This study investigates students' conceptions of the causes and processes that form eskers and erratics, types of glacial and glaciofluvial landforms which to date have been little researched in geoscience education. The data collected for the study included 134 responses to an assignment completed by 12- to 13-year-old students in the Swedish national geography test in 2013. The responses were sampled and analyzed using qualitative content analysis. The findings show that many of the students held alternative conceptions regarding the causes of these landforms, which included landslides, meteor impacts and human activity. Although some students were able to give a scientific explanation that considered the possible causes and relevant processes involved in the formation of erratics, many students did not give a full account of these processes. Furthermore, only a few students were able to describe the relevant processes involved in the formation of eskers and were more likely to discuss alternative or glacial processes rather than glaciofluvial processes. Given the lack of research on students' understanding of glacial processes and landforms in geoscience and geography education, this study contributes with new knowledge of students' conceptions of eskers and erratics and makes a theoretical contribution to research on students' alternative conceptions and understanding of sequential and emergent processes in geoscience. The findings provide specific insights for teachers and are useful in the design of classroom practices that can change alternative conceptions and strengthen scientific conceptions.