The Mars 2020 Perseverance rover has explored the escarpment at the front of the western fan in Jezero crater, Mars, where it encountered a variety of rock units as in-place outcrops and as loose pieces of rock separated from outcrops, or “float” rocks. Comparing float rocks to in-place outcrops can provide key insights into the crater’s erosional history and the diversity of units in the Jezero watershed that the Perseverance rover cannot visit in-situ. Here, we used multispectral observations from Perseverance’s Mastcam-Z instrument to investigate the lithology and origin of float rocks found on the western Jezero fan front (sols 415-707). We identified four textural classes of float rocks (conglomerates, layered, massive, and light-toned) and investigated their physical characteristics, spectral properties, and distribution to interpret their source and constrain their mode of transport. We found that the conglomerate and layered float rocks are highly spectrally variable and altered with differing ferric and ferrous signatures, and they likely derived from local sedimentary outcrops in the western fan front. Massive float rocks are the least altered, exhibit ferrous signatures, and could have derived from local outcrop sources or more distal sources in the Jezero watershed. Massive float rocks separate into two subclasses: massive olivine and massive pyroxene, which likely derived from the regional olivine-carbonate-bearing watershed unit and the crustal Noachian basement unit respectively. The unique light-toned float rocks have variable hydration and low Fe-abundance, but there are no local outcrop equivalent of these rocks in the western Jezero fan or crater floor.

Granule- to cobble- sized clasts in the Glen Torridon region of Gale crater on Mars were studied using data captured by NASA's Mars Science Laboratory Curiosity rover between sols 2302 and 2593. The morphology and composition of clasts have the potential to reveal the nature and extent of erosional processes acting in a region. In this study, measurements of shape, size, texture and element abundance of unconsolidated clasts within lower Glen Torridon were compiled. Eight primary clast types were identified, all of which are sedimentary and can be compositionally linked to local bedrock, suggesting relatively short transport distances. Several clast types exhibit signs of aeolian abrasion, such as facets, pits, flutes and grooves. These results indicate that clasts are primarily the product of bedrock degradation followed by extensive aeolian wear.