Fantastic Weather Makes Productive Field Days

ICELAND – Team Iceland made the most of the beautiful weather over the last two days. After spending all day in the field yesterday, we went back after dinner;  the lighting was just right to take GigaPan images of the field site.

Aleks ('14, Dickinson) and Ben (Dickinson) set up the GigaPan to take a panoramic image of the quarry.

Aleks (’14, Dickinson) and Ben (Dickinson) set up the GigaPan to take a panoramic image of the quarry.

This is a simple panorama made of three images stitched together. The GigaPan system allows us to merge over 100 images to produce a high-resolution image.

This is a simple panorama made of three images stitched together. The GigaPan system allows us to merge over 100 images to produce a high-resolution image.

Our plan is to couple the high-resolution GigaPan images with elevation information from the laser range finger. Here, Michael ('16, Wooster) and Ellie ('14, Dickinson) are recording the elevations of contacts along the quarry walls.

Our plan is to couple the high-resolution GigaPan images with elevation information from the laser range finder. Here, Michael (’16, Wooster) and Ellie (’14, Dickinson) are recording the elevations of contacts along the quarry walls.

Meanwhile, the rest of us are mapping and sampling the different units. Adam ('16, Wooster) and Aleks ('14, Dickinson) are ready to sample a glassy pillow lava.

Meanwhile, the rest of us are mapping and sampling the different units. Adam (’16, Wooster) and Aleks (’14, Dickinson) are ready to sample a glassy pillow lava.

Alex ('14, Wooster) describes a volcanic breccia unit.

Alex (’14, Wooster) describes a volcanic breccia unit. Photo Credit: Aleks Perpalaj

Liz ('16, Dickinson) carefully describes the mineralogy and vesicularity of a sample.

Liz (’16, Dickinson) carefully observes the mineralogy and vesicularity of a sample. Photo Credit: Aleks Perpalaj

Ben and I are having a blast working in the quarry (no pun intended).

Ben and I are having a blast working in the quarry (no pun intended). We’ve seen a number of interesting features that have our minds racing. Photo Credit: Aleks Perpalaj

We're currently puzzled over these large, light gray, columnar jointed features.

We’re currently puzzled by these large, light gray, columnar jointed features.

 

The puzzling features are associated with these steeply dipping pillow lavas, which might lead to some insights into their origin.

The puzzling features are associated with these steeply dipping pillow lavas, which might lead to some insights into the origin of the features and enhance our understanding of the formation of subglacial pillow ridges.

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Ancient islands

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LOGAN, UTAH–Today we explored the area around Promontory, in northern Utah. Among the many beautiful sites were these rocky, faceted hills that several thousand years ago. This particular hill was intriguing although inaccessible. (It is on a vast tract of land owned by the rocket company ATK. Trespassing is discouraged and no doubt at times very discouraging!) You can see this feature on Google Maps at 41° 37′ 21.11” N and 112° 21′ 42.28” W. Note the cone shape of the top that appears to be sitting on a flat layer beneath. That flatness is a beach terrace of ancient Lake Bonneville. It was formed 14,500 to 16000 years ago by wave action eroding away the hillsides, with the pinnacle exposed above water. (I love wave-cut terraces. Wooster Geologists have noted them before in this blog.)

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Here is a Google Earth view of the scene from the south and above. You can see the terrace cut deeply into the hill and extending to the sides. The highway below is where we stopped for the top photograph. Now note that curvy structure of rocks in the lower right of the above image. A close-up of it is shown below.

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This is a plunging fold. I can’t tell if it is a plunging anticline or syncline because I couldn’t visit it. You can make it out on the lower right of my photograph at the top of the page. These rocks are mantled with sediments from Lake Bonneville. In this case the sediments are coarse sand and gravels because of the lake energy at this shoreline. The exposed rocks are limestones, probably from the Paleozoic.

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On the other side of the valley, on the northwest end of the Wellsville Mountains, two terraces can be seen. The top one against the mountain is the 14500-16000 year-old one we saw throughout the Promontory region. The lower one is younger and made after lake levels dropped precipitously following a catastrophic flood through Red Rock Pass in southern Idaho (which I visited three years ago and recorded in this blog). Note on the lower left that it is being mined for sand and gravel. We see this throughout the area because these terrace deposits are so well sorted and useful in making concrete, building roadbeds, and the like. I learned recently that these kinds of deposits are in a category called “alloformations” because they are laid on top and against much older units.

Oh yes, and what else happened in Promontory, Utah? May 10, 1869!

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Mission Possible: Mapping the Quarry Walls

ICELAND – We spent Sunday morning discussing all of the features that we’ve seen during our reconnaissance investigations. After comparing notes, we defined several lithofacies, or mappable units with specific lithologic features. Our coherent lithofacies include pillow lavas, dikes, and intrusions while our fragmental lithofacies are units like volcanic breccia and lapilli tuff. By the end of the morning, Team Iceland was ready for their first group assignment: map a section of the quarry wall.

The students worked diligently to record comprehensive field notes.

The students worked diligently to record comprehensive field notes.

Image of a pillow lava that shows some of the features the students were looking for: radial columnar joints, glassy rind, interbedded hyaloclastite.

Image of a pillow lava that shows some of the features the students were looking for: radial columnar joints, glassy rind, and interbedded hyaloclastite.

The students celebrated the completion of their mission with lunch by large mining equipment.

The students celebrated the completion of their mission with lunch by large mining equipment.

 

 

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The Lodgepole Limestone Formation

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LOGAN, UTAH–Today we hiked up part of Logan Canyon along the south side of the Logan River. Towering above us on either side were massive limestone cliffs, as shown above. The thickest unit is the Lodgepole Limestone Formation (Lower Carboniferous, Tournaisian — about 350 million years old), which is well known throughout the northern Rocky Mountains. I’ve long admired its extent and consistency. It testifies to a shallow carbonate platform that extended from what is now Utah, and Colorado up into central Montana. In fact, correlative carbonates by other names are found from Arizona (the Redwall Limetone) well into Canada. I’ve also been impressed with those many paleontologists over the past century and a half who have managed to pry fossils out of its concrete-like matrix. When they do they have beautiful bryozoans, brachiopods and rugose corals. Some of the best are silicified and removed by dissolving the calcitic matrix from around them.

View of the northern side of Logan Canyon, Utah. The Lodgepole Limestone Formation makes up the major cliff on the right.

View of the northern side of Logan Canyon, Utah. The Lodgepole Limestone Formation makes up the major cliff on the right.

The Lodgepole Limestone Formation is part of the Madison Group of mostly limestones and dolomites. Most of these rocks are affected by karstic weathering, so the terrain often has disappearing streams, sinkholes and caverns.

While the carbonates of the Lower Carboniferous were being deposited in western North America, mixed siliciclastics dominated the east. Last semester’s Sedimentology & Stratigraphy class studied some of those rocks on their field trip to Lodi and the southern edge of Wooster, Ohio. It is always fascinating to look at very different sediments deposited at the same time in different places.

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Theory to Practice (Classroom in the Quarry)

ICELAND – Team Iceland is investigating the formation of subglacial pillow lavas on the Reykjanes Peninsula in southwest Iceland.

We are working on a an elongated pillow ridge, which erupted along a fissure system when the peninsula was glaciated.

Google Earth image showing the elongated pillow ridge that we are working on. The pillow ridge erupted along a fissure system when the peninsula was glaciated. 

Quarries along the ridge expose the internal structure of the subglacial deposits, revealing complex sequences of pillow lavas, intrusions, and fragmental units.

One of the active quarries graciously allowed us to use their break room for a morning overview.

Ben Edwards discusses the  geological goals of the project.

Ben Edwards discusses the geological goals of the project. Photo Credit: Jim Ciarrocca

We spent most of the rest of the day working in the inactive part of the quarry.

Team Iceland examines the base of a wall of pillow lavas and discusses the formation of hyaloclastite, the glassy fragmental material that spalls off the pillow rims.

Team Iceland examines the base of a wall of pillow lavas and discusses the formation of hyaloclastite, the glassy fragmental material that spalls off the pillow rims.

As we explored the walls, we found a lava cave. Alex Hiatt ('14) snapped a photo of the hibernating lava bears for Dr. Wilson.

As we explored the walls, we found a lava cave. Alex Hiatt (’14) snapped a photo of the hibernating lava bears for Dr. Wilson.

Aleks ('14, Dickinson) uses a GPS and a laser range finder to "shoot" the quarry walls.

Aleks (’14, Dickinson) uses a GPS and a laser range finder to “shoot” the quarry walls.

Adam Silverstein ('16) points out features on the wall for Aleks to shoot.

Adam Silverstein (’16) points out features on the wall for Aleks to shoot.

The day ended with some reconnaissance work in the active parts of the quarry after the workers had left.

Team Iceland poses with a a fantastic columnar jointed basalt they found on their reconnaissance investigation.

Team Iceland poses with a a fantastic columnar jointed basalt they found on their reconnaissance investigation.

 

 

 

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Wooster’s Fossils of the Week: Mackerel shark teeth from the Eocene of the Atlas Mountains, Morocco

OtodusCombined_585This week we highlight another gift to the Wooster Geology Department from George Chambers (’79). Among the many fossils that arrived in three delightful boxes were these shark teeth. They are from the extinct Mackerel Shark Otodus obliquus Agassiz, 1843. They were collected from the Eocene of the Khouribga Plateau in Morocco.
Otodus obliquus multiple 021313_585These shark teeth are rather common, although they are not often available in such fine preservation as these. What intrigues me is how they are collected and placed on the market. The Khouribga Plateau, west of the Middle Atlas Mountains, has some of the largest phosphate deposits in the world. These phosphorites (phosphate-bearing rocks) are mined in open pits by dynamite. After a blast, local commercial collectors rush in to gather fossils in the rubble before large processing machines arrive to process the ore. That can be a matter of minutes. They find many, many fossils in this phosphatic debris, mostly of reptiles and fish.
mackerelsharkThe lamnoid shark Otodus obliquus, a reconstruction of which is above, was a very large animal with some teeth over 10 centimeters in length. It may have been up to 9 meters long. Otodus obliquus was a “macro-predator”, meaning it was at the top of the food chain with a likely diet of marine mammals, fish, and other sharks. Its remains are found throughout the world in Paleocene and Eocene sediments. The fossil evidence suggests that this shark is an ancestor of the massive Carcharocles (“Megalodon”).

Thank you again, George, for these beautiful fossils!

References:

Agassiz, L. 1843. Recherches Sur Les Poissons Fossiles. Tome III (livr. 15-16). Imprimérie de Petitpierre, Neuchatel, p. 157-390.

Arambourg C. 1952. Les vertébrés fossiles des gisements de phosphates (Maroc-Algérie-Tunisie). Notes et Mémoires du Service Géologique du Maroc (Rabat) 92: 1-372.

MacFadden, B.J., Labs-Hochstein, J., Quitmyer, I. and Jones, D.S. 2004. Incremental growth and diagenesis of skeletal parts of the lamnoid shark Otodus obliquus from the early Eocene (Ypres) of Morocco. Palaeogeography, Palaeoclimatology, Palaeoecology 206: 179- 192.

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Pizza on the Pillows

ICELAND – Team Iceland has arrived! We have been joined by our collaborators from Dickinson College and now number 9 strong. The Dickinson crew arrived early on Friday morning, so we spent much of the day recovering from our overseas travel and preparing for fieldwork. In addition to obtaining vehicles and food, we met our Icelandic collaborator, Steinunn Hauksdóttir, at the Iceland Geosurvey (ISOR) to discuss logistics. (Steinunn also showed us their latest geological map of the northern volcanic zone. We promptly offered to map the rest of Iceland for them in exchange for bread and Skyr).

When the group awoke from their jet-lagged slumber, they were hungry for food and geology. So, we thought we’d try a twist on the introduction to the field area: Pizza on the Pillows. In a spur of the moment decision, we thought it might be fun to have an informal dinner at the quarries where we’ll be studying the formation of subglacial pillow lavas. We picked up pizzas and headed to the field.

Unfortunately, when we arrived at the field, the weather was perfectly Icelandic. Although you can't see it, the wind and rain would have made our pizzas soggy.

Unfortunately, when we arrived at the field site, the weather was perfectly Icelandic. Although you can’t see it, the wind and rain would have made our pizzas soggy. We got the cliff notes version of the overview instead.

We are creative bunch, though, and were still able to have a different kind of Pizza on the Pillows back at the hostel.

Team Iceland and their "Pizza on the Pillows" in the dry hostel dining room. Pictured from left to right: Michael ('16, Wooster); Aleks ('14, Dickinson); Ellie ('14, Dickinson); Liz ('16, Dickinson); Dr. Ben Edwards; Alex ('14, Wooster); Adam ('16, Wooster); Jim Ciarrocca (GIS, Dickinson).

Team Iceland and their “Pizza on the Pillows” in the dry hostel dining room. Pictured from left to right: Michael (’16, Wooster); Aleks (’14, Dickinson); Ellie (’14, Dickinson); Liz (’16, Dickinson); Dr. Ben Edwards; Alex (’14, Wooster); Adam (’16, Wooster); Jim Ciarrocca (GIS, Dickinson).

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Wooster Geologist on the Wasatch Front in northern Utah

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SALT LAKE CITY, UTAH–It may be a vacation, but even so, every geologist has the delightful duty of enjoying the local geological setting. The above image is looking south from the University of Utah campus in Salt Lake City along the Wasatch Front and the snow-dappled Oquirrh Mountains. We’re standing along the Wasatch Fault, which extends north-south from southern Idaho to central Utah. It is a large normal fault that marks the eastern edge of the Basin & Range Province. It is a beautiful setting for a campus.

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On Our Way to Iceland

BOSTON, MA – A bleary-eyed Iceland group left Wooster at 4 am this morning to begin the journey to the land of fire and ice. We’ve arrived in Boston and are comfortably checked-in. We are patiently awaiting our flight to Keflavik airport, arguably the most geological airport in the world.

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Proof that we really are leaving for Iceland in two hours! From left to right are Adam Silverstein (’16), Michael Williams (’16), and Alex Hiatt (’13). The gate agent assures us that we’ll see lots of rocks in Iceland. We sure hope so! Follow our adventures on the blog for the next two weeks.

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Wooster’s Fossil of the Week: An amphibian from the Permian of Germany

Apateon_pedestris_Odernhelm_Germany_fixedThe above skeleton is of the salamander-like Apateon pedestris von Meyer 1840 from the Lower Permian of Odernhelm, Germany. There are just enough of these tiny little bones to show the ghostly outline of this freshwater amphibian. It is our only amphibian fossil at Wooster, and it is another gift from the George Chambers collection.

Apateon pedestris is in the Order Temnospondyli, a group thought to be ancestral to the modern salamanders. They would have lived much like their descendants today, spending most of their time in creeks and streams and wet leaf litter. It grew to a maximum length of about nine centimeters. Its head was wide and flat, presumably to aid in swimming. Some specimens are preserved with soft tissues intact showing that this species had external gills as an adult, a classic example of paedomorphosis (as my History of Life students will tell you).

homo diluvii testis-1The skull of our tiny specimen reminds me of a younger, larger and much more famous Miocene amphibian that went for a time under the surprising name Homo diluvii testis, meaning “evidence of a human at the time of the Noah’s Flood”. A drawing of the skeleton is shown above.

Johann Jacob Scheuchzer (1672-1733)

Johann Jakob Scheuchzer (above) described and interpreted Homo diluvii testis in Lithographia Helvetica (1726). He was convinced it represented a person (more likely a child) who was drowned in the Flood of Noah and then entombed in the sediments. The critical page from his book is shown below.

HdtJohann Jacob Scheuchzer (1672-1733) was a Swiss medical doctor and somewhat of a naturalist. He certainly had a gift for seeing a human pattern in these bones that is lost on us today — the skeleton is obviously not that of any kind of mammal. It is likely he was far too enthusiastic about finding what he considered solid proof of the Flood and a member of the wicked generation nearly killed off by it. Here is a bit of poetry he included in his fossil description:

Afflicted skeleton of old, doomed to damnation,
Soften, thou stone, the heart of this wicked generation!

homo diluvii testis

Much later the famous French scientist Georges Cuvier (1769-1832) had at Scheuchzer’s fossil (above). He showed that it was, of course, an amphibian. The name for it now is Andrias scheuchzeri — a perpetual honor for its sincere but deluded discoverer.

References:

Fröbisch, N.B., Carroll, R.L. and Schoch, R.R. 2007. Limb ossification in the Paleozoic branchiosaurid Apateon (Temnospondyli) and the early evolution of preaxial dominance in tetrapod limb development. Evolution and Development 9: 69-75.

Fröbisch, N.B. and Schoch, R.R. 2009. The largest specimen of Apateon and the life history pathway of neoteny in the Paleozoic temnospondyl family Branchiosauridae. Fossil Record 12: 83-90.

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