A Short Update from the Diabase Quarries

We have an early morning tomorrow, since we’re running our NE-SE GSA field trip for the Pennsylvania Geological Survey. So, this post will be short and sweet. Here are a few of the highlights from today’s diabase escapades:

One of Betty Lou's cores that we cut for geochemistry and thin sections.

More awesome slickenfibers.

Contact between diabase and a felsic layer.

Quarry workers drilling holes to set up for the next blast.

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Wooster Geologists in Alabama!

Mark Wilson (Wooster), Caroline Sogot (University of Cambridge), Megan Innis (Wooster) and Paul Taylor (Natural History Museum, London) on our first evening in Alabama. This is our "before" photograph. Let's see what we look like in 10 days of mud, sun and mosquitoes.

GREENVILLE, ALABAMA–We were told many times before this trip that we will find the people in the Deep South to be friendly.  This has been very much the case from the employees at the Atlanta airport to the young man in Greenville who insisted on carrying our few small bags of groceries out to the car.  We also knew it would be hot, muggy, and that at the store we could buy (if we ever wanted to) loads of pig’s ears and feet!  It is a delight to experience such cultural gradients in our own country.

Megan Innis, a senior geology major at The College of Wooster, is here with me to pursue her Independent Study project on changes in bioerosion patterns across the boundary between the Mesozoic and Cenozoic Eras (the “K/T” boundary marking the end-Cretaceous extinctions).  This event 65 million years ago was the result of an asteroid impact which triggered a global ecological catastrophe, most famously taking out the dinosaurs.  Megan and I want to see what happened to the community of organisms which bore and drill shells and other hard substrates.  Some of the best exposures of rocks associated with this extinction are found here in southern Alabama and neighboring Mississippi.

My friend and colleague Paul Taylor of the Natural History Museum in London is here with his PhD student Caroline Sogot (University of Cambridge) to investigate similar patterns in the other hard substrate faunas across the boundary, especially bryozoans.  We have joined forces so that we can most efficiently measure sections and collect specimens, many of which we will be sharing in later laboratory analyses.

Tomorrow is our initial orientation in the field.  We have been joined by Peter Harries of the University of South Florida and two of his graduate students, and in the morning we will meet Jon Bryan of Northwest Florida State College.  Peter and Jon are Cretaceous experts who know the local outcrops and are enthusiastic about the chance to talk paleontology for days on end!

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My New Best Friend, Betty Lou

The weather was beautiful today – slightly overcast, brisk, perfect field weather!

We began at an outcrop along the side of a road, where we debated about the origin of these coarse-grained layers in the diabase. The alternating bands of coarse- and fine-grained diabase seemed so regular that we even measured a section. (How unconventional for a petrologist!)

We spent most of the day sampling at the quarry. I could just imagine myself standing in the middle of a sill, surrounded by molten magma and crystal mush!

The beautiful textures in the wall are from layering of plagioclase and pyroxene in the diabase. This wall is about 15 feet tall. The quarry foreman told us that this stone is highly prized. They ship most of it to Italy, and it costs ~$4000 to make a countertop out of it.

Here's a closer view of the layers in a random cut block.

But the best part of the day was that we got to meet Betty Lou. Betty Lou is a Milwaukee Manta-III core drill, my new best friend! She came with Loretta from Lock Haven University.

Loretta and Tim (West Chester University) use Betty Lou to drill a core through the top of the diabase sheet.

Here's a close up of Betty Lou at work.

And here’s a video of Betty Lou in action.

Loretta shows off one of the many cores that we collected today.

The quarry workers were extremely friendly and accommodating, helping us in every way possible. Here’s a video of how they relocated the generator for us so that we could power Betty Lou on one of the lower levels.

I even managed to snap a photo of something my colleague, Dr. Judge, would have enjoyed: slickenfibers!

It’s hard to believe that I only have one more day of sample collecting and processing! We’ll be visiting another road cut and quarry tomorrow, then it’s off to the lab to slab the samples for geochem.

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Planning for a Day in the Field

I officially started my summer field work today! Unfortunately, here in West Chester, PA, it rained all day. That didn’t keep us from being productive, though. Lee Ann and Tim (from West Chester University) and Loretta (from Lock Haven University) and I began the day by visiting the quarries that we’ll be working in tomorrow. We spent the afternoon developing a plan for the rest of the week. It goes a little something like this:

The Plan

This really isn't the plan, but it is a map of all of the sites that we're interested in.

Lee Ann set out all of her samples from these locations and let us play in the lab all afternoon. We immersed ourselves in diabase, so much so that we nearly forget to break for dinner!

Diabase samples

A table topped with diabase hand samples, thin sections, maps, and chemical data = heaven.

Diabase thin section

Action shot of Lee Ann adjusting the microfiche viewer to get the best image of a diabase thinsection.

You would think that a day of discussion would clear things up, but I’m more overwhelmed than ever! I realize that I have so much to learn about the emplacement and evolution of these rift-basin dikes and sills. I typically think of these large intrusions as composite structures, formed by multiple pulses of magma, but I wonder if I’ll be able to recognize evidence of this in the field? How did the complex plagioclase-pyroxene layers form, and why are they different in different parts of the sill? And what are the mafic channels that cut across the plagioclase-pyroxene layers? Fortunately, I have wonderful and experienced (not to mention patient) colleagues who are seeking answers to the same questions. Some insights, I hope, will be gained by whole-rock geochemistry (as long as my sampling strategy works). Whew! Are all new projects as exciting as this?

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Knowing how to pick your field day

Compare these happy and warm Sed/Strat students to the freezing Petrology group in the previous post. It is all a matter of choosing the right part of April for fieldwork in Ohio. Comes with experience, I suppose.

Andrew Collins, Nick Fedorchuk and Travis Louvain measuring a section of the Logan Formation (Mississippian) in the Miller Lakes area of Wooster. The striped sticks are low-budget Jacob Staffs divided into tenths of meters.

Houston Hoskins, Megan Innis and Sarah Appleton also measuring and describing the Logan Formation at Miller Lakes. This is a class exercise to learn how to construct a simple stratigraphic column.

Sarah Appleton reaching high as she describes a portion of the Logan Formation with interbedded very fine sandstones and quartz-pebble conglomerates. These beds were deposited in the proximal portion of a deltaic complex with the conglomerates representing distributary channel sediments. Marine fossils such as crinoids, brachiopods and bivalves are found in both the sandstones and conglomerates.

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Tough Field Trips

I heard that the Sed-Strat field trip was canceled today due to rain. Hmm… I seem to remember a certain Wooster Geology course taking a field trip on a cold, snowy Saturday just a week ago.

Who's that out in the field on a cold, snowy Saturday in April? Petrology.

Yep. Hard Rock = Hard Core! Just saying.

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Science Day and Expanding Your Horizons

The Geology Department has been busy reaching out to the community lately. On Saturday, April 17, the College hosted its annual Science Day. GeoClub invited the community to dig for dinosaurs in a sand pit and witness an erupting volcano. See the story in the April 20 edition of the Wooster Daily Record (here’s a link if you happen to have a subscription).

After 4 years of a Wooster Geology education, senior Palmer Shonk ('10) demonstrates his ability to play in the sand.

Today, local middle school girls joined Geology faculty Meagen Pollock and Shelley Judge and several Geology majors to see if they could outrun a dinosaur. The girls measured the stride and size of dinosaur footprints to calculate the speed, then raced to see if they could beat it.

The situation: T-Rex chases Stegosaurus.

Ana helps one of the girls measure the size of the T-Rex footprint.

Melissa helps one of the girls measure the stegosaurus' stride.

Afterward, we played with rocks, minerals, and fossils. The girls got to choose one to take home.

Shelley Judge talks rocks with the Expanding Your Horizons Girls.

Polished stones and agates were today's momentos.

We even had time to demonstrate the use of a rock hammer.

And time to tell (bad) Geology jokes!

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Wooster Geologists Participate in the Senior Research Symposium: A Celebration of Independent Study

WOOSTER, OHIO–Several of our senior geology majors gave poster and oral presentations in the 2010 Senior Research Symposium today.  We are very proud of their accomplishments and the skills they have in articulating their projects to a very diverse audience.  It was a good day for the department.

Kelly Aughenbaugh delights in answering questions about her topic: "Reconstructing Late Holocene Glacial Movement in Muir Inlet Glacier Bay, Alaska."

Colin Mennett gave an oral presentation on his project: "Decline in Alaskan Yellow-Cedar: Tree-Ring Investigations into Climatic Responses and Possible Causes, Glacier Bay, Alaska."

Bill Thomas presented: "Petrographic and Mapping Analysis of Volcanic Tuffs in the Green River Formation Cuestas, Sanpete Valley, Utah."

Palmer Shonk explains to Anna Mudd his research: "Paleoecological Reconstruction of the Late Silurian (Pridoli) Äigu Beds of Saaremaa Island, Estonia."

Rob McConnell and his poster titled: "Paleoenvironmental analysis of the Silurian Jaani Formation on the island of Saaremaa, Estonia."

Travis Brown describing his work: "Directly-controlled lichen growth curves for western Spitsbergen, Svalbard."

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A pleasant spring afternoon of geology in Ohio

The College of Wooster 2010 Sedimentology & Stratigraphy class in Spangler Park near Wooster, Ohio. Small classes are such a delight!

WOOSTER, OHIO–I let my Sedimentology & Stratigraphy class talk me into an afternoon field trip to Spangler (or Wooster Memorial) Park just west of town. It was a perfect day of sunshine and cool breezes. While I made plans to measure sections and do other formal geological work, we ended up just enjoying the creek, birds, flowers, rocks, fossils, trees and other delights of Ohio in the spring. We could not have found a better way to celebrate Earth Day.

With the fancy nails of Megan Innis for scale, this is a granitic dropstone in a greenstone known as the Gowganda Tillite. In one of those wonderful geological twists, this rock is a glacial deposit formed in Ontario, Canada, 1.8 billion years ago. It was much later carried to Ohio by a Pleistocene glacier. The dropstone is thus at least twice-removed by ice from its original source.

The class crossing Rathburn Run which flows through the park. The creekbed has many fossiliferous pieces of sandstone, shale and limestone.

An Eastern Garter Snake (Thamnophis sirtalis sirtalis) on an oak leaf in Spangler Park.

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Lava pour!

A cauldron of lava poured onto an angled surface at Syracuse University. Photograph courtesy of Jeff Karson, Department of Earth Sciences at Syracuse.

SYRACUSE, NEW YORK–Today I gave a presentation at Syracuse University as part of the fifth annual Central New York Earth Sciences Student Symposium.  My topic was the rise of modern marine ecosystems in the Jurassic.  Exciting enough, of course, but the real fun was in an event which caught me by surprise: a “lava pour” organized by Professor Jeff Karson with the Sculpture Department at Syracuse.  (This is a type of interdisciplinarity I hadn’t seen before!)

The pour, as they call it, began with the addition of about 100 pounds of basalt (collected in Oregon where they have plenty of it) into a hardened steel cauldron.  The cauldron is then lowered into a below-ground furnace and heated for about four hours until all is incandescent.  Several people in protective gear (it would not protective enough for me, though!) open the furnace and attach a winch to the cauldron and lift it to the surface.  At this point the crowd (including me) had been pushing as close as allowed to the furnace.  We immediately backed up when the blast of heat from the cauldron — which was glowing like the sun — struck us.  Molten rock is serious stuff.

A bit of the lava was first poured into a porcelain pipe bent like an elbow with the lower part ending in a large basin of water.  The pipe had been plugged at the base with wax so the lava would build up before flowing through to the water.  The idea was to make a lava pillow, a type of flow structure made when a natural flow meets water as under a glacier, in a lake or in the ocean.  (See the natural pillow lavas studied last summer by the Wooster Iceland Team.)  The wax immediately and explosively ignited, sending a spout of flame upwards which took everyone by surprise (including the crew).  The fire was short-lived, though, as the lava flowed through into the now-boiling water.

The second pour was onto a cold rock monitored by a digital remote thermometer to record its cooling rate.  This time the lava poured out like syrup, making a flat, bubbling sheet which quickly grew a dark crust which spattered tiny glass shards as the cooling bubbles burst.

The third and final pour was onto blocks of dry ice, apparently to simulate the surface of Mars.  (Really.  Not just to “see what happens”.  This is professional geology, after all!)  The lava hit the dry ice with an extraordinary hiss and then skittered off onto the sand below.  Apparently the vapor built up immediately by the rapidly-sublimating ice did not allow the lava to stick or even stay on the ice itself.  The result was ropy strings, droplets and “angel hair” of cooled lava.

Afterwards, when the cauldron had been scrapped empty and the heat had dropped to a tolerable level, we gathered around the three pour sites and marveled.  The flow on the rock slab continued to bubble and crack, producing some exquisite brown fragments of almost-transparent glass.  We picked up a few cooled pieces and tried to imagine this process scaled up to natural proportions.

Thank you to Jeff Karson for such an innovative idea, this lava pour, and sharing it with all of us.  Way cool.  Mike Cheatham has posted a webpage of photos showing our lava pour in its stages.

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