(ORDO NEWS) — A study by a geologist at Monash University has provided new evidence of when high rates of erosion have occurred throughout Mars’ history.
The results of the study, published today in the journal Geology, indicate that Mars’ climate was much more erosive in the past, suggesting that there were steady periods of time when liquid water moved across the planet’s surface.
Scientists have long wanted to understand how Mars went from a state potentially more like today’s Earth to the desolate, inhospitable place it is today.
“If we want to know if there was life on Mars, we need to understand the history of sedimentary rocks,” said study lead author Dr. Andrew Gunn of Monash University’s School of Earth, Atmosphere and Environment.
“Our study determines the timing and rate of erosion and sediment accumulation throughout the geologic history of Mars in an entirely new way, and for the first time quantifies the degree of weathering of each of the rock types we see on the Martian surface,” he said.
“This is important because we show that the abundance of wind-blown sand into craters on the surface of Mars can be linked to the planet’s climatic history, opening up a new way to understand when, in geologic time, Mars might have been habitable.”
The researchers used a wealth of data to estimate the size and origin of sand deposits in the craters, including geological maps, climate modeling and satellite data. They synthesized and interpreted this data to understand the control and timing of erosion on Mars.
On Earth and Mars, there is a sedimentation cycle in which surface rocks are slowly eroded into sedimentary rocks, sedimentary rocks bury each other, new rocks are formed, and the process continues.
On Earth, the surface is being reworked by tectonics, erasing old deposits on most of the planet, but on Mars, sediment accumulations on the surface have largely survived to this day.
Rocks erode much faster when they collide with each other in a liquid compared to a gas, because the liquid can carry larger, heavier rocks. To obtain sediment that can be moved by the wind, it is often necessary that rivers first break up large rocks into smaller particles.
“Observation of high rates of accumulation during a certain period of the history of Mars indicates that then, most likely, there were rivers that eroded the material,” says Dr. Gann.
“A lot of evidence has been published previously for the existence of surface water in the past of Mars – this means that there was liquid water on the surface and an atmosphere to support it (i.e. conditions more favorable for life) – but when exactly and for how long this happened, while dont clear”.
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