Tesserae are the stratigraphically oldest and geologically complex regions on Venus. Recent global climate models propose that Venus experienced Earth-like temperatures for most of its history prior to catastrophic global warming. This study tests for fluvial erosion prior to global warming by comparing valley patterns in tesserae with terrestrial stream patterns. Valleys were identified by margins of tesserae partially flooded by younger basaltic plains flows. Recognition of erosion in tesserae is a paradigm shift and has numerous implications. One such implication relates to the interpretation of lineaments sets in tesserae. Multiple lineament sets are characteristic of tesserae and are typically interpreted as the surface trace of fold crests, faults and grabens. However, the interpretation of erosion allows additional interpretations of lineaments as the exposed edges of sedimentary or volcanic sequences. PCA (Principal Component Analysis) can be applied to curving lineaments to calculate dips for such planar geological units and structures.