Research press release


Nature Communications

Planetary sciences: Martian rocks that roll



今回、Douglas Jerolmackたちは、プエルトリコと米国で実施された河川によって運搬された中礫の調査に加えて、数々の実験を行い、中礫の形状だけで中礫の運搬距離を推定できることを明らかにした。Jerolmackたちのモデルは、地球での検証を経て、火星の岩石層で見つかった中礫の解釈に用いられた。


Rounded pebbles on Mars were transported for tens of kilometres in a river, suggests a new study published in Nature Communications this week. This study makes use of a new technique that may help estimate the distance travelled by pebbles and small particles on other planets.

The discovery by the robotic rover Curiosity of small rounded pebbles in rock formations on Mars suggested that there were streams or rivers flowing on our neighbouring planet in the past, but interpretations regarding these have been uncertain. Reconstructions have suggested that the pebbles became rounded as they rolled, slid and hopped along a river bed, but how far they travelled has not been quantified. Pebble shape can be used to infer the amount of mass lost during particle transport by water, and this mass loss equates to the amount of transport experienced by the pebble.

Douglas Jerolmack and colleagues used experiments as well as investigations of river-transported pebbles in Puerto Rico and the USA to show that the distance travelled by a pebble can be estimated using shape alone. They validated their model on Earth before using it to interpret the pebbles found in the Martian rock formations.

Once combined with future studies that analyse wind-transported particles, this work will help to improve our understanding of dune activity on present-day Mars.

doi: 10.1038/ncomms9366

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