Suppose that Mars (being smaller than the earth) cooled off about 100 million years before the earth. life started, and evolved. Human life evolved on mars, and the inhabitants built great cities, like 21st century NYC. Suppose then , that the Martyains died off 9the atmosphere got too thin, the water dried up, and the sun’s UV radiation killed off all life. What trace of the martians would we find, after 100 million years? Would the Empire State building last 100 million years? Just wondering what the archaeologists of the first Mars Expedition will have to look for.
There was a similar thread posted about the Earth, thousands of years after the fall of civilization. The one answer that stuck with me was quarries–rectangular holes carved in solid rock are going to last millenia, particularly if they were filled in with dirt afterwards.
The Facts: Mars has a very dry, desert environment. It has little tectonic activity and no rain. What it does have is strong seasonal winds that cause major dust storms that cause major erosion.
The Conjecture: Over 100 million years, even the great pyramids would be eroded away as they were buried and unburied by the winds.
I would guess that only small metals artifacts might survive and they would be buried deep.
Jim
Mars has older mountains that have not weathered away. What is a pyramid but a man-made mountain?
It is very, very small compared to a mountain. The Great Pyramid is only 455.2 ft high. When it was built, it was only 480.9 ft. Over 3000 years the erosion has already been significant. We are now expanding this span to 100 Million years. I will stand by my conjecture for now.
Jim
How good are wind-blown sands at erosion? I recall arguments about whether the san dstone arches in Utah were really abraded by wind (as usually claimed) or by flowing water. I have to admit the case for flowing water seemed better.
There certainly are windblown-sand-abraded rocks (the Museum of Science in Utah has a riock with a hole through it from Antarctica that can be explained as wind erosion much more plausibly than water erosion.), but I suspect it’s a lot less efficient that flowing water. Masrs hasn’t had a lot of the water, so i suspect things can last quite a while on Mars. especially if any stone or building concrete is tougher than sandstone.
The erosion rates on Mars for the last 3.5 billion years have been extremely low, much lower than on Earth. Over that period, measurements by Mars Pathfinder indicate erosion of rocks at a rate of 0.01–0.04 nanometers per year, so the cumulative rate over a period of 100 million years would be less than a tenth of an inch. Yeah, a pyramid would still be there.
I do not know, I am parroting things I have learned in reading about Mars. I will now try to find a cite to the Martian wind erosion effects.
This **PDF ** from Science Mag from 1999, would seem to indicate I am overestimating the effects of Wind Erosion (aeolian erosion).
Example of Wind Erosion: http://www.space.com/imageoftheday/image_of_day_030418.html
It appears that until recently, the facts I presented above was a commonly accepted theory that wind erosion did play a large affect in reshaping Mars. Now it appears this theory is losing support.
I know I’ve commited my share of typos around here, but please-- it’s “Martian”, not Martain or Martyain.
The Martians would be detectable by the absence of certain usable strata in the geology of their planet. Mining for metals disturbs the normal layering of sedimentary rock. Their “atomic age” would have left isotope irregularities in subsequent layers. In later years the frantic efforts to replace atmospheric oxygen from geologic reservoirs would leave mining scars as well.
A city the size of New York will leave unnatural distributions of elements for many millions of years after the city itself is abandoned. Copper, iron, and other civilization specific minerals will have very non natural concentrations for at least several dozen feet, even assuming inundation, and wind erosion for a hundred million years. Even world wide layers of specific elements would eventually be correctly interpreted. (As the iridium layer on Earth will eventually be understood to be the result a super weapon of a war among the intelligent dinosaurs.)
I imagine among the special instruments to be used by survey ships of the Galactic Orthopological Survey (Let’s try to start loosing that humanocentric Anthro thing now, huh?) will be a set designed to examine deposition strata for “anomalies” known to indicate prior periods of civilization. It will be a fairly standard mechanically gathered set of data, eventually provided by probes, and maintained in the Galactic Orthopology Library, and made available to sentients throughout the Interspecies League.
Of course heavy planet geological patterns will only be of interest to those for whom that environment is of economic interest, and the nature of cloud system ecologies might entirely escape the notice of terrestrial types.
Tris
That face held up pretty well.
There is no face.
I think (I hope) it was a joke.
No, actually, there really is no face!
Just shadows, on the rocks.
Yep. Here is a set of comparison photos on NASA’s website showing the “face” at increasing resolution and differing lighting conditions over the years.
Wow, almost totally eroded in just 25 years. That means it must have been carved just a hundred years or so ago!
So talk to the hand, instead.
No, there is no spoon.
About the face, it was a joke. Sorry, next time smilies, I promise.
…see, little green men!
As the atmosphere thinned, the Martains tried to replenish it (by recuing the iron ovixe dust)-this failed, and the oxygen went back to the iron-which is why Mars is coated with red iron oxide dust. Will the archaologists find any tombs/martian remains?
And if there really was evidence of a Martian civilization NASA sure as hell wouldn’t try to hide it. They’d never have to worry about funding again.