Here at ONU Geosciences, we recently were given a fantastic collection of fossils. The donation was made by the Rev. Ray Hawkins, an ONU alum from 1949. Rev. Hawkins collected rocks, minerals, & fossils for many years, mainly in Colorado. The collection includes excellent examples of both vertebrate & invertebrate species. We are pleased that Rev. Hawkins’s desire that his collection be available for future generations of students has come to fruition. The collection includes a variety of ammonite cephalopods, clams, snails, brachiopods, horn corals, bryozoans, trilobites, fish from the Wyoming Green River formation, shark & fish teeth, a fantastic phytosaur collection include a spectacular jaw with teeth, a rib, & a right humerus, horse and mammoth teeth, Mosasaur vertebrae, and insect fossils, among others. Even this hard rock guy thinks that phytosaur jaw is an impressive piece! Hawkins Fossil Collection video shot & narrated by Prof. Max Reams.
A quick photo of faculty & some of our graduates this year! Congratulations to all!
We’ve mentioned before that we are using the Big Map of North American geology, hanging in Reed Hall, as a way to demonstrate various geological ideas. Since the map is covered by a sheet of plexiglass, we can mark it up with dry-erase markers with annotations to show where various features can be found on the map. This time, however, we changed it up a bit.
This lesson, we focused on the extent of glaciers from the last Ice Age. And what better way to represent a sheet of ice than a large sheet of white paper? We have also continued to record the locations of large earthquakes that have struck this year.
A large sheet of white paper was used to demonstrate the extent of glacial ice in the last Ice Age.
The field trip we took over Spring Break to the Southern Appalachians has been reported in ONU News. We’re glad to see it, check it out & let us know what you think! Here are some more pictures of the group.
American conservationist John Muir was known for his love of natural areas, and once said “Go to the mountains and get their good tidings.” Today, our field trip to the Southern Appalachians comes to an end and we head back to Bourbonnais, IL. We return with new knowledge, measurements, photos, and experiences of the mountains. Field trips are an indispensable part of geological education. There is something about being there, out in the field, that opens up the mind to learning. I have seen students that seem to have learned more in just a few days in the field than in the entire rest of the semester. And it is more than just the terms and ideas and rational concepts that enter the brain. Being in the field, experiencing the mountains, has an effect that goes deeper into the human mind, to places where values lie. I think we have received their good tidings.
Whitewater Falls, on the North Carolina-South Carolina border. Cascades over the Toxaway Gneiss.
Mr. Woodall, a logger, needed his logs to float down the Chatooga River, but the rocks kept them jammed up. His solution was dynamite – blast out the rocks on the Georgia side and let the water flow. The exposure of rocks left behind is one of the best in the southeast.
The rocks here were folded a least half a dozen times, some at small scales, others much larger. Amphibolite layers are separated into boudins, unable to keep up with the stretching as the surrounding gneiss continued to be deformed. Quartz veins and pegmatite layers intrude as late stage gasps of activity.
This site is a geologic rosetta stone for the entire Eastern Blue Ridge, as the things seen here resemble the much larger structures across the region. Plus, its a gorgeous riverside escape from the hectic pace that defines much of modern life. People come here not only for spectacular geology, but also for a dose of tranquility. Enjoy the view here; more pictures on our return.
At the end of our fifth day, we arrived at the Vulcan Materials Rabun quarry, where the Rabun granodiorite is mined and crushed for aggregate stone. The operation makes big rocks into little rocks for concrete, paving gravel, asphalt, and other construction uses. We got to see the different piles of finished product, then got to go into the pit where recetly blasted boulders lie on the pit floor.
The stone is a black and white megacrystic rock, but inclusions of Tallulah Falls metasedimentary gneiss and calc-silicate layers form xenoliths. The quarry does not produce dimension stone, but if it did this rock would make one gorgeous kitchen countertop.
Wednesday, day 5 of our trip, we headed west from Ducktown, TN, where we had stayed the previous night. On Hwy 64 through the Ocoee Gorge, we began our trek across the Blue Ridge from one side to the other. This journey is a bit like traveling deeper into the depths of the Earth, because the metamorphic rocks exposed represent deeper and deeper rocks as you make your way east. Along this route, the Barrovian sequence of metamorphic index minerals gives a clear sense that the conditions that formed these rocks are changing. About 100 years ago, the Scottish geologist George Barrow did the first such expidition to map out how minerals in metamorphic rocks change across a large area. He discovered a sequence of minerals – chlorite-biotite-garnet-staurolite-kyanite-sillimanite – that serve to mark the increase in pressure-temperature conditions that affected the metamorphic rocks. This same sequence of mnerals, or slight variations of it, is observed in many metamorphic terranes. Here in the Blue Ridge, my students and I got to see a Southern Appalachian version of Barrow’s famous series.
Here’s a picture of several rocks that display one of Barrow’s index minerals – can you identify which one it is? Hint: brown, large, and a diamond-shaped cross-section. This mineral in normally twinned, which gives it its name, but here it is not.
On Tuesday, day 4 of our Southern Appalachian field trip, we drove up US-441 in Great Smoky Mountain Natl. Park to the trailhead for Alum Cave Bluff Trail, and headed up. The trail is about 2.2 miles to the bluff, and continues on another 3.3 miles to the top of Mt. Le Conte. Along the trail, mountain streams, rhododendron, and outcrops of highly cleaved and tilted phyllite provide great scenery. At Alum Cave Bluff, the phyllite is folded not once, but twice! The first generation folds are isoclinal, recumbent folds (interlimb angle = 0°, both limbs lie horizontally). The main foliation in the phyllite is parallel to the axial plane of these folds. Rigid layers, interlayered with the fine grained phyllite, are stretched out along the limbs into boudins and thickened in the hinges.
The second generation of folds are close, inclined folds. They tend to be pretty small, and only formed in the phyllite. We did not observe them in the more resistant layers. Their interlimb angles are a bit under 90°, and their axial planes tilt about 30°. Since they fold the earlier, isoclinal folds, a fantastic fold interference pattern can be seen in the cliff face. Can you see it in the pictures below by tracing the layers?