What did the comparison between the plains and the hill samples reveal about the alteration processes?
Answer
The hill samples showed pervasive chemical alteration by heated, acidic fluids circulating through the rock matrix over time.
The materials on the plains hinted more at erosion and brief surface water contact, whereas the hill samples exhibited pervasive chemical alteration indicating that heated, acidic fluids had circulated through the rock matrix over time.

#Videos
Did Spirit really find hot spring deposits on Mars? - YouTube
Related Questions
What was the singular objective of the Mars Exploration Rover *Spirit*?In which vast Martian basin did *Spirit* successfully land in January 2004?What was the scheduled primary operational lifespan for *Spirit* in Martian sols?What feature provided *Spirit* with the most compelling geological story regarding past water activity?What type of mineralogical objects, often called 'blueberries,' did *Spirit* discover that suggested flowing liquid water?The rock nicknamed 'Zurich Swiss' suggested formation in which specific ancient environment?What technical failure caused *Spirit* to become permanently immobile at a location nicknamed 'Troy'?Which instrument was primarily used for taking extreme close-ups of rock surfaces and textures?How was the longevity of *Spirit*'s operation, which far outlasted its design life, largely attributed to engineering management?What did the comparison between the plains and the hill samples reveal about the alteration processes?