ICELAND – Team Iceland had a chance to explore Iceland’s capital city of Reykjavik today. Here are the photo highlights of their day:
ICELAND – Team Iceland had a chance to explore Iceland’s capital city of Reykjavik today. Here are the photo highlights of their day:
SALT LAKE CITY, UTAH–On the last full day of our Utah trip, we toured the Natural History Museum of Utah in Salt Lake City. It is in a spectacular place against the red rocks of the Wasatch Mountains and looking over the Salt Lake Valley. This museum has only been open since November 2011. Its exhibits are very up-to-date and modern. (My test for recent accuracy is whether birds are acknowledged as dinosaurs and if Australopithecus sediba is in the human evolution section.) I’d like to just share some images from the museum and encourage anyone in Salt Lake City to visit it.
Dr. Judge will be impressed with the attention paid to exhibits on the Green River Formation (Eocene). This tableau is designed to show animals in the water (below) and on the beach (above). Note the stromatolites on the shoreline representing some of the features she and her students have worked on in the Green River Formation.
Utah is extremely rich in Mesozoic vertebrate fossils. Here is an impressive skeleton of Deinosuchus hatcheri from the Cretaceous.
The dinosaur exhibit is world-class. Here is a wall of ceratopsian dinosaur skulls showing evolutionary relationships.
My History of Life students are well trained in sorting out major dinosaur groups by their pelvic bones. They could tell you, for example, if this is an ornithischian or a saurischian dinosaur.
And this set is of the other group. Can you see the differences?
It appears this dinosaur had barnacles for eyes!
Here is the classic paleontologists-behind-glass exhibit of a working laboratory. (I wonder why they never put working petrologists on display?)
The architects knew exactly what they were doing when it came to designing the building to take full advantage of the setting. The Salt Lake Valley is fully visible from every floor.
What a great place to end our little Utah excursion this year. The real Team Utah of Wooster Geology will be back in the state next month.
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.
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.)
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.
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.
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!
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.
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.
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.
ICELAND – Team Iceland is investigating the formation of subglacial pillow lavas on the Reykjanes Peninsula in southwest Iceland.
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.
We spent most of the rest of the day working in the inactive part of the quarry.
The day ended with some reconnaissance work in the active parts of the quarry after the workers had left.
This 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.
These 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.
The 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.
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.
We are creative bunch, though, and were still able to have a different kind of Pizza on the Pillows back at the hostel.
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.