The morphological characteristics of ribbed moraine

Ribbed (Rogen) moraines are large subglacially formed transverse ridges that cover extensive areas of the former Laurentide, Scandinavian and Irish ice sheets. Given their ubiquitous and conspicuous nature, it is surprising that their characteristics are poorly understood. To date, most ribbed moraine studies have been spatially restricted and rely on small sample sizes. Thus, published accounts of their characteristics are most likely unrepresentative of ribbed moraines generally. This study addresses this deficit by producing the first representative data set on ribbed moraine size, shape, pattern and distribution and we describe their spatial characteristics. Various remote sensing and GIS techniques were used to map ribbed moraines over a combined area of 81,000 km(2) in Canada, Ireland and Sweden producing a database of just over 33,000 individual landforms. In all, 25,082 ridges were mapped in two areas in central and northern Quebec (the Lac Naococane and River Kaniapiskau regions), 5637 in the Lake Rogen area of central Sweden and 2500 in north central Ireland. In comparison against the published accounts of ribbed moraine we demonstrate that some widely held assertions are inaccurate or untrue, and we show that ribbed moraine morphological characteristics are more complex than has been hitherto reported. Our data reveals they exist over a larger scale range than was previously stated. This study concludes by presenting a list of ribbed moraine characteristics and argues that formational hypotheses must account for these if they are to remain valid explanations of ribbed moraine genesis. (c) 2006 Elsevier Ltd. All rights reserved.