https://www.cnet.com/news/scientists-find-the-source-of-all-that-crazy-mars-dust/

Mars is looking pretty hazy these days thanks to a nutty global dust storm that sent one of NASA's rovers into hibernation. All that dust had to come from somewhere, and scientists believe they've found the main source. 

The over 600-mile-long (1,000-kilometer) Medusae Fossae Formation near Mars' equator traces its origins to long-ago volcanic activity.  A new study published in the journal Nature Communications calls out the wind-eroded Medusae Fossae as the single largest source of dust on Mars.