For Starters | Digging Into History
This January three Colby geology majors accompanied Professor of Geology Robert Gastaldo on a National Science Foundation-funded research trip to South Africa’s Karoo Basin. Their goal? To collect samples of sedimentary rock that will be used to gain fuller understanding of the Permian Mass Extinction—the largest mass extinction in history, about 250 million years ago. It has been believed that the extinction was one event, but new research by Gastaldo indicates that it may have in fact been two separate events—land and ocean. The student researchers blogged so others could go along for the ride. Here are some excerpts.
First Days of Field Work
Posted Jan. 8, 2012, by Tara Chizinski ’14
So we have now been in the field for two days. After a long drive on Friday we arrived in the Karoo at Ganora Guest Farm. The farm is going to be our home for the next two weeks and it is a beautiful oasis in the middle of the desert. We found a locality two days ago, Tweefontain [near Nieu Bethesda, a small oasis town where the famous Owl House is the attraction], which has been described in previous papers about the area. Today we spent a long day in the field at this locality. Our goal is to describe the layering of rocks in the area that supposedly extends 100 meters in thickness. We began with rock beds near the bottom of a gully carved out by a stream that is currently dry. We worked our way upstream, measuring 1.5-meter sections at a time.
Something Is Up
Posted Jan. 10, 2012, by Mduduzi Langwenya ’14
Over the past four days, we were introduced to various field methods such as using the handy Jacob’s staff—a 1.5-meter rod with a leveling device to insure we are accurate in our measurements of bed thickness—to measure the thicknesses of stratigraphic sections. In addition, we are using the hand lens, sand-size gauge, and Munsell color chart to characterize different rock types. On Sunday, Kody and I started characterizing a stratigraphic section near Lootsberg Pass. We encountered the nontextbook type of primary structures, and we have since become experts in spotting the rock color 5Y 4/1, which is an olive gray. In short, the past four days have seen us become better geologists.
Green Rocks and Wildebeest
Posted Jan. 12, 2012, by Kody Spencer ’14
Besides measuring and describing rocks, we have had the opportunity to help determine the paleomagnetic orientation of these rocks by measuring the orientation of cores, which will later be taken to a lab to find the orientation of the magnetic grains in the samples. [When a sedimentary rock forms, the magnetic minerals in the sediment align to either magnetic north or south, depending on the dominant pole at the time. This information is locked into the rock, and it is possible to reconstruct the magnetic orientation of the planet over time showing the flipping of the poles.] This new information will help correlate time in different rocks across the globe based on the movement of the poles during Earth’s history.
And while the geology of the Karoo is fascinating, equally exciting has been seeing several different types of antelope, flamingos, zebras, baboons, and wildebeest. Almost anywhere you go you can see some kind of indigenous African animal from the road or our field site.
A Few Days of Rest
Posted on Jan. 15, 2012, by Tara Chizinski ’14
After a full week’s work we had a relaxing weekend off. Yesterday we spent the morning catching up on field notes and lounging around. Then we drove to Mountain Zebra National Park, about an hour’s drive from Ganora. We took an evening drive around the park, taking lots of great pictures of zebra, antelope, and many other animals. We hoped to see some Cape buffalo on our drive, but there were none to be found. However, we were greeted by a ranger at dinner who warned us to be careful on our way back to the rooms. Apparently a buffalo had broken into the camp! Some unhappy rangers were still stationed at the camp gate the next morning. We took another drive in the morning, seeing more zebra and baboons. We drove back to Ganora in the early afternoon, and had a relaxing time reading and enjoying the breezy day. Back in the field tomorrow!
Posted Jan. 19, 2012, by Kody Spencer ’14
After two weeks of measuring and describing the rocks for each of our sections, we have finally finished our fieldwork. Yesterday at New Wapadsberg Pass we finished Tara’s project and collected all the necessary samples. After lunch we drove back to Tweefontein to collect samples for my project and to go through the section to make sure we had written down everything correctly. Thanks to cores that had already been taken for paleomagnetism testing there were not many samples left to be taken, so we finished before noon and took a few paleocurrent measurements before we returned to Ganora for lunch and some rest before our big drive back to Cape Town on Saturday. A week from today we’ll be back at Colby!