A question puzzling astronomers for many decades has been whether Mars ever had substantial liquid water. An idea put forth in 1991, based on two long lips of rock that resembled ancient shorelines, posited ancient oceans that covered roughly one third of Mars. One key characteristic of a shoreline is that its whole extent must be at the same elevation since the surface of any putative ocean would be at a constant elevation. This detail muddied the ancient-ocean scenario for the rock formations because detailed topographical maps revealed that “shorelines” were much “hillier” than expected.
A recent article in Nature explains why this might be. The small mass of Mars permits rather large volcanic buildup—one example is the Tharsis region, which formed early in Mars’ history. The large mass of such regions disrupts the stability of Mars’ rotation, so the mass rapidly moves toward the equator to minimize the rotational energy of the planet. Scientists refer to this movement as “true polar wander” and it is not to be confused with well-established plate tectonics.
The motion of such a large mass of Mars’ surface deforms a large fraction of the surface, changing the topography. The authors of the article demonstrate that such a true polar wander event would deform an ancient Martian shoreline and yield the hilly structure seen today. Coupled with results obtained with the remarkable Mars Rovers, the evidence is mounting that Mars indeed had an ancient ocean that disappeared more than 3 billion years ago.
I have discussed the implications of water on planets for RTB’s creation model previously. Here, I want to focus on the polar wander events. Such an event today would certainly cause major problems for larger-bodied animals. However, it seems such an event did occur on Earth around 800 million years ago (when only single-celled organisms inhabited Earth), and it sent Earth into an extended period of time where glaciers covered nearly the entire planet. Shortly (at least on geological timescales) after thawing, the Cambrian Explosion occurred, introducing a huge, diverse population of more-complex multicellular animals into Earth’s biosphere. Such a large-scale introduction of life had not occurred before nor has one occurred since. RTB’s creation model would posit this event as one of the critical steps needed to prepare Earth for advanced life, and it serves as a marker of supernatural, providential care of God for his creation.