Wyckoff & VSA
Wyckoff's picture of the range edges: jumping the creek, backing up to it, and falling through the ice.
The creek is a wavy line joining the rally highs inside an accumulation range, like the bank of a stream that price has to cross. The jump across the creek (JAC) is the sign-of-strength move that breaks through it. A back-up (BU) follows: a pullback to the edge of the creek that should hold above it, often the last point of support.
In distribution, the ice is the matching line under the reaction lows. Breaking through it, often called falling through the ice, is the sign of weakness, and a weak rally back up to the underside of the ice is the last point of supply. The metaphor comes from Robert Evans, one of the later Wyckoff teachers.
For education only, not financial advice.