The Cretaceous-Paleogene (K-Pg) boundary is a geologic record that marks the occurrence of one of the most important events in Earth’s history. At this time, approximately 66 million years ago, a mass extinction occurred, caused primarily by a meteorite impact. This also caused a change in global climate and widespread deposition of material ejected from the impact crater. Studying the K-Pg boundary can help us understand how Earth responds to catastrophic events. Currently, there are few continental records of the K-Pg boundary in South America, resulting in poor understanding of its effects there. One method for finding the boundary uses magnetostratigraphy (measuring the magnetic polarity of a rock, preserved from when it formed). Earth’s magnetic field has reversed through time, and these reversals are recorded in rock formations. Chron C29r is an interval of reversed magnetic polarity that encompasses the K-Pg boundary. Samples taken from strata in La Colonia Formation in Patagonia, Argentina, were analyzed to find their magnetic polarity, resulting in the magnetostratigraphy for that formation. I successfully identified Chron C29r in samples taken from La Colonia. This information will help us better understand the mass extinction, especially how prevalent it was in South America and the extent to which biodiversity in that area suffered.
