Wind, water, plants, heat, and gravity are constantly pounding, splitting, cracking, and pulling rocks. Little by little, they break down the rock into smaller pieces called “sediments.” They are transported away to varying distances and deposited in calm environments. Sediments pile on top of each other — layer after layer — as time progresses. Eventually, the pressure from subsequent layers is sufficiently strong to turn lower sediment layers into rock. The type of sediments, nature in which they were deposited, and chemical signatures that they record can provide information about the Earth’s climate at the time of deposition.
Sediments are the primary source of climate data for the years before 1960. Most famously, ice cores provide the best climatic records. Snowflakes fall onto glaciers. Their irregular shapes create gaps between individual flakes, thus trapping a small chamber of air from when they fell. Climatologists drill ice cores and analyze these air pockets to determine the state of Earth’s climate in the past.
But the oldest ice cores go back only 5 million years. The Earth is 4.5 billion years old. Deep sea cores of ocean sediments reach 130 million years before present. Tectonic activity destroys oceanic plates via subduction that are older. To see even further back in the Earth’s climate history, geologists study rocks made of the chemical compound carbonate (CO3).
Repetitive sequences of carbonate rock layers are scattered throughout the rock record. Geologist have interpreted these layers to represent fluctuations in sea level. But few study how carbonate rocks are forming in the present to understand if these layers actually record sea level change.
These issues form the basis of my sedimentology class. For spring break, we traveled to western Australia to study the preservation of sea level in sedimentary rocks.
Day 1-2— I left my dorm at 4:30 AM. The campus was dead quiet. My class lined up on Ivy Lane to take a bus to John F. Kennedy International Airport. We flew for 12 hours on an Emirates flight to Dubai, United Arab Emirates. Emirates is renowned for satisfying customers, and it didn’t disappoint. It provided good food, frequent refills on drinks, cushy seats with slightly more room, a high-tech entertainment system, and a packet with socks and a sleeping mask. There’s no way that any of the American airlines can compare with their amenities. None of the crew were American, and all of the flight attendants were women.
As we were descending into Dubai, I saw the Burj Khalifa — the tallest building in the world — rise out of the brown desert haze. It was a shiny needle shooting 2,700 feet into the sky, four times taller than the other buildings around it. Several manmade islands dotted the city’s coast.
We rushed to our next flight because our first one had landed late. The airport was more of a shopping mall than an airport. Stores from the finest European brands lined the walls next to globalized American chainstores. The vaulted ceiling was three stories high. Upper levels had lounges and crew quarters. Fifty-foot tall windows arced to a central ridge, providing a full view of the city skyline. There were people from across the Afro-Eurasian landmass: Europeans, Indians, Chinese, Arabs, and east Africans.
Our second flight lasted ten hours as it traversed the Indian Ocean toward Perth, Australia. The flight line from New York City to Perth is one of the longest in the world because the Australian city is near New York’s antipodes — the point on the opposite side of the Earth from another point. We arrived in Australia after midnight and stayed in a hotel north of Perth. Our room had a magnificent view of an Ikea warehouse across the street.
Day 3— We left the hotel and ate breakfast at a nearby café. Australians drive on the left side of the road, so our driver — a woman who was recently admitted to Princeton’s graduate school — had to adjust herself to the new rules of the road. Then, our nine-hour drive northward to Shark Bay began. Wide open Mediterranean scrubland soon turned into barren red desert. Dead kangaroos laid at the roadside every ten miles or less. Eventually, we drove parallel to the Indian Ocean. Its azure waves lapped up to the sparkling sandy shores. Towering white sand dunes were one half mile inland, slowly marching to the sea under the wind.
We stopped to shop for food in Geraldton, a town that is halfway between Perth and Shark Bay. It was small and industrial. There was a Hungry Jack’s next to a Target. “Hungry Jack’s” is the official name of Burger King in Australia. When the hamburger chain moved to the continent in the 1970s, another store had already trademarked the name “Burger King,” so the Australian franchisee chose another name. Hungry Jack’s is the second largest Burger King franchise in the world.
We arrived at Shark Bay around 8:00 PM. Our campsite was located on a beach within the Carbla homestead. Shark Bay is a national park, but several families were grandfathered into conditions that permit them to hold land on centurylong leases.
The Milky Way glowed above us as we set up our tents. The wind was warm and the waves gentle.
Day 4— I awoke by accident at 3:30 AM and saw a fantastic spectacle. Summer constellations had risen above the horizon. The brilliant white galactic core in Sagittarius was approaching the zenith. All was quiet. Not even the wind blew. The yellow eyes of quarter-sized spiders glittered on the hillside under my headlamp. I took some pictures and went back to bed.
Once the sun rose, the air warmed quickly. The ocean turned from plain blue to a sparkling turquoise. Small black flies swarmed around my head. They didn’t bite, but they were very annoying.
Our professor gave us a tour of the landscape. We first descended down several terraces of 1-2 meters in height that marked past shorelines when the sea level was higher. We then waded into the water to make additional observations. The water felt frigid. But, in reality, we were just really hot from being in the sun, and the water was cooling us down significantly. Our professor then showed us the stromatolites.
Stromatolites are one of the oldest forms of life. The earliest stromatolite fossils, found in Greenland, date back to 3.7 billion years ago. They form when a certain kind of cyanobacteria — bacteria that photosynthesize — form clumps and start retaining mud layers. Stromatolites dominated reefs for the first 3.5 billion years of Earth’s history but have been declining for the past 1 billion years. They were succeeded by sponges, rudists, and corals. Their fall was fueled by the rise of animals, which like to eat them. Today, they are limited to very saline water in environments that are too harsh for most animals. These locations include: Shark Bay, several other beaches and lakes in western Australia, Exuma Cays in the Bahamas, Lago Salgada in Brazil, Cuatro Ciénegas and Lake Alchichica in Mexico, and Pampa del Tamarugal National Reserve in Chile.
Stromatolites come in all shapes and sizes — called “morphologies” — but geologists don’t know what they signify. Hamelin Pool in Shark Bay has the largest remaining colony of stromatolites in the world, so our research projects would focus on understanding how their morphologies changed with water depth.
After walking in the water for some time, we headed inland to examine sand dunes. The temperature soared above 40ºC, and the flies intensified. Sand dunes’ shapes provide information about the environment in which they formed. Crescentic barchan dunes form when there’s little surrounding sand and one predominant wind direction. Transverse dunes occur in vast sand seas, and their crests are perpendicular to the wind. Longitude dunes are created by multiple wind directions. The dunes on the shore were parabolic dunes: barchan dunes that reversed as plants secured their edges and their central arches buckled under the wind. They indicate that the climate is temperate with sufficient precipitation to support vegetation.
We stopped to study the cross-bedding in the sandstone of fossilized sand dunes. Sand grains are pushed up the front side of a sand dune by the wind. After they cross its crest, the grains fall down the backside and are deposited in layers. As the wind pushes the dune back, successive layers are deposited on top of one another. Eventually, the land subsides, and these layers are preserved as cross-bedding in sandstone. By measuring the cross-bedding’s direction of inclination, we can determine the types of dunes that existed in the past and the general climate at the time of formation. The two cross-bedded rocks in front of us indicated that there was once a westward-oriented parabolic dune. This information tells us that the climate had enough rain to support plants and that the wind came from a seaward direction.
While the Sun was approaching high noon, the flies were getting worse. There was a never-ending buzz in my ears. They covered all of one student’s lips. For another, they were crawling on his neck. Three kangaroos rested under the shade of some rock bluffs no more than 100 meters from camp. We returned for lunch. The cheese in my box had melted onto my sandwich. Liquified peanut butter oozed out from between two slices of bread. Our water tasted like warm tea from being in the sunlight. In the morning, the land breeze had picked up and knocked over some tents. Now, it was calm.
For the rest of the day, I waded in the water with one of the stromatolite research teams. We walked along transects — straight lines that a person walks and periodically stops to take measurements or collect samples — that were perpendicular to the shore. The waves grew larger as the tide rolled in. It was new Moon, so we were experiencing the strongest spring tide of the synodic month.
Evening came as a relief. There were no flies after sunset. The air cooled to a comfortable 22ºC with a sea breeze. We ate dinner while watching the stars.
Day 5— The sunlight woke me up around 6:00 AM. Flies buzzed by my head as soon as I left my tent. I began the day by walking several transects parallel to the shore with an advanced GPS to record accurate elevation measurements.
By mid-morning, the stromatolite research team had decided to switch the focus of their project. I was paired with the student who I worked for in the Bahamas, and we went into a section of shallow water near camp to survey stromatolites.
The water was perfectly clear. Small fish darted away from us as we walked around. Their dark scales juxtaposed the white sand beneath them. The Sun’s rays scorched us with increasing intensity as its yellow disk rose higher into the sky. Reflections from the water were just as harmful.
I had learned my lesson after receiving terrible sunburn in the Bahamas. This time, I was much more prepared by wearing long sleeves, pants, gloves, sunglasses, a buff and hat. No one else was so fortunate. By the end of the day, they looked like tomatoes.
For the evening, I digitized the data that we had collected. For a few minutes, we stopped to watch the Sun sink below the horizon. The orange crescentic Moon followed it an hour later.
Day 6— I repeated the previous day’s activities. Our survey area shifted southward. After lunch, a sea snake — longer than an arm span in length — slithered out from behind a stromatolite. There’s a saying that goes, “everything in Australia is trying to kill you.” Sea snakes are no different. All sea snakes are deadly, but the worst ones can kill eight adult humans with three drops of venom. The snake that we saw was not as dangerous.
Shark Bay is also home to stonefish. They have spines on their back that inject venom into feet when stepped upon. If not treated immediately, the venom will kill a person. As the most venomous fish in the world, their sting has been described as one of the worst pains that a human can feel. We never saw any. But neither have the people who stepped on them.
We abandoned the stromatolite survey and collected grain samples along the beach for two kilometers during the final hours of the afternoon. The Sun was low by the time we returned to camp. Everyone ate dinner under the stars again.
Day 7— A sheen of cirrus clouds blanketed the morning sky. They reduced the day’s heat by a noticeable degree. My partner and I continued surveying stromatolites in a quadrangle one kilometer from camp. Since it was the final day of field work at Shark Bay, we rushed to collect as much data as possible. In the evening, I helped several students build a fire for roasting sweet potatoes. The clouds cleared to reveal the stars. ‘
Day 8— Thick clouds blocked the Sun. We packed up camp and drove out over Carbla’s wide red plains. There wasn’t much new for the first few hours of our southward drive. Green shrubs grew on desert pavement. Slowly, the scenery transformed into rolling hills and mesas below a pale blue sky. We continued to pass dead kangaroos. The class stopped for lunch at a Subway in Geraldton. After seeing several construction workers come in for lunch, one English classmate said, “Every Australian that I have seen has looked like a stereotype of an Australian.”
We arrived in Jurien Bay by mid-afternoon. Half of the class went to our rental bungalow, and the other half went to scout our next work site.
Situated only two hours north of Perth, Numbung National Park is the crown jewel of western Australia. Tourists flock to it during the cooler winter months. Thousands of limestone pinnacles rise up to five meters above the sand sea surrounding them. They come in a variety of shapes and sizes. Some look like tree trunks. Others are tombstones. Obtuse caps make pinnacles resemble mushrooms. A few are similar to candlesticks. Despite being one of western Australia’s icons, relatively little is known about the pinnacles’ origin. The signs in the visitor’s center say that they formed from a petrified forest or the remnants of plant roots.
But don’t let the signs fool you. Basic qualitative observations negate these hypotheses. The pinnacles contain several stratigraphic units — rock layers. In certain areas, the pinnacles have cross-bedding, and in another they feature paleosols, preserved ancient soils. Australian researchers conducted series of surveys in 2014-2017 and claimed that the pinnacles formed as the remnants of solution pipes. They are created when water dissolves holes in limestone. The researchers also said that the pinnacles contained climate data from Late Quaternary times.
Our car passed an emu as we drove into Nambung National Park. Dull yellow sand dunes greeted us at the entrance to the park’s road. We went to the central observation deck, and then walked around for an hour. The sheer number of pinnacles was remarkable. They littered the desert for at least three kilometers in one direction. At the top of a dune, I could see portion of the desert that contained only white sand. To the west, the Indian Ocean sparkled in the late afternoon sunlight. In the opposite direction, the red Australian outback stretched to the horizon.
We drove back to our house around 4:00 PM. My team spent much of the evening planning our research project for the next two days. After Shark Bay’s heat, it was nice to be in air conditioning.
Day 9— Following a quick breakfast, we set out for the Pinnacles Desert. Eight emus walked through the shrubs within ten feet of our car as we drove in. Our research permits gave us carte blanche to do almost whatever we wanted in the park. My group started the day by teaching the other students how to analyze individual pinnacles.
Then, we split up into teams. I worked with a Chinese graduate student on one central section. Our goal was to determine how the height of a paleosol layer in the pinnacles varied. One by one, I measured pinnacle after pinnacle for the entire day. Two tourists from Germany talked to us for a few minutes. Cars drove past us the entire day. In the late afternoon, thunder rumbled over the desert. Luckily, it didn’t rain. We left the park 30 minutes before sunset.
Day 10— We returned to the pinnacles for a final time. Blue clouds covered the sky. I worked with my partner on measuring the cross-bedding inclinations and their directions, called the “dip” and “dip direction” by geologists. At lunch, another graduate student drove us to the visitors’ center. We read about the park’s history, scoffed at the incorrect geology signs, and got ice cream. Then, we returned to work. The flies were as bad as ever. In the distance, the Indian Ocean turned dark blue. The class rendezvoused at the observation deck at the day’s end. A kangaroo hopped through the pinnacles.
Day 11— We left the rental house after breakfast. The hours blended together as we drove southward. Desert pavement turned back into green farmland. It became rainy when Perth’s skyscrapers came into view. Our drive ended at the far southern end of Australia’s western coast.
For the final day, we stayed in a beach house near Quindalup along Geographe Bay. It was a very nice house, and Princeton paid for it. The interior was airy. There were walk-in closets, glass bathrooms, king-sized beds, granite countertops, and a large television.
The class played frisbee and football on the nearby beach. I couldn’t believe that classes were starting at Princeton — which was 12 time zones behind us — while we were still playing around on the opposite side of the planet at the edge of the Australian continent. The vast expanse of the Indian Ocean stretched toward the horizon.
Our professor cooked a wonderful vegan dinner of mock shepard’s pie, salad, and chocolate covered fruits.
Day 12— Around mid-morning, we left the house and went to Ngilgi Cave. It had been used for shelter by local wildlife and the indigenous people for centuries. Aborigines thought that Ngilgi was a spirit for good who fought against the evil spirit Wolgine. In 1899, a local settler, named Edward Dawson, found the cave while looking for stray horses. He opened it for tours and was its tour guide during 1900-1937. It used to take an overnight train ride and two days of wagon travel to reach the cave. Visitors would follow the trail of empty beer bottles to get there. “That’s the Australian way of navigation,” said one of the cave’s current employees. In 1965, a woman from Perth stayed in the cave for 90 days to break the world record for cave sitting. During her stay, she excavated the skeleton of a 2.28 meter-tall megafauna kangaroo from earlier in the Pleistocene. Today, the cave remains a popular tourist attraction. Occasionally, there are concerts in one of its chambers.
We walked into the cave and looked at its dizzying array of stalactites, stalagmites, fins, and crystals. A thick red paleosol was visible in the walls of some sections. Ngilgi was the most impressive cave that I’ve seen yet. For lunch, we stopped at a bakery in the nearby Cave House.
Next, we went to the Petra Olive Oil Estate. Olive trees were lined in neat rows. A house was in the center of the property, and a pond was located 100 meters away from it. Kangaroos and wallabies lounged under the trees. The weather was mild thanks to a gentle breeze. It was paradise.
The owners temporarily opened their shop to us. They showed us how they made olive oil and let us sample some as it was falling straight out of the machine. Its smooth texture had a strong pang at the back of the throat after swallowing.
For the remainder of the day, we drove back to Perth. Around 10:00 PM, we boarded our Emirates flight to Dubai. I had vegemite during the in-flight breakfast. It was disgusting.
Day 13— Our airplane landed in Dubai at 4:30 AM. The airport was bustling in spite of the early hour. The class got smoothies and then dispersed. I walked around the airport for a few hours. My initial assessment of the place was still correct. I didn’t hear anyone with an American accent the entire time. Everyone appeared to be from the eastern hemisphere or western Europe. Most of the menial workers were Indian. Businessmen in suits were European and Chinese. The Burj Khalifa loomed in the distance behind a thick haze. If the UAE plays its cards correctly, Dubai will become the hub of the world.
I boarded our final flight around 8:00 AM. The airplane flew straight northward over the Caucasus Mountains, turned westward to cross Scandinavia, passed Greenland, and finally went south to New York City. Getting through customs was easy, and a bus brought us back to Princeton. I went to 30 Burgers for dinner.
Australia is a vast continent of untamed desert wilderness. For those who are unprepared, its relentless heat, intense dryness, and rocky terrain can be unforgiving. Although our trip covered two thirds of the distance along its western coast, there was much more that we didn’t see. Australia contains some of the oldest rocks in the world. But it also has some of the newest, most interesting geological developments.
As human-driven climate change advances, additional information about the Earth’s climate and its processes will be needed to understand its effects. Advancements in sedimentology will continue to provide new insights about how climate change occurred in the past. To study the natural processes that record these shifts and cycles, geologists will keep exploring the Land Down Under.