Earth's Ancient Soil is Older Than Previously Thought, Similar to Martian Land

A new study from the University Oregon reveals that soil on Earth is older than scientists previously thought. In fact, it existed long before trees or lichens evolved on the planet, and is even similar to the soil that NASA's Curiosity rover found on Mars.

According to the study published in the journal Gondwana Research, the team of scientists closely examined the rocks at Karijini National Park in Australia's Pilbara region. The scientists discovered that the rocks in the area were not of marine origin but have evaporated on land. This breaks previous assumptions that the Earth's soil was completely barren during the time that the oceans were populated with life.

"Life was not only present but thriving in soils of the early Earth about two thirds of the way back to its formation from the solar nebula," said Retallack via Science Daily.

The team lead by paleontologist Gregory Retallack also found out that the mineral and chemical tracers in the rock show that they had experienced weathering in a "distant geological past." Using advanced imaging and analyses technique, the group closely observed at least five different kinds of microfossils from the ancient Australian landscape, which have distinct sizes, shapes and isotopic compositions. These microfossils include a spindle-shaped hollow structure of actinobacteria, which is responsible for the earthy smell of soil after decomposition.

Another interesting microfossil is a sphere-shaped structure. The said microfossil is similar to the purple sulfur bacteria, which can photosynthesize organic compound even without oxygen.

"With cell densities of over 1,000 per square millimeter and a diversity of producers and consumers, these microfossils represent a functioning terrestrial ecosystem, not just a few stray cells," Retallack said. He further explained that the existence of these microfossils in the soil plays an important part in Earth's ancient history as they are responsible for the carbon, phosphorus, sulfur and nitrogen cycles.

What's more interesting is that the soil samples found in Karijini National Park are "superficially similar" to what the Mars Curiosity rover uncovered from the red planet. The scientists said that this discovery could help humankind in learning and discovering life on Mars and other planets.