Knickpoint

A knickpoint, also spelled nickpoint, is a place along a river or channel where the slope of the bed changes abruptly, often appearing as a waterfall or a lake. Knickpoints form under the influence of tectonics, climate history and lithology: tectonic uplift and faulting can create a steep reach of channel, glaciation can leave a hanging valley where slope changes sharply, and differences in rock type erode at different rates to leave a break in slope. A drop in base level also triggers knickpoint formation, since the river responds by cutting into the landscape starting at the knickpoint, and that incision then migrates upstream at a rate that depends heavily on the size of the drainage area above it.