Add to ORKG22 higher ground. Nevertheless the immediate banks of the river are almost everywhere picturesquely shaded by [thickets] of alder & dogwood & [balsampop] [balsam poplar] How the ground was prepared for the groves of oak & spruce [pines] [etc]. We have seen that most extensive groves of the valley bear a direct relationship to the largest & most invariable of the shadows cast—by the [constant] [in] all of the valley. This is because the largest accumulations of rocky debris are to be found [there], & the reason that the debris is more abundant [there] [than] when [there] is no covering of shadow is that after the grand central glacier that flowed down through valley filling it from wall to wall like a wind had gradually shallowed in the [g...