Scientists find ‘definitive evidence’ of ancient coastline on Mars

Scientists have discovered evidence of an ancient coastline on Mars, an advance that suggests the planet once may have had an extended period of warm and wet climate far different from its current harsh, cold terrain.

The findings, published recently in the Journal of Geophysical Research: Planets, indicates there are higher chances of finding traces of ancient microbial life on Mars.

“What immediately comes to mind as one the most significant points here is that the existence of an ocean of this size means a higher potential for life,” study co-author Benjamin Cardenas from the Pennsylvania State University in the US said in a statement.

The research also sheds light on the Red Planet’s ancient climate and its evolution.

Based on the new findings, scientists say the planet may have had a long period when it was “warm enough and the atmosphere was thick enough to support this much liquid water at one time.”

Scientists have long debated whether Mars had an ocean in its low-elevation northern hemisphere.

In the new study, researchers could show “definitive evidence” of a roughly 3.5 billion-year-old shoreline.

Analysing new terrain maps of Mars, they found over 6,500km (4,000 miles) of ridges likely deposited by a stream, and grouped them into 20 systems to show that the ridges are likely eroded river deltas or submarine-channel belts.

“On Earth, we chart the history of waterways by looking at sediment that is deposited over time. We call that stratigraphy, the idea that water transports sediment and you can measure the changes on Earth by understanding the way that sediment piles up. That’s what we’ve done here – but it’s Mars,” he added.

Researchers found substantial sedimentary accumulation of at least 900m (3,000 ft) thick that covered hundreds of thousands of square km on the Red Planet.

These findings, scientists say, are remnants of an ancient Martian shoreline.

The region, now known as Aeolis Dorsa on Mars, once contained an ocean and has the densest collection of fluvial ridges on the planet, they say.

“It was dynamic. The sea level rose significantly. Rocks were being deposited along its basins at a fast rate. There was a lot of change happening here,” Dr Cardenas said.

Researchers say the evidence of Martian sea level change indicated by the study is consistent with an extended warm and wet ancient climate on the Red Planet, not a mostly frozen early Mars.