Figure 10. Longitudinal profile of the Colorado River from river mile 176 to 200 (A) and 200 to 224 (B). The Spencer Canyon flow at river mile 246 is shown as an inset in part B. Schematic synthesis showing the extent of different-aged intracanyon basalt flows from river mile 176 to 246 is shown on top of part A. Remnants are projected onto the profile based on their lidar heights and color coded based on their age (solid fills show remnants with ⁴⁰Ar/³⁹Ar dates). Note that the ca. 100 ka (blue) and ca. 200 ka flows (purple) are interpreted to have entered the canyon at similar places. These flows exhibit some of the best-defined flow tops. The ca. 320 ka Whitmore flows (green) are interpreted to have originated from Whitmore Canyon and to have a high surface that existed from river mile 187 to 192. The bold lower orange line between river mile 179 and 191 shows where the orientation of the 725–475 ka maximum strath surface indicates fault block rotation (see text). Figure is vertically exaggerated 13 times.