Researchers from the UK-based team shed new light on Mars’ dichotomy, a boundary between its elevated southern hemisphere and low northern hemisphere. The discovery suggests that the edge of the dichotomy was eroded back by hundreds of kilometers, possibly due to an ocean occupying Mars’ northern hemisphere.
To visualize the Martian dichotomy, NASA has provided relief maps that show the entire southern hemisphere is elevated by over a kilometer, resting on a thicker crust. The boundary between these regions runs roughly along the equator, except in areas like Tharsis with volcanic activity.
The dichotomy’s mysteries revolve around its origin and purpose. Scientists propose various explanations, including an early form of plate-tectonics or impact scenarios. However, the existence of a warmer, watery past and potential ocean in Mars’ northern basin remains debated topics.
Source: https://arstechnica.com/science/2025/01/field-of-mounds-on-mars-may-be-sign-of-erosion-at-the-edge-of-an-ocean