New paper: “Chemical composition of carbonate hardground cements as reconstructive tools for Phanerozoic pore fluids”

My friend Paul Taylor and I are junior authors on a paper that has just appeared in the journal Geochemistry, Geophysics, Geosystems (“G-Cubed”) as an in press accepted manuscript. We’ll be the first to admit that it is a bit outside our comfort zone in geology, but our contributions, along with those of the other authors, are a good example of interdisciplinary team work. We were led by Dr. Andrea Erhardt at the University of Kentucky. This project took about four years from first draft to published article. Here is the abstract —

This study uses the chemical composition of early carbonate cement precipitates in carbonate hardgrounds to understand the geochemical signature of near-surface carbonate mineral precipitation. As carbonate hardgrounds lithify at or near the sediment-water interface, they acquire cements that may be minimally evolved from paleo-seawater. While hardgrounds can be subaerially exposed during sea-level regression, geochemical changes from interactions with meteoric water can leave a distinct geochemical signature. Using a suite of chemical measurements, we explore the potential of carbonate hardground cements as paleoenvironmental proxies. Trace metal and isotopic ratios, including rare earth elements, Mg/Ca, manganese and strontium concentrations, d18O, d13C, and 87Sr/86Sr, were analyzed in the carbonate cements from 17 Phanerozoic carbonate hardgrounds. Of these samples, only our sample from the modern oceans has measurements consistent with primary precipitation from seawater; all other samples precipitated from chemically evolved seawater or were influenced by meteoric water, even if only minimally changed. While the more recent Cenozoic samples had seawater 87Sr/86Sr, the Mesozoic samples, in contrast, did not preserve seawater 87Sr/86Sr, even though the Mg/Ca, d18O, and d13C values were consistent with precipitation from seawater. Finally, the Paleozoic samples preserved expected seawater 87Sr/86Sr, though REE and d18O suggest primary precipitation was from evolved seawater. Additionally, we place our results in the context of open vs. closed system precipitation using transects of the Mg/Ca ratios across individual cements. Overall, we stress that one proxy provides only a partial record of fluid composition, but multiple measurements allow a potential understanding of the seawater geochemical signal. [Sorry that I couldn’t figure out how to include superscripts and Greek letters!]

Fortunately this journal requires a Plain Language Summary —

All potential archives for reconstructing ancient seawater chemistry have complicating factors, be it biological modification or secondary alteration. This study investigates a promising alternative, carbonate hardground cements. As carbonate hardgrounds form relatively quickly and in equilibrium with seawater, if a sample has remained unaltered it should retain the primary seawater chemistry. We evaluate 17 samples from across the Phanerozoic, compiling trace element concentrations and isotopic ratios to determine if a sample has undergone significant diagenesis. Overall, no ancient sample satisfies all criteria, but the suite of measurements allows for an evaluation framework for future samples.

Hardgrounds are synsedimentarily-cemented seafloor. In other words, sediments that have essentially lithified into rock on the seafloor. The top image is of an echinoderm-encrusted Ordovician carbonate hardground from the Kanosh Formation of west-central Utah, which was included in this study. I’ve loved hardgrounds for decades now, learning much from my friend, the master of hardgrounds, Tim Palmer of the University of Wales, Aberystwyth. You can see in the first sentence of the discussion in this paper the primary role Paul Taylor and I played: “Our samples were selected based on evidence of early lithification at the sediment/water interface through the presence of marine boring and encrusting organisms.” That early lithification is with calcite cement generated from seawater in some form, thus the possibility that these hardgrounds are archiving ancient seawater composition. Seawater composition, of course, tells us much about marine paleoenvironments.

Figure 4 caption: “Mg/Ca ratios, strontium concentrations, and Mn/Sr ratios for samples showing examples of A) closed and B) open system precipitation behavior. Samples from potential closed system environments show an increase in Mg/Ca ratios along the growth axis, while samples from open systems show uniform Mg/Ca ratios. Strontium concentrations and Mn/Sr ratios can be indicators of diagenetic alteration, with thresholds of less than 300ppm for strontium and Mn/Sr ratios greater than 2 consistent with carbonate recrystallization under chemically evolved pore waters. The red lines indicate the trace of the LA-ICPMS.”

One aspect of this project I appreciate very much: The results are fuzzier than we expected. No single geochemical proxy shows a full record of the composition of the original cementing fluids. It is the combination of proxies that gives us the best clues, which is an incremental move towards better understanding of ancient seawater geochemistry. It is nice to see such data, observations and ideas published without a tight evidentiary ribbon around it all. Science in progress!


Erhardt, A.M., Alexandra V. Turchyn, A.V., Dickson, J.A.D., Sadekov, A.Y., Taylor, P.D., Wilson, M.A. and Schrag, D.P. 2020. Chemical composition of carbonate hardground cements as reconstructive tools for Phanerozoic pore fluids. Geochemistry, Geophysics, Geosystems (in press; accepted manuscript online;

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Posts from Antarctica: The Season in Numbers

Greetings from McMurdo once again! After many delays and a lot of worry about whether we’d have time to complete our science goals, we have returned with lots of great data and plans for future work. If the weather holds, I’ll leave for Christchurch tomorrow on my way back home. I’m hopeful that in the coming weeks I’ll be able to write a few more blog posts about the science we did, but for now I thought I’d give you a quick summary of the season in numbers.

The TARSAN field team at Cavity Camp

11: Number of members of our TARSAN field team

In the photo above, from left to right: Doug Fox (science writer), Christian Wild (post-doc with Erin at Oregon State), me, Erin Pettit (lead PI, Oregon State), Ted Scambos (University of Colorado Boulder), Martin Truffer (University of Alaska Fairbanks), Cece Mortenson (field guide), Atsu Muto (Temple University), Dale Pomraning (University of Alaska Fairbanks), Bruce Wallin (University of Colorado Boulder), and Blair Fyffe (field guide).

Erin super excited to be getting on an LC-130 bound for WAIS Divide

20: Number of days I waited for delayed planes

I waited 13 days in McMurdo beyond our scheduled departure date (and my team members arrived a week earlier, so they waited about 20 days) and 7 days at the field camp at WAIS Divide (some of our team members managed to slide right through without a long layover at WAIS Divide). My fingers are crossed that I won’t add additional days to that number while waiting to leave for Christchurch!

A beautiful night at Cavity Camp

3: Number of camp locations

The entire team started at Cavity Camp on the eastern ice shelf of Thwaites Glacier. After about 2.5 weeks there, six of us flew to the Dotson Ice Shelf, while the remaining members traversed a few kilometers to camp over a basal channel carved into the underside of the ice shelf.

Dale (background) and Martin (foreground) drilling at Cavity Camp

2: Number of holes drilled through the Thwaites Ice Shelf

Although we had originally hoped to drill on both Thwaites and Dotson, logistical challenges limited the drilling to Thwaites. Martin and Dale drilled holes through 300 meters of ice at Cavity Camp and 249 meters at Channel Camp. Ted and Bruce installed instruments in the ocean beneath and on a tower above the holes, which will continue to transmit data back to us.

Erin, Martin, Bruce, and Ted installing ocean instruments in the first borehole

1: Number of squids we saw on the borehole camera

I don’t have a picture to share, but there was indeed a squid that checked out the camera, shot ink at it, and swam away.

A really spectacular view of the Thwaites Glacier calving front

80: Number of minutes on the plane between Thwaites and Dotson

Our pilot, Troy, took us along the calving front of Thwaites Glacier and up the Crosson Ice Shelf, giving us some of the most spectacular views I’ve ever seen.

Atsu lowering explosives into a borehole for active seismic data collection

64: Number of active seismic data points Atsu and I collected

We measured seismic reflections at 37 sites on Thwaites and 27 on Dotson. Each site took about an hour and a half, give or take.

Me working on sewing up the cook tent during the storm

8: Approximate number of feet of ripped tent we had to sew back together during a storm

When the rain fly on our cook tent ripped during a storm, we spent about three hours working as a team to sew it back together in winds gusting to 40 knots.

Christian making a phase-sensitive radar measurement

63: Number of repeat phase-sensitive radar measurements Christian made

He measured 46 sites on Thwaites and 17 on Dotson. He had to visit each site twice and measure precisely in the same location to get an estimate of ice-thickness change.

Christian with a permanent phase-sensitive radar installation on Dotson (Mt. Murphy in the background)

4: Number of long-term phase-sensitive radar installations

We left two phase-sensitive radars on Thwaites and two on Dotson to send data back that will tell us a lot about ice flow and basal melt rates.

Erin setting off for the day, towing her radar setup

270: Approximate number of kilometers Erin walked while dragging the radar behind her.

The radar has to be moved slowly and steadily across the ice-shelf surface, so Erin got plenty of exercise this season. I pitched in and did 14 km one day, and I can tell you that dragging that radar system is no joke!

Cece during a long day on the snowmobile

9: Number of ways Christian can whistle

These are the kinds of things you think about during a long day on a snowmobile.

Digging out snow blocks to build wind walls

6,408,795: Approximate number of shovelfuls of snow we moved during the season

Okay, that number might not be very accurate. But polar fieldwork really is mostly just shoveling.



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Anatomy of a Record High

Like several towns and cities in the midwest and northeast USA, Wooster, OH broke its daily high temperature record for January 11 last Saturday. Below is a graph of some of the data (made a little prettier in powerpoint) from the weather station I run at my house.

The outdoor air temperature is the black curve, and the two vertical shaded regions show a period of rapid warming (red) midday Thursday and a period of rapid cooling (blue) on Sunday morning. I’m about to teach a unit about weather and climate to start this semester in ESCI 275, and this weekend was a great example of how an extratropical cyclone (a.k.a. a “winter storm”) can impact the temperature you feel outside.  There wasn’t much rain in this storm, but the winds and temperatures show the impact. Courtesy of the Weather Channel, here’s what the situation looked like Thursday:

See that big red “L” on the border of Nebraska and Iowa? That’s what’s responsible for the crazy swing in temperatures.  The red line extending east from it represents a warm front — south of that front, the air was much warmer than north of that front. The white contours are isobars (lines of constant pressure), and those show that behind that warm front, southerly winds were bringing warm air northward. The arrows on the graph at the top show the same thing. If you’d watched a flag flapping in the wind all morning Thursday, you’d watch it twist around from the turning — northerly wind then easterly wind then southerly wind by midday.  The temperature rose by more than 20°F over a few hours Thursday as that warm front passed over Ohio.

Anybody who looks at weather maps obsessively knows that behind most red warm fronts is a blue cold front; and a cold front was beginning to form with this Low (a.k.a. cyclone (a.k.a. storm)), extending from Nebraska to Texas…. it was just delayed. By noon Friday, the Low in Nebraska shot all the way up to Canada, moving around that big area of stalwart high pressure (the blue “H”) to its east. (That’s often called a “blocking high”, by the way.)  The cold front extending from the Low on this second map is not a pure cold front, either.  Notice the alternating red and blue from Michigan down to Oklahoma? That’s a sign that this front was actually “stationary” — it wasn’t moving. This stalling of the front led to a delay in the cooling down part of an extratropical cyclone, so places like Wooster and Pittsburgh continued to see southerly winds all day Friday and most of Saturday. This led to a few oddities: 1) The daily high on Thursday was at 11:59 PM. 2) The daily high on Friday was also 11:59 P. 3) The temperature on Saturday peaked at a whopping 67.6°F at 2:15 PM local time in Wooster. That’s like May weather in January.

The fun did not last forever, though. The stalled section of the cold front re-formed a secondary Low, and by late Saturday, the cold front was on the move over the USA again. This last map is from 10:15 PM Saturday night, less than two hours before that secondary Low passed almost directly over Wooster. Temperatures dropped almost 30°F overnight, and Sunday felt a little more like winter.

That 67.6°F wasn’t just warm, by the way; it was higher than any temperature ever recorded on a January 11at the OARDC station in Wooster from 1900 to 2019. This last graph shows the same temperature curve as before, but it also shows box plots for the daily high temperature 1900-2019 for each day January 9 through January 13. A normal highest temperature of the day is between about 22°F and 42°F for this four-day period. (The red boxes show the “interquartile range”, meaning that the coldest 30 years are below the red box, the middle 60 years are inside the red box, and the warmest 30 years are above the red box.) That 67.6°F would have been a record for any of these four days. (The “whisker” ends show the maximum and minimum.) Moreover, those box plots are showing the daily high, not the average temperature for the whole day… so the fact that even Sunday remained above the median daily high the entire day when it’s the cold day is a further sign of how impressive that warm snap was.

And again, this happened because a Low pressure system started moving east, got stuck, and reformed into two separate lows — first a Canadian Low, then a Michigan Low. While it stalled and reformed, southerly winds kept pumping warmth into Ohio, and that’s what set the record on Saturday — we had nearly 60 hours of consistent southerly winds.

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Posts from Antarctica: Logistics Update and Local History

Hello to you all from… still McMurdo. While we’re all frustrated to still be playing the waiting game, a ray of hope appeared last night – a plane flew from McMurdo to WAIS Divide, for the first time in over two weeks! Furthermore, three planes (a Basler and two Twin Otters, in case you’re interested in planes) are en route with cargo today from WAIS Divide, with destinations at Lower Thwaites Glacier (a staging site for gear headed to the science camps), Cavity Camp (our first destination) and Grounding Zone (the first camp for the MELT team). In fact, we just found out that the Basler successfully made the first landing at Cavity Camp, and has brought a whole bunch of our cargo – Ted and Erin literally both just did cartwheels in celebration.

Unfortunately, the delays, along with some aircraft maintenance issues, mean that we’re not going to achieve all of our original science goals, at least this season. But with the latest big gains, we should still be able to get a whole lot of good science done. It’s possible I could now be leaving for the deep field as early as Friday (fingers crossed!), so I wanted to make sure to slip in one more blog post for you all before I go.

Locations of historic huts on Ross Island, from

A few years ago I got into reading many of the great polar exploration stories of the early 1900s. If you’re interested in some great reading, start with Alfred Lansing’s “Endurance” about Ernest Shackleton’s failed attempt to cross Antarctica between 1914 and 1917. Another brilliant classic, this time a first-person account, is Apsley Cherry-Garrard’s “Worst Journey in the World” about Scott’s 1910-1913 Discovery Expedition to the South Pole. And if you want to come closer to understanding the true depths that a human being can suffer, Lennard Bickel’s “Mawson’s Will,” about an ill-fated expedition to map the Antarctic coastline south of Australia, will give you a new appreciation for what early polar explorers have endured.


A view of Hut Point from behind my dorm, with the Discovery Hut in the foreground and Vince’s Cross near the tip of the point behind the hut.

Since I have some knowledge of these epic exploration stories, and some personal experience with icy locales, one of the most exciting aspects of McMurdo for me is the nearby historical sites. Ross Island has played host to many historic expeditions, which left three huts that still stand along the shoreline. Scott’s Discovery Expedition built the first hut at Hut Point in 1902.The Nimrod Expedition, the first expedition Shackleton led to the Antarctica, left a hut at Cape Royds in 1908. And Scott’s 1910-1913 Terra Nova expedition left a hut at Cape Evans. Unfortunately, with the thin sea ice this year, we won’t get to visit the huts at Cape Royds or Cape Evans, but Hut Point is visible from my dorm building and is just a few minutes’ walk down the road. You can’t go in on your own, but we arranged a tour for our whole team last week.


The Discovery Hut with McMurdo in the background.

Captain Robert Falcon Scott’s Discovery Expedition (1901-1904) was primarily focused on mapping and carrying out scientific research. It included many men who played key roles in later expeditions, such as Ernest Shackleton, and made many important discoveries, including finding the Dry Valleys (the only ice-free valleys in Antarctica).

Crates piled inside the Discovery Hut.

They also learned a thing or two about huts. The hut they put up at Hut Point was a pre-fabricated hut that was actually designed for the Australian Outback. As Australia is known for heat, not cold, the hut was designed to be shady, cool, and well-ventilated. As you might imagine, that’s not ideal for Antarctica. The men found the hut to be cold and uncomfortable, and chose to mostly live and work aboard their ship (the Discovery). The hut was used primarily for storage, as well as for some cooking and science.


A box from Scott’s 1910 Antarctic Expedition.

Despite its drafty interior, it was still a valuable shelter and equipment cache for later expeditions. Shackleton’s Nimrod expedition used the hut briefly in 1909, on their way back from an attempt to reach the pole. Scott’s 1910-1913 Terra Nova expedition used the hut (which was farther south than their hut at Cape Evans, making it a good jumping-off point for south-going parties) fairly extensively. The last people to use the hut were the Ross Sea Party of Shackleton’s Imperial Transantarctic Expedition, who left in 1916. It then lay untouched (and full of snow and ice), until it was dug out in 1956, the year McMurdo was founded.

The kitchen area inside the Discovery Hut.

The hut remains well-preserved today. I walked over to see the hut on my own not long after I arrived. I was engrossed in reading the sign on the door (which just indicates rules for entry), and suddenly jumped when I realized I was standing right next to a dead, decaying seal dating from 1916. When we got to go inside the hut, we found a high-ceilinged, open interior that had been curtained off into a main storage/living area and a kitchen area. There’s also one separate room, which was used primarily for carrying out scientific experiments and analysis. Artifacts inside are very well-preserved (other than a slowly decaying pile of seal blubber), and have been arranged for better viewing. There are crates, bags, and shovels from the expeditions, old tin cans and tools, and even some pieces of the biscuit that was a staple of their diet (I wouldn’t try eating it now!). You can faintly see on the walls where many of the men wrote their names.

Tools and supplies inside the Discovery Hut.

Just up the hill from the hut, out on the end of the point, is a cross that was erected in 1902 in memory of a Discovery crewmember who drowned near that spot.


The cross the Discovery Expedition erected at the tip of Hut Point in memory of George Vince.

Although the Discovery Hut is perhaps the most interesting historical site in the immediate vicinity of McMurdo, Scott’s 1910-1913 Terra Nova Expedition is much more famous. After several expeditions had made attempts, Scott was determined that a British man would be the first to stand on the South Pole. They made extensive depot arrangements and used a variety of techniques to get there, including ponies, man-hauling, and some experimentation with the earliest motor sledges. Five men from Scott’s expedition reached the pole on January 17th, 1912, only to find that the Norwegian Roald Amundsen had beaten them by just five weeks (incidentally, Amundsen is arguably also the first to reach the North Pole, as earlier claims are disputed, and he led the first expedition through the northwest passage). Still more tragically, Scott’s team never made it back; one of the men died on the march, one walked into a storm to sacrifice himself as he knew he was dying and was holding back the team, and the final three, Scott included, died in a blizzard in their tent, just 11 miles from a major supply depot.

The cross the Terra Nova Expedition erected at the top of Ob Hill in memory of the five men who lost their lives on the way home from the South Pole.

Before heading home, the remaining members of Scott’s expedition erected a cross at the top of Observation Hill to honor the lost pole party. They inscribed it with the names of the lost and a line from Tennyson’s Ulysses: “To strive, to seek, to find, and not to yield.” The inscriptions have all but worn away by now (you can still see faint impressions if you look closely), but the cross still overlooks McMurdo.

Biscuit left by one of the expeditions at the Discovery Hut.

Having spent a little time in the middle of the Greenland Ice Sheet, and being about to head out to West Antarctica, I can’t imagine the bravery and outright craziness it must have taken for early explorers and researchers to achieve what they did. I’ll be sleeping in a fluffy synthetic sleeping bag on two insulating pads; they had reindeer fur sleeping bags that sometimes began to rot partway into the expedition. We have high-calorie, high-protein, and mostly good-tasting meals and snacks, including a whole lot of chocolate; they survived on biscuit, pemmican (basically powdered meat mixed with fat and sometimes other ingredients), and often their dead sled-dogs. We’ll be back to the comforts of home in just a couple months, and in the meantime have several forms of communication with McMurdo and with home; they went away for several years with hardly any communication at all during that time. We may be facing a harsh environment in the field, but it’s a heck of a lot easier to face than it was 100 years ago!

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A course in nonsense

For many years I’ve offered a First-Year Seminar at Wooster entitled, “Nonsense! (And Why It’s So Popular)”. Today we finished the latest version of the course. The semester went so well I want to celebrate. The class of first-year students above (with our excellent Teaching Assistant Malik holding the book on the left) was enthusiastic, knowledgeable and creative. They all participated in the discussions and have the record of 100% of written assignments turned in on time. And they did all this work in a class that started at 8:00 am! The Nonsense course website has all the academic details.

Here is our course description and rationale: “A deep streak of irrationality runs through humanity, especially in these days of “post-truth” and “fake news”. Belief that the Earth is flat has increased dramatically among American young people, and a curious conspiracy theory centered on the mysterious “Q-Anon” alleges dramatic secret battles between the “Deep State” and a satanic cabal for control of the US government. Horrific mass shootings are dismissed as “false flags” employing “crisis actors” for obscure political gains. Anti-vaccination groups have triggered new outbreaks of diseases we thought were nearly extinct, and quack medical “cures” are as popular as ever. Why is such nonsense so common when information has never been easier to access? What are the dangers to society when irrationality is common? Do we have logical tools to sort bad ideas from good? In this seminar we will examine conspiracy theories, crank science, revisionist history, and other topics from the edges of reason. We will use original literature, websites, and films to explore the lure of these ideas and their social origins. Our primary textbook will be The Skeptics’ Guide to the Universe: How to Know What’s Really Real in a World Increasingly Full of Fake. Our course objective is to improve our own critical thinking, writing and speaking … and, in the words of the late Carl Sagan, to light a candle in a demon-haunted world.”

This book by the Skeptics’ Guide to the Universe team was a superb resource throughout the semester. I highly recommend it to any readers.

Obviously there is plenty of nonsense these days to keep a class busy. Our academic goal was to develop critical thinking, writing and speaking skills by sharpening them against the waves of irrationality around us. We also found that learning the history of an idea was where to start understanding its attraction and tenacity. The students will tell you that our studies of the Flat Earth stream of nonsense were the most frustrating — and illuminating. Fake News was the most irritating was the most irritating, and Holocaust Denial the most upsetting. Of course, every week of this semester had plenty of news about conspiracy theories. Above is an image of the class on a typical day. Note the name placards for each student. We used these not just to learn names, but also to keep the seating arrangements fluid through the semester.

Each student wrote a research paper on a particular area of pseudoscience or conspiracy theory, and then gave a presentation to the class, as Blakely is doing above. Every assignment provided tools and skills for this capstone experience, including writing essays, constructing annotated bibliographies, and giving short oral reports. This class came through with the best research papers I’ve seen at this level.

Teaching this class was an academic dream because the students were so responsive and responsible. Malik was the ideal Teaching Assistant because of his incisive intellect (he’s a philosophy and psychology double major), communication skills, and passion for teaching. He was an excellent role model for these beginning students.

This was an exciting course to teach because of the new material and challenges ever week. We live in an age of unprecedented nonsense, but I like to think that small groups of rational citizens like these students are beginning to make a difference.


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Posts from Antarctica: The Ross Island Trail System

Another day, another cancelled flight – the advance team is now hoping to get out tomorrow, December 7th. Erin said she was once delayed 3.5 weeks in McMurdo due to weather; we’re crossing our fingers that our delay is much shorter than that!!

As long as we’re here, however, we’re doing our best to enjoy ourselves as well as to get some work done. One of the pleasant surprises for me when I got to McMurdo was finding out that there’s a trail system. You can find a map of the Ross Island Trail System here:

Some of the trails, like the Castle Rock and Cape Armitage Loops, are really meant for ski travel (and I believe the Cape Armitage Route is closed this year, as the sea ice has been very thin). I’ve done a little bit of cross-country skiing in the past, although not much, and have elected not to try to properly learn at the moment out of an abundance of caution, as it’s typically not a good idea to risk a major injury before heading out to the deep field. However, I have been able to enjoy several of the hiking trails, which stay mostly on bare ground and offer some pretty fantastic views of the scenery.

Ob Hill, viewed from the Hut Point Ridge Loop

One of the most popular trails is up to the top of Observation Hill, usually referred to as “Ob Hill,” which is a small volcanic dome that looms over McMurdo. It’s about 750 feet high, and a short trail leads right out of town to the summit. At the top of the hill is a cross that was set up to honor Captain Robert Falcon Scott and the other men who lost their lives returning from the South Pole in 1912 (my next post will cover some of the history around here in more detail). The views are fantastic. There’s also a loop trail that circumnavigates Ob Hill, going all the way out to the tip of Cape Armitage, which is the southernmost point on Ross Island.

Bruce and Christian on the Hut Point Ridge Loop

Another great loop is the Hut Point Ridge Loop. Hut Point is the location where Scott’s first expedition built a hut in 1902, which still stands today. Bruce, Christian and I hiked the Hut Point Ridge Loop one stunningly beautiful evening, and thoroughly enjoyed the views out across the sea ice. In the distance we could see open water; the sea ice is likely to be mostly broken up by the time we return to McMurdo in late January (that’s also when penguins tend to show up; I’m crossing my fingers that we get to see some!).

A mother and baby Weddell seal on the sea ice near Scott Base

This post is really just an excuse, however, to show you some great pictures of seals. One hike that you can only do with a guide is a mile-long path through the pressure ridges near Scott Base (the nearby New Zealand research station). Pressure ridges form where winds and/or ocean circulation push sea ice against itself or against the shoreline. The sea ice buckles under the pressure, thrusting broken fins of ice into the sky. In the process, cracks and holes in the ice form, and Weddell seals use these access points to get to the surface. Many of the nearby Weddell seals have babies, which are a bit over a month old. Hope you enjoy the pictures!

A sea-ice pressure ridge with a surface melt pond


A sleepy mother seal with a playful baby seal


An alert baby seal


A very content seal

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Wooster’s First Paleoecology Course

This semester we introduced a new course into the Earth Sciences curriculum: Paleoecology (ESCI 215). It is the first new course I’ve developed in many years. It is designed to introduce students to ecological concepts and principles using the fossil record and the history of life. And to introduce students to the history of life and the fossil record using ecology! Our material was also continually informed by evolutionary theory, so much so that we could probably call the course Evolutionary Paleoecology. Our Paleoecology course website has all the details, including the syllabus, assignments, and weekly readings. The first Wooster paleoecology students are shown above at the start of the semester. I was fortunate to have a small class (nine students) and a superb Teaching Assistant (Alexis — in blue, closest to the camera).

This was a difficult course to plan because the students had such diverse course backgrounds. Some have had my Invertebrate Paleontology course. Some are veterans of History of Life. Some had both of these courses; some had neither. Ideally I would teach Paleoecology requiring the above two courses as prerequisites, but there is no way we could actually do that in our curriculum and course scheduling. (And it would be a small number of students who would take the thread that far.) So the Paleoecology course had to be challenging for the most experienced students and comprehensible for the rest. I think it worked. I certainly learned many new teaching techniques in the process. The following are snapshots of the students and some of our course activities.

You can’t have a paleo course of any kind in Ohio without using the extraordinary fossils found in the Upper Ordovician of the Cincinnati region. We had an extensive lab exercise with brachiopods collected from outcrops in SE Indiana. Above Will and Hannah are sorting and identifying specimens. Again, the Ordovician Atlas was a critical aid and inspiration.

We also benefited from the wonderful lab spaces in Scovel Hall, especially on the second floor. Paleoecologists need plenty of room to spread out!

Above our TA Alexis is advising Justine and Srushti on their brachiopod analyses.

The Biology Department occupied much of our lab space for two years as their new building was being constructed. When they moved out they generously left us several cabinets, tables and chairs that are now the basis of our new Imaging Lab on the second floor. Half of the lab is shown above. The students are “picking” foraminiferans from Eocene sediments for a paleoenvironmental exercise.

A highlight on a cold November day was our field trip to Brown’s Lake Bog, led by Greg Wiles and Nick Wiesenberg. We wanted students to see this extraordinary ecosystem and learn how Quaternary climates and environments can be tracked through the accumulated sediments. (Photo by Justine)

Will is here using a soil probe to measure the thickness of the soft bog sediments. (Photo by Justine)

This is our host Greg Wiles. It is such a good image I just have to post it!

Nick Wiesenberg extracted a peaty sediment core for us as a demonstration. We later examined a similar core in the lab. (Photo by Justine)

Andy kept us informed about the local reptiles and amphibians. He caught a frog and the snake above, returning them to the grass below after we admired them.

The capstone assignment for the paleoecology students was a GSA-style presentation on a paleoecological topic of their choosing. They each had remarkably clear, interesting and informative talks, from which I learned a great deal. I intentionally gave few guidelines for these student teaching episodes to encourage diversity of form and independence. Each student mastered the challenge — and enjoyed describing fascinating paleoecological case studies of their choice. Ciaran is shown above presenting her work on a group of Permian therapsids.

The paleoecology class on our last day, with a ghostly Anomalocaris lurking above. Alexis the wonderful TA is on the left. This was an excellent group of students with curiosity, intellect, and patience for my many teaching experiments. I’m looking forward to the next version of this course!

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Posts from Antarctica: Life at McMurdo Station

The latest update is that our advance team is delayed another day, and weather at WAIS Divide is looking iffy for another few days. That makes it fairly likely that the rest of our team could be pushed into next week before flying out, although we haven’t yet totally given up hope of getting out this week. Delays are an expectation when going through WAIS Divide, and we have enough wiggle room built into our schedule that we’re not yet concerned about having enough time to get our science done. But for our own peace of mind, we would like to get out soon!

Pretty soon I’ll run out of interesting things to tell you about at McMurdo, but I’ve got at least a couple more posts in mind. Since we’re spending lots of time in McMurdo, I can tell you a little bit about what life is like here and get you oriented to our current location. McMurdo is sited on the southernmost reliably ice-free land area in the world that also can be reached by ship. It’s dry and windy enough here that the snow tends to sublimate away before enough can build up on top to start making ice, so the ground stays mostly clear, making it a great place to build a research station.

Looking down on McMurdo Station from nearby Observation Hill

The map below shows McMurdo’s location on the tip of Ross Island. The solid red line on the map is known as the “grounding line” – it’s where ice goes from sitting on land to floating. Everything to the left of the solid red line is ice sitting on the mainland of Antarctica. Everything to the right of the solid red line is floating ice (or ice on islands). There’s also a dotted red line that intersects with Ross Island. That’s the approximate line between the permanent ice shelf (which is ice that has flowed from the ice sheet out onto the ocean but is still attached to the ice sheet) and sea ice (which is ice that froze out of ocean water, so it was never a part of the ice sheet).

The location of McMurdo on Ross Island, with nearby features labeled. The satellite imagery is from the MODIS Mosaic of Antarctica (MOA) 2009 image.

When you stand on the shoreline at McMurdo this time of year, it’s hard to remember there’s an ocean there, because McMurdo Sound is full of sea ice (and also seals; spoiler alert, my next post will contain pictures of baby seals!). It’s also difficult to tell where the sea ice ends and the McMurdo Ice Shelf begins. Most lines between sea ice and an ice shelves are very obvious because ice shelves tend to be much thicker than sea ice, but the McMurdo Ice Shelf is very thin, making the dividing line difficult to spot. It’s possible to drive vehicles and even land planes safely on the sea ice this time of year, and it’s safe to do that year-round on the McMurdo and Ross Ice Shelves.

Looking out over the sea ice on McMurdo sound on a beautifully lit evening.

Most of McMurdo life, however, takes place on solid ground on Ross Island. McMurdo Station was founded in 1956 and is the largest research station in Antarctica. In the summer it houses around 1,000 people, and can support up to ~1,250. In the winter the population dwindles to just a couple hundred. McMurdo was built for functionality, not for aesthetic; it has a very industrial feel. Buildings are fairly austere, although a few are cheerily colored, and they’re all numbered (although there’s no spatial logic whatsoever to which number is where!).  None of the roads are paved and heavy machinery is abundant, so you spend a lot of time walking in wheel ruts. Being new to McMurdo, I made the mistake of brining tennis shoes rather than hiking boots for daily wear. Fortunately, there’s a building where any item left behind by someone in the past is available to anyone else for free, and I happened to walk in 10 minutes after a pair of brand new hiking boots in my size were set out on the shelf. I am at a loss as to why someone abandoned them, but I’m feeling very lucky that I was able to snag them!

A typical scene around McMurdo.

Everyone lives in dorms at McMurdo and eats in the dining hall, which is known as the Galley. Ingredients – particularly fresh ingredients – are often very limited, but McMurdo’s cooking is excellent (particularly when it comes to desserts). There is a store on-site, as well, where you can buy necessities like shampoo and medicines, comfort items like chocolate bars and alcohol, and a range of souvenirs (I confess that it seems strange to me that the McMurdo souvenirs aren’t available to purchase in Christchurch – as it is, they fly everything down so we can fly it back home. On the other hand, it does mean that my family members will get shirts that have actually been to Antarctica!).

The Galley, where an artist-in-residence was giving a talk on Scott’s Terra Nova Expedition.

As McMurdo’s primary function is to support scientific research, many of the buildings are dedicated to science or to getting scientific equipment out into the field. Our team spends most of the time during the day squeezed into a couple offices in the Crary Laboratory building, which also houses equipment for chemical and physical experiments, and includes a set of aquariums on the lower level with bizarre Antarctic aquatic organisms. We also spend a lot of time at the Science Support Center (SSC) where we did our rope training, which has space to set up tents and stage gear inside, the Berg Field Center (BFC) where much of our issued field gear is housed, and Science Cargo where we sort and package all of our equipment on pallets and turn it over to the professionals to get it loaded onto the plane. Our team has approximately 37,000 pounds (yes, that’s the correct number of zeros) of equipment to carry out our science and live fairly comfortably in the deep field for a couple months, and getting it all labeled, weighed, organized, and entered into the cargo system is a huge task.

Our team members putting away an Arctic Oven Tent that we had set up inside the SSC. Getting all the air out is a team effort.

Although we have been working hard, McMurdo also has many opportunities for leisure time. There are several gyms on-site, as well as a great set of hiking trails (which I’ll talk about in my next post!). We have lectures twice a week from scientists and artists-in-residence, either in the dining hall or in the library at Crary Lab. There are three bars (one of them is also a coffee house) that are very popular in the evenings, which often host scheduled or unscheduled parties. And there are several other rooms that provide diversions, such as the craft room and the gear distribution center, which includes skis and mountain bikes as well as musical instruments for loan. We even have several TV channels that get sports or news feeds from the US, and a local channel that plays movies.

The gym that houses the cardio equipment, known as the Gerbil Gym.

We’re really anxious to get out of McMurdo so we can start our research, but it is pretty incredible what kind of support systems are available here. Just across the bay from my dorm is a hut built by Scott’s Discovery expedition in the early 1900s (I will also talk more about that in a later post). I don’t think that any of those men, who huddled in the drafty hut through long Antarctic winters, could have guessed what incredible amounts of infrastructure would be built on Ross Island in just a few short decades.


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Posts from Antarctica: Staying Safe in the Field Part 3: Communications

We’re crossing our fingers that weather holds well enough at WAIS Divide to get a plane out there this evening, but our advance team is currently delayed until tomorrow (December 3rd). The earliest the rest of us will get out is still pencilled in for Thursday, December 5th, but we’re playing it by ear.

Once we do get out of McMurdo, to get to our field sites we fly to the permanent camp at WAIS Divide, possibly from WAIS Divide to a fueling stopover/gear cache at Lower Thwaites Glacier, and then to “Cavity Camp” on the floating portion of Thwaites Glacier. Cavity Camp is very remote, and our site at Dotson will be even a bit more remote. We are bringing everything with us that we need and then some, but to get all the gear there, and in case of an emergency, it’s extremely important that we have good communications among the team members and between the team and operations staff at WAIS Divide and at McMurdo.

Our team leader is Erin Pettit from Oregon State University. She is extremely experienced in field research, and, fortunately for us, is also fantastic at creating a functional and positive team environment. Everyone on the team has assigned responsibilities. Some of those responsibilities are scientific. For example, Atsu is in charge of managing the seismic surveys, Erin runs the ground-penetrating radar, and Martin and Dale are in charge of the drilling. My primary role is to assist Atsu with the seismic measurements, as his setup takes two people to run, and I also have responsibilities for strategizing data collection for a few features of interest and integrating our plans with the big-picture context of Thwaites Glacier and the Amundsen Sea. In addition to science duties, everyone will pitch in to help around the camp. Some people will be on cooking and cleaning duties, for example, while another will keep an eye on the tie-downs and guy lines used to hold gear and tents in place in case a storm whips up. Giving everyone clear responsibilities means that no important task slips through the cracks.

Our camp under Mount Erebus during our overnight shakedown

To work out these team responsibilities and facilitate trust and open communication, as well as to test out all our gear, we had an overnight camp “shakedown” as part of our training. We went out on the McMurdo Ice Shelf to an absolutely stunning location under Mount Erebus, the southernmost active volcano on Earth, which gently steamed under a crystal clear blue sky. Cece and Blair gave us some tips on setting up tents with strong snow anchors, cutting snow blocks, and building wind walls. Bruce and Christian decided to dig themselves a large trench with slots in the sides to sleep in, just for the fun of it (they did, in fact, sleep in their trench, but they failed to dig big enough slots to allow them to turn over, so they were stuck in one position all night). It was actually a really relaxing and enjoyable overnight. If we get that kind of weather in the deep field, it will be lovely trip; but it didn’t give us much experience testing our gear in harsh conditions, which we’re likely to face!

Bruce (left) and Christian (right) starting to dig their trench. They cut slots in the sides of the trench and slept in the slots on our shakedown.

While we were on our shakedown, we also tested out some of our communications equipment. Much of our communication with McMurdo will be via satellite transmissions. We have four satellite phones with us, as well as a satellite internet uplink that will let us send text emails back to McMurdo (and hopefully some blog posts back to the Wooster Geologists blog!). Eight of us on the team also own inReach devices, which are GPS units that also link to the Iridium satellite network, allowing us to text family from home and also to send text messages to each other in the field. For emergencies, we also have a high-frequency (HF) radio with a huge antenna that we can set up – we practiced using that on the shakedown, as well.

Team members setting up the HF radio

We will check in with McMurdo at a specific time every day. If we don’t check in by our specified time, McMurdo immediately initiates search-and-rescue operations, so we’re all responsible for remembering to make that check-in on-time. Since we will have multiple teams working away from camp to take radar and seismic measurements, we will also have set check-in times every few hours with each other. The daily check-ins with McMurdo will also include sharing weather observations and forecasts, which will be very important in planning our activities each day. Although every team that leaves camp carries survival bags, getting caught out in a storm is not something we intend to do!


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Posts from Antarctica: Staying Safe in the Field Part 2 – Safety and Crevasse Rescue Trainings

The United States Antarctic Program (USAP) primarily exists to support scientific research in Antarctica. In order to provide that support, one of their most important functions is to ensure the safety of all personnel involved in the research. Much of our time at McMurdo has been spent doing trainings to get us oriented to the station, our environment, and the equipment we’ll be using. I’ve had general trainings on operating NSF’s light vehicles, waste management, medical facilities, fire prevention and response, harassment, and environmental protection. I’ve also done field-oriented trainings on understanding the contents of our survival bags (we carry these with us at all times off station or out of camp; they include things like emergency tents and sleeping bags, a stove, fuel, and food), recognizing signs of hypothermia and frostbite, assessing and managing risk, and driving snowmobiles. We also do trainings that are specific to where we’re headed in the field. In our case, that includes crevasse rescue training.

Our team is headed (as soon as we can get out of McMurdo) for two camps in the deep field, both of which are on ice shelves. Ice shelves are the floating extensions of the ice sheet: they’re connected to and flowing with the ice on the continent, but they are also truly floating on the ocean, going up and down with the tides. Since the undersides of ice shelves are sitting in water, there is virtually no friction at their bases slowing them down, so ice tends to speed up when it flows into an ice shelf. Any time ice speeds up, goes around a bend, crosses a big change in elevation, or hits a bump in the bedrock, it tends to crack, forming crevasses. These crevasses can be hundreds of feet deep and are often hidden by a fragile layer of snow known as a “snow bridge,” which can be very difficult to spot. If you unknowingly cross a snow bridge, it may collapse under your weight, dropping you into the crevasse.

We plan to do our best to avoid crevasses in the first place. Our team includes two professional field guides, Cece and Blair, who will scout all our sites and travel routes before we use them for science. That has been done as much as possible already using high-resolution satellite imagery. Once our advance team gets to WAIS Divide, they will go out on one or two reconnaissance (“recce”) flights to inspect our sites from the air. If it’s safe, the pilot will land, and Cece, Blair, and our team member Martin will run radar to double-check that there aren’t bottom crevasses in our camp location that could disrupt the drilling operations. Once the team gets to the field, Cece and Blair will travel the routes we plan to take and use flags to mark areas that are safe and indicate hazards to avoid.

Proving routes in this way is incredibly valuable and raises our margin of safety greatly, but we will be in a rapidly changing environment, and new crevasses can open or be uncovered during our time in the field. We will ensure that our campsite is in a spot that is really, really safe, so there’s no problem walking around there without extra precautions. Anytime we move outside of camp, however, we will used roped travel, whether that’s on a snowmobile, on foot, or by ski. In this system, everyone wears climbing harnesses, and attaches their harnesses to knots in a long rope connecting the party. Each member of the team is spaced out a good ways – our foot/ski ropes will have a 15-meter spacing between people, and the snowmobile rope teams will have a longer spacing. The idea is that if someone breaks through a snow bridge, the other people on the team will be able to catch them on the rope. When we did our crevasse rescue training in the field last week, part of what we did was learn how to properly lay out ropes for travel, tie the right knots, and clip in securely.

Blair sets up knots in one of the ropes that we will use in the field for roped snowmobile travel

Once a person falls into a crevasse and is caught by the rope, there are lots of options for getting that person out. Assuming the person is conscious and can communicate, the team can start by just trying to walk away from the crevasse and haul them out. It’s really important to communicate, however, because sometimes crevasses have overhangs that the person can get crushed under as the team hauls them out. If the person can’t communicate (perhaps they’re just too far away to hear), or if the team isn’t strong enough or the footing not solid enough to haul the person out by walking, there are a bunch of options.

First, the person in the crevasse will be connected to the rope with two smaller looped cords, attached with a knot called a Prusik hitch. This hitch can slide up the rope easily when not under tension, but holds tight when weighted. One of those Prusiks is attached to the waist of the harness, and the other is attached beneath it and has another loop tied in it that goes around the foot. If the person in the crevasse is able, they will stand up on the foot Prusik and move the waist Prusik up the rope. Then they put their weight on the waist Prusik and move the foot Prusik up, continuing that way until they can wriggle up over the edge of the crevasse.

Me practicing using Prusik hitches to move up and down a rope during our indoor rope training, while field guide Blair watches and gives me instructions

If the person in the crevasse is unconscious or unable to move up the rope on their own, the team up above needs to set up a pulley system to get them to the top. The first thing that has to be done is to make it so the team isn’t having to use their weight to keep the person in the crevasse from falling. This involves digging a snow anchor, in which some sort of stable object, such as a shovel, ice axe, or a piece of metal that has been designed to be a strong snow anchor, is buried a foot or two deep in the snow and rigged so it can be attached to the climbing rope that the person in the crevasse is on. Once the snow anchor has the person’s weight, the rest of the rope team have more freedom to move around to build a pulley system, get another team member down into the crevasse to help the person if necessary, lower another rope to the person in the crevasse, etc. Exactly which technique is used depends strongly on the individual situation. Fortunately, either Cece or Blair will be with every team working outside of camp, so they will be there to make technical decisions and give directions if a crevasse rescue is necessary.

Blair (right) helps Atsu and Doug rig a pulley system that can be used to get a teammate out of a crevasse

These techniques were all brand new to me. We practiced much of the rope work indoors first (I arrived in McMurdo at 3:30 in the morning and indoor rope training started that day at 8 am. I was a bit late, but I did make it!). The day after our indoor training, we spent the whole day out on the ice shelf where a bulldozer had been used to dig a large simulated crevasse. It was really valuable to practice the same skills we learned indoors in an outdoor setting – everything gets harder when you’re wearing gloves and your rope is digging into the snow.

Cece (top) helps Ted with some advanced crevasse rescue techniques in the bulldozed “crevasse”

We don’t expect to need any of our crevasse rescue skills; we intend to avoid crevasses in the first place. But we also need to be prepared in case we need to act in an emergency situation!

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