Characteristics and formation of bedrock mega-grooves (BMGs) in glaciated terrain: 1 - morphometric analyses

Bedrock mega-grooves (BMGs) are subglacial landforms of erosion that occur in glaciated terrain various geological and (palaeo)glaciological settings. Despite a significant literature on BMGs, no systematic morphometric analysis these has been undertaken. This is necessary step towards exploring BMG formation successfully applied to other similar magnitude (e.g. mega-scale glacial lineations (MSGLs) drumlins). In this study, BMGs from ten locations across the world systematically mapped, sampled measured. Based 10th–90th percentile aggregated global population (n = 1242), have lengths 224–2269 m, widths 21–210 depths 5–15 elongation ratios 5:1–41:1, spacing between adjacent grooves 35–315 m. Frequency distributions for all metrics unimodal, strongly suggesting form single landform population. establishes as geomorphic entity, distinctive landforms. The variability their correlations within sites most likely reflect site-specific characteristics. At which associated with fast-ice flow, display largest dimensions (especially terms length, depth width) but lowest ratios, whereas formed under primary control occupy smaller size ranges higher ratios. Morphometrically, MSGLs plot different populations, being average 4 × shorter, 3.5 narrower, more closely spaced about 2 deeper. It suggested future research focuses numerical modelling experiments test rates bedrock lithologies varying glaciological conditions, adding body existing field-derived empirical observations. latter remains key validating controls over assessing efficiency mechanisms.