The influence of geological fabric and scale on drainage pattern analysis in a catchment of metamorphic terrain: Laceys Creek, southeast Queensland, Australia Jane Helen Hodgkinson ⁎ , Stephen McLoughlin, Malcolm Cox School of Natural Resource Sciences, Queensland University of Technology, Brisbane, Australia Received 24 October 2005; received in revised form 27 April 2006; accepted 28 April 2006 Available online 11 July 2006 Abstract The relationship between geological fabric and drainage patterns in the 81.8 km 2 Laceys Creek sub-catchment of the North Pine River catchment, southeast Queensland, Australia, is analysed using a new channel–ordination system. The Laceys Creek catchment is situated on the South D'Aguilar Block, which underwent metamorphism, faulting and uplift from the Late Carboniferous to Late Triassic. The catchment drains exposures of two main rock units, the Neranleigh–Fernvale Beds and the Bunya Phyllite. Both units are composed of metamorphosed deep-sea sediments that accumulated as an accretionary wedge during late Palaeozoic subduction of the palaeo-Pacific plate under the eastern margin of the Australian craton. The new channel ordination system used in this study allows improved classification of stream segments of equal prominence or rank in comparison to previous schemes. A 10 m contour digital elevation model (DEM) was produced within which drainage channels were digitised. Planar geological features, including bedding, faults, joints and cleavage, were mapped in the field and collated with data from previous geological mapping programs. Regional and local trends of geological fabric are reflected in the variable orientation of channels of different rank in the catchment. Cleavage and fractures are the dominant planar features of the Bunya Phyllite and these correlate most closely with the orientation of middle-order incised stream segments. In contrast, middle-order channels on the Neranleigh–Fernvale Beds most closely correlate with bedding, which dominates the fabric of this unit. Although anthropogenic factors exert local influence and climatic processes exert broad influence on the catchment, this study focuses on structural and lithological fabrics, which are the apparent dominant controls on middle- order channel orientations. Identification of congruent patterns between bedrock fabric and channel ranks is variable, depending on the scale and number of channels included in the analysis. Many low-rank channels correspond closely to the orientation of fine-scale bedding and foliation and these influences may not be detected by coarse-scale mapping. Understanding the extent of geological controls on the morphology of a catchment may assist geo-hazard identification, land-use planning and civil-engineering projects. © 2006 Elsevier B.V. All rights reserved. Keywords: Metamorphic terrain; Catchment; Channel orientation; Drainage pattern; Channel ordination; Queensland 1. Introduction 1.1. Background The relationship between geology and landforms has long been established (e.g. Hobbs, 1904, 1911; Zernitz, 1932; Twidale, 1980). Structure and slope are accepted Geomorphology 81 (2006) 394 – 407 www.elsevier.com/locate/geomorph ⁎ Corresponding author. E-mail address: j.hodgkinson@qut.edu.au (J.H. Hodgkinson). 0169-555X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.geomorph.2006.04.019