A drainage pattern that has been established on an earlier surface (perhaps conformable with the immediately underlying strata, and standing well above the present landscape). Subsequently the pattern was lowered by river incision so it now lies across geologic structures to which it bears no relation.
Geography
If a drainage pattern develops on a non-resistant mass covering a buried, resistant bedrock, and if base level falls enough, the drainage will cut into the bedrock in the established pattern (Douglass and Schmeeckle (2007) Geomorph. 84, 1–2).