21 Formation Processes and Characteristics of Subglacial Bedforms beneath the Ice Sheets of Continental North America

Friday, 28 March 2008
8:00 AM - 10:50 AM

EVALUATING DRUMLIN MORPHOMETRY WITHIN THE PETERBOROUGH DRUMLIN FIELD, ONTARIO, CANADA

Paper number: 21-6
Program: THEME SESSIONS
Time: 9:30 AM – 9:50 AM

Authors

Abstract

The quantitative analysis of morphological data can provide valuable information on which to base interpretation of geomorphic processes and may aid in the resolution of ongoing debate regarding the origin of glacial landforms such as drumlins. This paper presents the results of spatial and non-spatial statistical analysis of over 1000 drumlins within the Peterborough Drumlin Field (PDF) of Ontario. The PDF, located 125 km north-east of Toronto, covers an area of over 5000km2 and contains many thousands of individual drumlins formed during late Wisconsin glaciation. The drumlins within the PDF have been interpreted both as erosional ridges associated with catastrophic subglacial meltwater floods and as geomorphological expressions of a deforming subglacial bed.

Drumlins were identified within a subsection of the drumlin field from 10m resolution Digital Elevation Model data created by the Ontario Geospatial Data Exchange in conjunction with air photos and remotely sensed data. The process of drumlin identification was designed as an automated process within a Geographic Information system to minimize any potential bias in landform characterization. Numerous morphological variables are calculated for individual drumlins and drumlin types from the resulting shapefiles.

Spatial and non-spatial quantitative analyses of morphological variables for drumlins within the PDF are conducted including Pearson Correlation Coefficient, analysis of variance (ANOVA), clustering statistics, visualizing kernal densities and neighbourhood analysis. Results show differences in directionality of drumlin long axes across the study area, identifying regions with complex ice flow histories, particularly close to the Lake Ontario shoreline, and raise the possibility of multiple phases of drumlin formation. Spatial variations in drumlin types across the study area show distinct patterns of the clustering.