Fig. 2: Muskox Valley LiDAR and topographic profiles.

a LiDAR-based hillshade spanning 2000 m of Muskox Valley coincides with the dashed white outlined area in Fig. 1. Top inset figure shows topographic cross-sections oriented perpendicular to the direction of flow located at the color-keyed dashed lines along the hillshade. Cross-sections have been normalized to the maximum elevation and ground station. The bottom inset figure shows power spectra of down- and cross-valley topographic profiles (“Methods”). The spectra are color-keyed to the areas denoted by the solid colored boxes along the hillshade. The top inset photograph shows the nature of gullied hillslope drainage emerging from the fronts of solifluction lobes. The white-filled dot is located in the center of the inset image. Channel stationing at 200 m increments is indicated by white dots and corresponds to the channel and valley profiles shown in 2b. A thin black line overlain on the hillshade traces the channel profile. Dashed white arrows along the valley margins highlight locations where tributaries merge into the valley; arrow thickness proportional to tributary drainage area. The white dotted line segment around the lake indicates inferred lake surface elevation in summer 1959 (see Fig. 4). Satellite image sources: Esri | Maxar (DigitalGlobe) | Earthstar Geographics | GIS User Community, Imagery ID: 10df2279f9684e4a9f6a7f08febac2a9. Coordinates are UTM projection, Zone 16. b Channel and valley elevation profiles derived from the LiDAR data, and valley-bottom Width-Depth ratios (open circles) (“Methods”). Channel elevation profiles correspond to the stationing line shown in 2a; valley profiles are drawn parallel to the valley orientation outside of the channelized regions of the LiDAR. The colors of the channel elevation profile correspond to the local average slope, calculated over a 20 m moving window. CH stands for channelized, and UC stands for unchannelized.