Alluvial diagram

The height of a block represents the size of the cluster and the height of a stream field represents the size of the components contained in both blocks connected by the stream field.

Alluvial diagrams were originally developed to visualize structural change in large complex networks.

Alluvial diagrams highlight important structural changes that can be further emphasized by color, and make identification of major transitions easy.

Alluvial diagrams can also be used to illustrate patterns of flow on a fixed network over time.

[1] The Users Flow feature of Google Analytics uses alluvial diagrams to graphically represent how visitors move among the nodes (individual pages) on a website.

An example of an alluvial diagram that illustrates how the scientific study of neuroscience coalesced from other related disciplines to form its own field.