The research, to be published in the journal Science this week, supports evidence gathered by Curiosity last year that indicated Curiosity's area of study was once covered in flowing water.
This new finding is especially satisfying as Mars pebbles bear a striking resemblance to their terrestrial counterparts (see the comparison, top).
PHOTOS: Mars Through Curiosity's Powerful MAHLI Camera
"These conglomerates look amazingly like streambed deposits on Earth," Williams added in a NASA news release. "Most people are familiar with rounded river pebbles. Maybe you've picked up a smoothed, round rock to skip across the water. Seeing something so familiar on another world is exciting and also gratifying."
Through analysis of the distribution of the pebbles of various sizes inside the conglomerates, Williams' team was also able to deduce that the pebbles formed in a river or stream with persistent, steady flow that likely carried the material over long distances before depositing it downstream.
"Our analysis of the amount of rounding of the pebbles provided further information," said co-author Sanjeev Gupta of Imperial College, London. "The rounding indicates sustained flow. It occurs as pebbles hit each other multiple times. This wasn't a one-off flow. It was sustained, certainly more than weeks or months, though we can't say exactly how long."