by rockwiler » Mon Feb 26, 2007 5:21 am
Well, sure there is probably life on Mars. It probably got there from Earth from ejecta of meteor strikes. Higher life is pretty doubtful, however. The chemistry was probably never right for that.
This picture and the accompanying text on APOD is really odd. Looking at the detailed version, it is hard to see how any case could be made that the white stuff is related to mineralizing solutions altering the rock. Those subparallel cut-like features clearly cross bedding and are incised into the beds, yet they show little, and in places, no evidence that the white stuff is IN the rock. It looks much more like the white stuff is ON the rocks. To my eye it looks like snow drifts. (Looks like. I'm not saying it is snow.) My guess is that it is some drifted material like snow, that is preferentially accumulated on the texturally rougher surfaces. Maybe it is frost, or dry ice frost, that has blown around.
I can't honestly understand why they still talk about "maybe it was water that did this, and that, and the other." For Pete's sake we've been over that. It is manifest from the evidence that YES, THERE WAS WATER! Let's move on.
Back to this picture. These layers are on edge. There is not much evidence of erosion in this picture, at least not that has left familar erosional features like dendritic drainages. I am wondering where the rest of the material went. Where did the rest of the layers go...the part that originally extended above the current surface but now is gone leaving only what is visible. Some resurfacing process has been at work also - the absence of craters suggests a relatively young surface. Is/Was there a tectonic process that put these layers on edge when they were probably deposited nearly horizontal to begin with?
Here is another thought. Soft sediment deformation on this scale, and a stratigraphic thickness on the order of a couple kilometers suggests a fairly deep and fairly dynamic depositional setting. This almost certainly means water and plenty of it, and also either a) a high deposition rate resulting in oversteepening of the sediment pile, or b) a dynamic, tectonically active depositional basin that resulted in tectonic oversteepening of an unlithified sediment pile.
Movement of massive amounts of sediment also requires movement of surface waters, either via rain, or some major springs system. I'd guess rain. Rain may have been a short lived process however. Just because there was lots of water doesn't mean it stayed around for long. Perhaps the Olympus Mons eruptions served to devolatilize the interior of Mars, pumping lots of water into the atmosphere for some short period (1-100 million years) resulting briefly in an atmosphere capable of producing rain. In the process water was expelled from deep in the planet to the near-surface environment.
Food for thought. javascriptemoticon('8)')
Well, sure there is probably life on Mars. It probably got there from Earth from ejecta of meteor strikes. Higher life is pretty doubtful, however. The chemistry was probably never right for that.
This picture and the accompanying text on APOD is really odd. Looking at the detailed version, it is hard to see how any case could be made that the white stuff is related to mineralizing solutions altering the rock. Those subparallel cut-like features clearly cross bedding and are incised into the beds, yet they show little, and in places, no evidence that the white stuff is IN the rock. It looks much more like the white stuff is ON the rocks. To my eye it looks like snow drifts. (Looks like. I'm not saying it is snow.) My guess is that it is some drifted material like snow, that is preferentially accumulated on the texturally rougher surfaces. Maybe it is frost, or dry ice frost, that has blown around.
I can't honestly understand why they still talk about "maybe it was water that did this, and that, and the other." For Pete's sake we've been over that. It is manifest from the evidence that YES, THERE WAS WATER! Let's move on.
Back to this picture. These layers are on edge. There is not much evidence of erosion in this picture, at least not that has left familar erosional features like dendritic drainages. I am wondering where the rest of the material went. Where did the rest of the layers go...the part that originally extended above the current surface but now is gone leaving only what is visible. Some resurfacing process has been at work also - the absence of craters suggests a relatively young surface. Is/Was there a tectonic process that put these layers on edge when they were probably deposited nearly horizontal to begin with?
Here is another thought. Soft sediment deformation on this scale, and a stratigraphic thickness on the order of a couple kilometers suggests a fairly deep and fairly dynamic depositional setting. This almost certainly means water and plenty of it, and also either a) a high deposition rate resulting in oversteepening of the sediment pile, or b) a dynamic, tectonically active depositional basin that resulted in tectonic oversteepening of an unlithified sediment pile.
Movement of massive amounts of sediment also requires movement of surface waters, either via rain, or some major springs system. I'd guess rain. Rain may have been a short lived process however. Just because there was lots of water doesn't mean it stayed around for long. Perhaps the Olympus Mons eruptions served to devolatilize the interior of Mars, pumping lots of water into the atmosphere for some short period (1-100 million years) resulting briefly in an atmosphere capable of producing rain. In the process water was expelled from deep in the planet to the near-surface environment.
Food for thought. javascriptemoticon('8)')