Quantitative geomorphological analysis of drumlins in the peterborough drumlin field, ontario, canada

Abstract

Drumlins are enigmatic subglacial landforms that have been interpreted to form by a number of processes, including incremental accumulation of till, erosion of previously deposited sediment, catastrophic meltwater floods, and sediment deformation. However, relatively little is known about the controls on drumlin formation, such as spatially variable glacial processes or substrate characteristics, and how these controls may be identified from variations in drumlin morphology within a single drumlin field. This paper explores a computational method that allows identification of drumlins and extraction of their morphological characteristics from existing topographic digital data for a portion of the eterborough drumlin field in ntario, anada. Spatial and non‐spatial analysis of the form and distribution of drumlins across the study area identifies drumlin characteristics such as size, elongation ratio, symmetry and long axis orientation and shows that drumlins are not randomly distributed across the region and their form characteristics have distinct regional trends. Kernel density analysis is used to identify the regional trends in drumlin characteristics. Factors that appear to influence the form and distribution of drumlins in the study area include sediment thickness, length of time beneath the ice, ice velocity and direction of ice movement. The distribution of particularly well developed asymmetric and elongate drumlins coincides with the location of a broad bedrock low and is interpreted to identify the former location of a fast‐flowing ice stream.

Key words:

• geomorphology
• kernel density analysis
• Peterborough drumlin field

Acknowledgements

Research was funded by Discovery Grants to Carolyn Eyles from the Natural Science and Engineering Research Council of Canada. We would like to thank Sean Fletcher, Luke Hunt, Kelsey MacCormack, Stacey Puckering, Jessica Slomka, Prateek Gupta and Julianne Bagg for assistance in the field, with drafting figures, taking photos, editing the manuscript and hours of discussion. The authors would like to thank Carrie Jennings, Matteo Spagnolo and Darrel Swift for their constructive review of the manuscript.