Can You Spot the Difference? The Slowly Changing Surface of Mars

How different is the surface of Mars today compared to one thousand, a hundred thousand or a million years ago?  The photo below was snapped by the Curiosity Rover which has spent several years trekking across an ancient lake-bed inside a large crater on Mars.  It is a barren, forbidding but strangely familiar and beautiful scene.  Looking out across this cold and dry landscape one might wonder, if this was once a lake how long ago was it that water filled this crater.  When did the water disappear and how long did it take for the sediments that were laid down in that lake to erode to the exact point that we witness them today?

To address those broad questions, let me first address a more specific question:  What if you had been walking on Mars 6000 years ago at this very spot that the Curiosity Rover was positioned when it took this picture. What do you think it would have seen?  What differences do you think you could spot between a photo taken at that time and the one taken in the present?

A hillside with thousands of wafer-thin layers of rock on Mars.  Taken by the Mars Curiosity Rover.  Image: JPL/NASA-Caltech 2015
A hillside with thousands of wafer-thin layers of rock on Mars. Taken by the Mars Curiosity Rover. Image: JPL/NASA-Caltech 2015

I have zoomed in on one section of this rock outcrop to show you the complex pattern of erosion that has taken place.  These thin slabs of rock projecting into the thin martian air are less than one inch thick.

A bit closer view of the thin layers of rock that have eroded into sheet of rock that jut out from the rock wall in gravity defying ways.  Image:  JPL/NASA-Catltech
A bit closer view of the thin layers of rock that have eroded into sheet of rock that jut out from the rock wall in gravity defying ways. Image: JPL/NASA-Catltech

Consider the following question:  How far into the future or past would you have to travel in order for you to spot any differences with what we observe today?

Scientists that study Mars have provided evidence that if you were to this picture taken today beside one taken 6000 years ago there would be few obvious differences.

But what makes scientists confident that so little has happened on Mars for thousands of years?  The Curiosity Rover has provided, through some clever methods detailed below, the first estimate of both the age of some Martian rocks and the pace of erosion of that those rocks have experience over time.

The restaurant kids meal activity "spot the differences"  has many android app versions now including this one by ??.   I expect it would take a keen eye to notice the difference in a 6000 year old photograph of Mars and one taken today.
The restaurant kids meal activity “spot the differences” has many android app versions now including this one by CoRa games available at Google Play. I expect it would take a keen eye to notice the differences in a 6000 year old photograph of Mars and one taken today.

What has Curiosity determined about how fast rocks at this location on Mars have been eroding for the past 6000, 100,000 or even millions of years?  Data obtained by the Curiosity Rover allows us to estimate that these rocks are eroding about 1/2 inch per thousand years.*  Read that again, just 1/2 inch of the surface of rocks are being eroded over a 1000 years.  To erode a foot of the rocks shown in the picture above could require 24,000 years under current environmental conditions.

It is the environmental conditions on the surface of Mars that cause such low rates of erosion. The only erosive forces active at this site are winds laden with dust, thermal contraction and expansion, bombardment by high-energy cosmic radiation, and possibly some chemical weathering.  None of these forces can work quickly in the thin, cold atmosphere of Mars which is devoid of many chemically active molecules.  Under present conditions measured directly by the Curiosity Rover, erosion of 1/2 inch per thousand years seems almost too good to be true.  Nonetheless, these rates of erosion suggest that the spectacular geological features observed in Gale Crater, where the Curiosity Rover now resides, have not changed much in hundreds of thousands and even millions of years.

The very slow pace of change on the surface of Mars is power evidence that Mars’ surface is very ancient.  In fact, it is far older than the surface of the Earth which is far more rapidly eroded and then replaced by plate tectonic forces which force sedimentary rocks up into large mountain chains.

Mars Geology in the Context of Young Earth Creationism

Many literal six-day creationists believe that not only is the earth a mere 6000 years old but the Universe, and thus Mars, are also only a few thousand years old.   For them the features of Mars present a bit of a conundrum.  If Mars is only 6000 years old and we took a photo of the planet the day after it’s creation would it look completely different or would we have difficulty spotting the differences?  Most young-earth creationists believe that Mars could not have appeared as it does today because they believe that the great scars—craters—on its surface could not be part of that “perfect” original creation.  Hence, they believe that it it once was a different place with water filled basins and a thicker atmosphere.  That very different planet then must have undergone a radical transformation not long ago.

When they look at the layered rocks in our photo on Mars what is their response?  They propose that Mars must have experienced far different conditions in the recent past allowing for vastly higher rates of erosion (see: Young Mars Creationism).

Yes, it is possible that conditions in the past were different than they are in the present. In fact geologists are convinced that Mars has indeed experienced a different climate in the past, though they believe this was over 500 million years ago.  But could conditions have been radically different only a few thousand years ago?  Almost certainly not.  The Curiosity Rover has provided additional data that confirms that the presently observed conditions on Mars have persisted well into the past.

Faced with the increasing evidence of massive amounts of sedimentary rock on Mars, what we could call Young Mars Creationists (YMCs) are quickly adopting a catastrophic recent origin of geological features of the planets including Mars.  They accept the satellite and rover-gathered evidence that water once flowed on Mars.  They can see that there are massive deposits of sedimentary rock, there are erosion featured that suggest large rivers and there are shallow areas that have rock types that are evidence of their formation in shallow oceans or lakes. For example here is Answer in Genesis’ geologist Andrew Snelling in 2007:

“There is no longer any doubt that the surface of Mars has in the past been covered by huge volumes of water which spread over vast areas. These resulted from cataclysmic outflows, which were also responsible for catastrophic erosion of channels and valleys, on a scale far greater than anything comparable on Earth, and deposition of sedimentary strata.”  Water activity on Mars: Landscapes and Sedimentary Strata.

I wrote about Snelling’s opinion in an earlier article (Global Flood on Mars: Where Did the Water Go?).  YMCs recognize that current rates of deposition and erosion cannot explain the present-day observed features of Mars so they invoke a catastrophic past.  You may wonder though, why not simply invoke supernatural/special creation? Why not say that God created just what the Curiosity rover is seeing today as it is?  This is know  as the appearance of age hypothesis and YMCs rightly resist claiming that God simply created all this evidence of a past history of Mars.  But being bound to an origins view that requires Mars to be very young forces them to find alternative explanations for the evidence of massive changes to the geological landscape of Mars.   Hence, the appeal to Noahic-like catastrophic conditions in the very recent past.

While it is agreed upon by all geologists that past conditions were very different from those present on Mars today.  However, there is no evidence to support the conjecture that conditions have been significantly different in the very recent past (less than 100,000 years).  A crater, filled with sediments that were then eroded to form the valleys we see today, speak to diverse conditions in the past but spread over very long periods of time. The conditions that allowed for the unique appearance of the rock formation the rover is examining today are clearly the product of long exposures of wind erosion.    How long?  Probably hundreds of millions of years of erosion at rates similar to those observed today as evidenced by the data collected by the Curiosity Rover (see below).

Let me make one last observation that supports the conclusion that Mars has not changed much over thousands of years.  Mars has been called the red planet for 4000 years.  The very fact that it has been observed to be red for that long tells us that the planet has been devoid of water and covered in red dust for that long. Hence, wind erosion has been the only significant game in town with respect to erosion. Had there been a huge flood there 4500 years ago as YMCs propose then there would be massive amounts of water vapor in the atmosphere following that flood and the planet would not have looked red to the ancients who first observed the planet in the night sky.

* For more details about how data collected from the Curiosity Rover allowed scientists to estimate not just the the current rate of erosion on Mars but also estimate past rates erosion over hundreds of thousands of years see my article: Ancient Mars–Cosmogenic Dating Methods Allow Estimates of Erosion Rates on Mars.

Other articles about the Mars and Creationism:

My Interview with a Martian: A Story of Origins
The Mars Curiosity Rover: A Geological History Detective
Diverse Geological Landscapes Found on Mars
Curious Geology: Stunning Images Reveal a Complex Mars
NH Notes: Curiosity Update – Scenes on the Way to Mt. Sharp
Curiouser and Curiouser: A Mars Curiosity Update
Cosmogenic Dating Methods Allow Estimates of Erosion Rates on Mars
NH Notes: Answers in Genesis and a Mountain of Extraterrestrial Dust
NH Notes: Did Wind and Dust Create a 15,000 Foot Mountain in Gale Crater?
Non-Martian Rocks on Mars: Finding Small Meteorites on another Planet
Finding Mars on Earth: A Conversation about Martian Meteorites
Curiosity Rover Update: Diverse Geological Formations on Mars
Global Flood on Mars: Where Did the Water Go?
NH Notes: Mars Takes Another Hit, Wishes it had an Atmosphere Like Earth

Image taken by the Curiosity rover in Gale crater on Mars. In the distance is the rim of the crater. Image: NASA / JPL-Caltech / Malin Space Science Systems

Featured image:  Animal Spot the Difference Android App by CoRa Games

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