rapidly deteriorating the local populations. After the tour, the group returned to the hostel to prepare for our overland trek starting the following day.

A group of kangaroos enjoying a drink at Bonorong Sanctuary
A group of kangaroos enjoying a drink at Bonorong Sanctuary
A Tasmanian devil at Bonorong Sanctuary
A Tasmanian devil at Bonorong Sanctuary

 

June 16, 2013
By Teddy Clements '14

Today, June 16, we started off the day hoping to visit Maria Island. Unfortunately, the choppy seas prevented the ferry from running. Instead, we explored the Tasman Peninsula. The locations that we visited exhibited sections of the Malbina and Ferntree formations, part of the larger Parmeener supergroup. At our first stop we made our way down to the Tessellated Pavement that framed the waterfront. These muddy sandstone rocks have linear fractures formed from salt crystallization and cracking following stress fields in the environment. This resulted in a checkered landscape, which we traversed, artfully dodging the crashing waves. Our next stop was Fossil Bay, where we observed the entire Malbina formation in a large exposed outcrop. From our vantage point we were able to see the cyclic patterns of the resistant and recessive layers. The difference in the resistivity of the layers reflects the different paleoclimates of the Permian period. We concluded the day by visiting the Tasman Arch, Remarkable Cave, Devils Cave, the Blowhole, and an 18th century coalmine to better appreciate the history and beauty of Tasmania.

 

June 15, 2013
By Teddy Clements '14

We arrived in Hobart on June 13, greeted by Becca Straw '14, a fellow Hamilton student studying abroad at the University of Tasmania, and our two drivers, Ben and Laura, who are graduate students at the University of Tasmania. After settling into Hobart, we were graciously treated to a party with the Antarctic Institute at the University where we were able to meet a variety of academics specializing in Antarctic science. These locals made us excited to explore the abundance of wilderness and world class geology that is Tasmania. We feel fortunate that more than 20percent of Tasmania is listed as a world heritage area.

On June 14, we visited the Hobart Botanical Gardens to familiarize ourselves with the native Tasmanian flora. Among the variety of species we observed in the garden, we identified Eucalyptus, several types of ferns, sub-antarctic lichens and mosses, and the Silver Banksia. Specifically, we focused on the three Tasmanian fern species – the slender tree fern (Cyathea cunninghamii), the man fern (Dicksonia anarctica), and the black tree fern (Cyathea medullaris). We also observed the Silver Banksia, which is widely distributed throughout Tasmania. It can occupy a diverse range of habitats and is easily recognized by its yellow cone shaped flowers. We observed these same plants on the flanks of Mt. Wellington the following day.

After a relatively relaxed day at the Botanical Gardens, we decided to challenge ourselves with a hike to the peak of Mt. Wellington. Along the trail we observed pencil pine (Athrotaxis selaginoides), which grows in the wet, cool climates on the exposed slopes we encountered. We also were able to see the different rock types reflecting the greater stratigraphy of the Tasmanian geology. More specifically, Mt. Wellington contains from the base to the top, the following units: the Permian Ferntree mudstone, the Triassic Ross sandstone, and the Jurassic Dolerite. The dolerite is unique to Tasmania, as it is not found on mainland Australia. In fact it has more in common with the Antarctic Ferrar dolerite.

As we gained elevation, we encountered the Tasmanian Dolerite, a mafic, iron-rich, intrusive rock, which intruded into the area through sills and dikes. As the dolerite cooled, it formed distinctive “organ-pipe” columnar joints that towered in the skyline above us. We learned that this structure was formed by vertical propagation of cooling contraction cracks down the dolerite. Along the traverse there was also a rubble field of large boulders formed by weathering, which is known as a talus slope. Soon we managed to reach the summit of the mountain despite the extreme weather. Gale force winds, freezing rain, and bitter temperatures made reaching the observation deck that much more rewarding. Unfortunately, clouds wrapped around the peak of the mountain and obstructed the famously spectacular view. As we ate lunch and rested at the peak, conditions on the mountain worsened drastically, thankfully, Professor Domack braced the freezing cold and hiked down to our vans below to shuttle us down. We returned to Hobart safely and appreciated viewing a classic example of Gondwandan stratigraphy.

Students explore the Tessellated Pavement. Pictured from left to right: Nora Boylan '15, Becca Straw '14, Caroline Gregory '14 and Xander Kerman '14
Students explore the Tessellated Pavement. Pictured from left to right: Nora Boylan '15, Becca Straw '14, Caroline Gregory '14 and Xander Kerman '14
The naturally occurring Tessellated Pavement marked our first stop on the Tasman Peninsula. Here, conjugate joint pattern fractures propagate as salt crystalizes and cracks the mudstone.
The naturally occurring Tessellated Pavement marked our first stop on the Tasman Peninsula. Here, conjugate joint pattern fractures propagate as salt crystalizes and cracks the mudstone.
The Organ Pipes of the Jurassic Dolerite loom above. This vertical jointing and horizontal fracturing are characteristic of the columnar jointing at Mt. Wellington.
The Organ Pipes of the Jurassic Dolerite loom above. This vertical jointing and horizontal fracturing are characteristic of the columnar jointing at Mt. Wellington.

 

June 14, 2013
By Madison Beres '15

One of the most beneficial aspects of this trip is that we have the opportunity to visit and study some of the most beautiful and sacred World Heritage Sites of the Southern Hemisphere. A World Heritage Site, as defined by the United Nations Educational, Scientific, and Cultural Organization (UNESCO), is a location of special cultural or physical significance. Basically, these places, often including forests, mountains, lakes, and deserts, are maintained by the World Heritage Committee due to their outstanding beauty or natural importance, with the hopes of securing an idea of cultural conservation within nature conservation. As mentioned in our previous entry, we had the opportunity to visit one of the most cherished World Heritage Sites, the Great Barrier Reef.

As the world’s most extensive coral reef ecosystem, the Great Barrier Reef is of extreme importance to conservationists and geoscientists. As we dove and snorkeled around Thetford Reef (Figure 1) we were able to see why the reef holds such significance and why efforts to protect this ecosystem are crucial. Over the past few decades the destruction to these delicate reef systems has accelerated due to processes such as ocean acidification, sea surface temperature rise, salinity, and sea level rise.

One example of this destruction that we were able to witness first hand is coral bleaching due to the loss of symbiotic bacteria called zooxanthellae. As the sea surface temperature rises the algae that lives within the coral and gives it its vibrant colors dies, causing the coral to bleach and loose its color. In other words, as global warming increases the coral struggles to survive.

As we dove around the canyons of Thetford Reef we saw several “coral graveyards”, or areas where dead coral had built up on the bottom of the ocean. When the coral dies it turns a duller color, detaches from its substrate, and falls to the bottom of the ocean. The coral that we were able to see the most devastation within was the Acropora coral (Figure 2), which is a stony, hard coral with blue colored finger-like branches. We saw several of these corals on the bottom of the ocean, broken off from the main coral build-ups and no longer displaying their vibrant color (Figure 3).

Since the Great Barrier Reef is a defined World Heritage Site it is a Federal Marine Park and is protected by legislation such as The Federal Environmental Protection and Biodiversity Conservation Act. Legislation such as this is very important because of the imminent threat of ocean acidification. Since the reef is composed of organisms that secrete calcium carbonate the acidity of the seawater has a large impact on the reactions that secrete the coral. Since the levels of carbon dioxide in the atmosphere are increasing daily due to greenhouse gas emissions, rainwater, and therefore seawater, are becoming more acidic. As the acidity of the ocean increases it is more difficult for organisms to obtain the carbonate ion necessary to secrete the calcium carbonate that creates the beautiful reef structures. If we continue our current pattern of greenhouse gas emissions our reefs will struggle to survive, most likely resulting in levels of high erosion and depleting reefs by 2070.

(Figure 1) Jamie McLean '15 and Madison Beres '15 enjoying an introductory dive through Thetford Reef.
(Figure 1) Jamie McLean '15 and Madison Beres '15 enjoying an introductory dive through Thetford Reef.
(Figure 2) An example of living Acropora anthocersis, one of the most threatened of the coral species.
(Figure 2) An example of living Acropora anthocersis, one of the most threatened of the coral species.
(Figure 3) Notice the loss of blue coloring in the Acropora anthocersis on the outside edges, while the coral on the inside is beginning to lose its color.
(Figure 3) Notice the loss of blue coloring in the Acropora anthocersis on the outside edges, while the coral on the inside is beginning to lose its color.
(Figure 4) An example of the vast and beautiful species diversity evident everywhere on the reef.
(Figure 4) An example of the vast and beautiful species diversity evident everywhere on the reef.

It was very interesting for us to see the Great Barrier Reef first hand because we were able to witness first hand how unique and ecologically important this ecosystem is. Throughout our time of the reef we had the lucky opportunity to experience some of the breathtaking beauty and wonderful species diversity the reef has to offer (Figure 4). We all gained a serious appreciation for this ecosystem due to our exposure to its beauty, but also to its current destruction. It was extremely helpful for us to learn about issues such as ocean acidification and sea surface temperature rise, and then see first hand how the consequences of current human patterns will have a devastating effect on important World Heritage Sites, such as the Great Barrier Reef.

As we arrive in Hobart we are all eager to see the Tasmanian Wilderness, which also contains a number of World Heritage Sites. After the Great Barrier Reef we understand why World Heritage Sites are so noteworthy and in need of our study and protection. We are looking forward to our exploration of the Botanical Gardens today and our ascent of Mount Wellington tomorrow, both of which are examples of the unique wilderness of Tasmania.

 

June 13, 2013
By Teddy Clements '14, Hannah Wagner '15 and Caroline Gregory '14

On June 7, Professor of Geosciences Eugene Domack and eighteen Hamilton College students gathered at New York City’s JFK Airport to embark on a three-week field course to Australia and Tasmania. Three flights and thirty hours later the group landed in Cairns, a city located on the coast of Northeast Australia.

After exploring the city for a day, the class gathered Monday evening for a formal lecture on the history and formation of the Great Barrier Reef as well as the tectonic setting of the Queensland Coast. The group discussed the environmental conditions necessary for reef development, as well as how the duration and intensity of glacial and interglacial cycles over the last 2.5 million years affected global sea level. Finally, they considered how global sea level affected local marine processes and the formation of the Great Barrier Reef approximately 600,000 years ago.

The following day the group left Cairns on 66-foot sailing vessel, The Rum Runner, for a two-day expedition to the Great Barrier Reef.  Once safely moored at the reef, the group snorkeled and dove at a collection of patch reefs located on the calm, landward side of the barrier reef structure.  Because these reefs are protected from the wave action of the open ocean, the marine life and sedimentary facies found here differed significantly from the aquatic life found near the reef front, which the group was able to map the following day. After an exhausting six dives, the Rum Runner headed back to Cairns, and the group prepared for the next leg of the journey to Tasmania. In Tasmania, the group will be joined by Becca Straw ’14 and two University of Tasmania graduate students for the remaining portion of the course, which was last taught in 2007.

Our boat, The Rum Runner, stands in port in Cairns, Australia. On a two day trip, this vessel took us to the Great Barrier Reef, where we had the opportunity to snorkel and scuba dive. We will produce sediment maps of the reefs that we visited.
Our boat, The Rum Runner, stands in port in Cairns, Australia. On a two day trip, this vessel took us to the Great Barrier Reef, where we had the opportunity to snorkel and scuba dive. We will produce sediment maps of the reefs that we visited.
This Giant Clam (Tridacna squamosa) can be found all over the reefs that we visited. Both snorklers and divers got the opportunity to see these huge, multicolored clams anchored on the reef.
This Giant Clam (Tridacna squamosa) can be found all over the reefs that we visited. Both snorklers and divers got the opportunity to see these huge, multicolored clams anchored on the reef.
A sea turtle (Chelonia mydas) is one of the most exciting organisms to see on the Great Barrier Reef.  This turtle is swimming on top of cross bedded sediment and surrounded by the coral reef fringe.
A sea turtle (Chelonia mydas) is one of the most exciting organisms to see on the Great Barrier Reef. This turtle is swimming on top of cross bedded sediment and surrounded by the coral reef fringe.
Cupola