
Early Mars was covered in ice sheets, not flowing rivers: study - bookofjoe
https://phys.org/news/2020-08-early-mars-ice-sheets-rivers.html
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bookofjoe
>Valley formation on early Mars by subglacial and fluvial erosion

[https://www.nature.com/articles/s41561-020-0618-x](https://www.nature.com/articles/s41561-020-0618-x)

