Magnetism, the Earth as a Magnet, and Seafloor Banding—How Much Magnetism is Enough?

Abstract

Although seafloor banding patterns are widely taught as a key piece of evidence for plate tectonics, little research has been conducted on student understanding of magnetism in a geological context. This study was conducted in two introductory geology courses to identify the effect of students' understanding of basic magnetism on their ability to build a simple conceptual model of seafloor banding consistent with the scientifically accepted model. Students were asked open-ended questions to elicit their reasoning about magnetism, Earth magnetism, and seafloor banding. Results suggest that many students in the study had weak or alternate models of basic magnetism. These models led students to reason incorrectly about magnetic interactions of the Earth's magnetic field and Earth materials during rock formation. Even students with robust magnetic models had difficulty applying them correctly to account for the origin of seafloor banding.