Expression for an abrupt change in height

A cliff or precipice is at the boundary to an abrupt change in altitude.

Google:

cliff

a steep rock face, especially at the edge of the sea.

synonyms: precipice, rock face, crag, bluff, ridge, escarpment, scar,

related: shelf

I don't speak German, but looking at this page it seems to me Geländekante can apply to any abrupt change in "level".

Those examples range from "height discontinuities" of hundreds/thousands of feet (cliffs, Ayers Rock) to mere inches (kerb between road and pavement, small mismatch in a loading bay area). So I think the short answer is there is no equivalent "generic" word or common expression for this in English.

1: At the "geological" level there are lots of terms (cliff, escarpment, bluff, etc.), with the same or overlapping meanings.

2: Somewhere in the middle - usually from the "above" perspective, with emphasis on the danger of falling over the edge - are terms like precipice, drop.

3: At smaller scales (the most likely context where you'd need a more general-purpose term) the best bet is probably step (Mind the step = Don't trip over the upcoming small change in level).

If you are specifically referring to a change in height of a person (a human) - then we call that a "spurt", or more specifically a "growth spurt" - when a child grows inches taller, almost overnight.