by Chris Peterson » Mon May 12, 2014 6:32 pm
superwillbee wrote:Chris Peterson wrote:superwillbee wrote:Maps show that the Valles Marineris has a east-west orientation. And this makes me wonder whether it may have been winds that produced this Valley.
No. It is pretty clear that it is a tectonic structure formed a very long time ago, and subsequently eroded by flowing water, CO
2, and/or soil.
So let's say it is a tectonic structure of mainly pumice-like-materials, formed a very long time ago, and subsequently eroded bij flowing water and/or wind, CO2 and/or soil. Waters moving west and east due to ebb and flood, and winds tending to go east and west too, around the equator of planets.
As sand dunes look very much like beach structures, i doubt if we can be sure and choose between water and winds that would have formed this Valley in billions of years. And i very much doubt we can be 100% sure about it today, millions of years later. And assuming there was water, i'm pretty sure there must have been an atmosphere too, and winds.
Just to say "No. It's pretty clear".. etc. is no fun at all. Dear Chris Peterson, give doubt a chance, don't be a kill-joy!
Give doubt a chance!
I prefer to base my understanding on evidence. And the evidence in this case doesn't leave much room for doubt about the general processes involved here.
You propose, without justification or explanation, a "tectonic structure of mainly pumice-ike-materials". Yet we have no evidence for the existence of such structures, either on the Earth or Mars. The primary output of volcanic regions (like Tharsis) is magma, leading to basaltic rocks. What explanation would you propose for producing thousands of meters of pumice, a material only observed in shallow beds and as isolated stones and pebbles?
Aeolian bedforms and other structures are certainly present on Mars, and are similar to those on Earth. They are readily distinguished from fluvial structures. And neither explains a structure like Valles Marineris, while a tectonic rift zone explains every observed feature, and is consistent with the volcanics and plate structures seen in the region.
The bottom line is that yours is an explanation in search of a question.
[quote="superwillbee"][quote="Chris Peterson"][quote="superwillbee"]Maps show that the Valles Marineris has a east-west orientation. And this makes me wonder whether it may have been winds that produced this Valley.[/quote]
No. It is pretty clear that it is a tectonic structure formed a very long time ago, and subsequently eroded by flowing water, CO[sub]2[/sub], and/or soil.[/quote]
So let's say it is a tectonic structure of mainly pumice-like-materials, formed a very long time ago, and subsequently eroded bij flowing water and/or wind, CO2 and/or soil. Waters moving west and east due to ebb and flood, and winds tending to go east and west too, around the equator of planets.
As sand dunes look very much like beach structures, i doubt if we can be sure and choose between water and winds that would have formed this Valley in billions of years. And i very much doubt we can be 100% sure about it today, millions of years later. And assuming there was water, i'm pretty sure there must have been an atmosphere too, and winds.
Just to say "No. It's pretty clear".. etc. is no fun at all. Dear Chris Peterson, give doubt a chance, don't be a kill-joy!
Give doubt a chance![/quote]
I prefer to base my understanding on evidence. And the evidence in this case doesn't leave much room for doubt about the general processes involved here.
You propose, without justification or explanation, a "tectonic structure of mainly pumice-ike-materials". Yet we have no evidence for the existence of such structures, either on the Earth or Mars. The primary output of volcanic regions (like Tharsis) is magma, leading to basaltic rocks. What explanation would you propose for producing thousands of meters of pumice, a material only observed in shallow beds and as isolated stones and pebbles?
Aeolian bedforms and other structures are certainly present on Mars, and are similar to those on Earth. They are readily distinguished from fluvial structures. And neither explains a structure like Valles Marineris, while a tectonic rift zone explains every observed feature, and is consistent with the volcanics and plate structures seen in the region.
The bottom line is that yours is an explanation in search of a question.