The asymmetry of the planar shape of drumlins is an established paradigm in the literature and characterizes drumlins as resembling tear drops with a blunt (bullet-shaped) stoss end and a tapering (pointed) lee end. It is widely cited and never been seriously questioned. In this paper, the planar shape of 44,500 drumlins mapped in various regional settings from drumlin fields in North America and Northern Europe were objectively analysed by means of Geographic Information System tools. Two parameters were considered. The first (denoted here as Aspl) focuses on the relative position of the point of intersection between the axes of the maximum length and the maximum width. It is defined as the distance between the upstream (i.e. beginning of the drumlin) and the intersection point (measured along the longitudinal axis) divided by the entire length of the long axis. Results indicate that the intersection point of the majority of drumlins (64%) isvery close to the longitudinal midpoint (0.33bAsplb0.66). The second parameter (Aspl_A) is defined as the ratio between the area of the upstream half of the drumlin to that of the entire drumlin. Results show that for most drumlins (81%), the upper half area is almost as large as the down-half (0.45bAspl_Ab0.55). Taken together, these results concordantly indicate that drumlin planar shape has a strong tendency to be longitudinally symmetric and that the long-established paradigm of their plan form is false.

abstract = "The asymmetry of the planar shape of drumlins is an established paradigm in the literature and characterizes drumlins as resembling tear drops with a blunt (bullet-shaped) stoss end and a tapering (pointed) lee end. It is widely cited and never been seriously questioned. In this paper, the planar shape of 44,500 drumlins mapped in various regional settings from drumlin fields in North America and Northern Europe were objectively analysed by means of Geographic Information System tools. Two parameters were considered. The first (denoted here as Aspl) focuses on the relative position of the point of intersection between the axes of the maximum length and the maximum width. It is defined as the distance between the upstream (i.e. beginning of the drumlin) and the intersection point (measured along the longitudinal axis) divided by the entire length of the long axis. Results indicate that the intersection point of the majority of drumlins (64{\%}) isvery close to the longitudinal midpoint (0.33bAsplb0.66). The second parameter (Aspl_A) is defined as the ratio between the area of the upstream half of the drumlin to that of the entire drumlin. Results show that for most drumlins (81{\%}), the upper half area is almost as large as the down-half (0.45bAspl_Ab0.55). Taken together, these results concordantly indicate that drumlin planar shape has a strong tendency to be longitudinally symmetric and that the long-established paradigm of their plan form is false.",

keywords = "Drumlins",

author = "M Spagnolo and C.D. Clark and A.L.C Hughs and P. Dunlop and C.R. Stokes",

Research output: Contribution to journal › Article

TY - JOUR

T1 - The planar shape of drumlins

AU - Spagnolo, M

AU - Clark, C.D.

AU - Hughs, A.L.C

AU - Dunlop, P.

AU - Stokes, C.R.

PY - 2010/11/10

Y1 - 2010/11/10

N2 - The asymmetry of the planar shape of drumlins is an established paradigm in the literature and characterizes drumlins as resembling tear drops with a blunt (bullet-shaped) stoss end and a tapering (pointed) lee end. It is widely cited and never been seriously questioned. In this paper, the planar shape of 44,500 drumlins mapped in various regional settings from drumlin fields in North America and Northern Europe were objectively analysed by means of Geographic Information System tools. Two parameters were considered. The first (denoted here as Aspl) focuses on the relative position of the point of intersection between the axes of the maximum length and the maximum width. It is defined as the distance between the upstream (i.e. beginning of the drumlin) and the intersection point (measured along the longitudinal axis) divided by the entire length of the long axis. Results indicate that the intersection point of the majority of drumlins (64%) isvery close to the longitudinal midpoint (0.33bAsplb0.66). The second parameter (Aspl_A) is defined as the ratio between the area of the upstream half of the drumlin to that of the entire drumlin. Results show that for most drumlins (81%), the upper half area is almost as large as the down-half (0.45bAspl_Ab0.55). Taken together, these results concordantly indicate that drumlin planar shape has a strong tendency to be longitudinally symmetric and that the long-established paradigm of their plan form is false.

AB - The asymmetry of the planar shape of drumlins is an established paradigm in the literature and characterizes drumlins as resembling tear drops with a blunt (bullet-shaped) stoss end and a tapering (pointed) lee end. It is widely cited and never been seriously questioned. In this paper, the planar shape of 44,500 drumlins mapped in various regional settings from drumlin fields in North America and Northern Europe were objectively analysed by means of Geographic Information System tools. Two parameters were considered. The first (denoted here as Aspl) focuses on the relative position of the point of intersection between the axes of the maximum length and the maximum width. It is defined as the distance between the upstream (i.e. beginning of the drumlin) and the intersection point (measured along the longitudinal axis) divided by the entire length of the long axis. Results indicate that the intersection point of the majority of drumlins (64%) isvery close to the longitudinal midpoint (0.33bAsplb0.66). The second parameter (Aspl_A) is defined as the ratio between the area of the upstream half of the drumlin to that of the entire drumlin. Results show that for most drumlins (81%), the upper half area is almost as large as the down-half (0.45bAspl_Ab0.55). Taken together, these results concordantly indicate that drumlin planar shape has a strong tendency to be longitudinally symmetric and that the long-established paradigm of their plan form is false.