The Purple Scum Belts were bands of worlds dominated by "purple scum", located West of the Datum.

These Earths had neither multicellular life - such as plants and animals - nor cellular life with internal nuculi. Only the very simplest of bacterium existed, in mats and banks as well as in ponds. These worlds didn't vary much from one to another.[1]

The closest belt of these worlds to the Datum spanned from before Earth West 30,000,000 to around Earth West 35,000,000. This first band of worlds contained structures like stromatolites, mounds of bacteria built up layer by layer in the sunlight. These forms were capable of movement.[1]

There was a second, larger band of purple scum worlds from approximately Earth West 50,000,000[1] to Earth West 100,000,000.[2] The climate conditions here were similar enough to those of Datum Earth that humans were able survive without significant protective clothing.[1] This belt also contained green scum worlds.[2]

A third band was present from the end of the Cnidarian Belt (at around Earth West 110,000,000) to approximately Earth West 130,000,000.[2]

A fourth began after the end of the Anaerobic Belt and extended to about Earth West 175,000,000.[3]

Another belt of purple scum worlds spanned from approximately Earth West 190,000,000 to before Earth West 200,000,000.[4]

The Long Mars

The purple scum belts were discovered by Maggie Kauffman and her crew during the expedition of the Armstrong II and Cernan in 2045.[1][2][3][4]

On one of these worlds, a stromatolite-like structure crept on an unwary crewman who was taking samples with her back turned.[1]


  1. 1.0 1.1 1.2 1.3 1.4 1.5 The Long Mars - Chapter 22
  2. 2.0 2.1 2.2 2.3 The Long Mars - Chapter 23
  3. 3.0 3.1 The Long Mars - Chapter 30
  4. 4.0 4.1 The Long Mars - Chapter 34
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