A team of researchers from The University of Colorado have announced the discovery of definitive evidence that a lake once existed on Mars.

Scientists have always speculated that Mars once had water on its soil, and that the presence of water on the planet could mean that life once existed on the Red Planet.

The UofC team states that the lake might have been 3.4 billion years old. The lake outline and trenches suggests that it once covered 80 square miles, and could have been as much as 1,500 feet in places. The evidence was strengthened by the existence of “beach deposits” along the lake’s deltas.

“On Earth, deltas and lakes are excellent collectors and preservers of signs of past life,” said Research Associate Gaetano Di Achille. “If life ever arose on Mars, deltas may be the key to unlocking Mars’ biological past.”