jacfalstu lujvo

x1 is a waterfall


In notes:

pupsu
x1 is a waterfall (geological and hydrological, semi-permanent feature) with source/flowing fluid x2 (fluid need not be water), with rock/terrain characteristics/grade (slope)/features x3 in potential (gravitational well/field) x4; mass/quantity of fluid x2 flows over feature x3 so as to fall /tumble down it (continuously)